EP2619461B1 - Device and method for reliably operating a compressor at the pump threshold - Google Patents

Device and method for reliably operating a compressor at the pump threshold Download PDF

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Publication number
EP2619461B1
EP2619461B1 EP11813656.3A EP11813656A EP2619461B1 EP 2619461 B1 EP2619461 B1 EP 2619461B1 EP 11813656 A EP11813656 A EP 11813656A EP 2619461 B1 EP2619461 B1 EP 2619461B1
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EP
European Patent Office
Prior art keywords
compressor
blade
impeller
state
blades
Prior art date
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EP11813656.3A
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German (de)
French (fr)
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EP2619461A1 (en
Inventor
Malte Köller
Olaf Magnor
Daniel Reitebuch
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IAV GmbH Ingenieurgesellschaft Auto und Verkehr
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IAV GmbH Ingenieurgesellschaft Auto und Verkehr
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/001—Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/02—Surge control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2270/00—Control
    • F05D2270/01—Purpose of the control system
    • F05D2270/10—Purpose of the control system to cope with, or avoid, compressor flow instabilities
    • F05D2270/101—Compressor surge or stall
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2270/00—Control
    • F05D2270/70—Type of control algorithm
    • F05D2270/708—Type of control algorithm with comparison tables

Definitions

  • the present invention relates to a device according to the preamble of claim 6 and a method according to the preamble of claim 1 for safe operation of a compressor at the surge line.
  • a device and such a method is for example from the US-A-4,955,269 bekant.
  • Compressors are thermal turbomachines and are used for compressing gases, in particular air. Compressors find in engine construction for continuously or periodically operating internal combustion engines far-reaching application and are used for example in reciprocating engines to increase performance, in gas turbines for generating electrical energy or in jet engines for propulsion of aircraft to compress the necessary air for combustion. The drive of the compressor takes place for example by the utilization of the energy contained in the exhaust gas, but can also be done mechanically or electrically.
  • the compressor can be designed according to its application, for example, in a jet engine as axial compressor to achieve high mass flows.
  • a mass flow is to be understood as an air mass which is conveyed through the compressor for a specific time.
  • variables related to geometric conditions or environmental conditions such as throughput or volumetric flow, may be used to characterize the operation of the compressor.
  • the air to be compressed flows axially to the compressor from the environment and is transported by the compressor in the jet engine and thereby compressed.
  • the compressor is generally constructed of a mounted on a shaft impeller with compressor blades, which rotates in a housing with corresponding guide vanes and thus forms a compressor stage.
  • the provided with a blade root compressor blades are mounted playfully on the impeller so that the compressor blade center itself at a sufficiently fast rotation of the impeller due to the resulting outward centrifugal force and sit firmly in the impeller.
  • the blades are firmly connected to the impeller.
  • the Guide vanes are fixed to the housing.
  • several compressor stages can be arranged one behind the other in the compressor for jet engines, so as to form a multi-stage compressor.
  • the compressor can be preceded by a blower and a second compressor.
  • the drive of the impeller is via the shaft, which is driven by a turbine at the end of the jet engine.
  • the compressor capacity is set by the impeller speed and by the mass flow in the compressor.
  • the drive power of the shaft can be changed by the turbine to adjust the speed of the impeller.
  • the mass flow in the compressor can be varied by means of adjustable guide vanes, blow-off valves or blade tip gap change. This makes it possible to set an operating point of the compressor, which defines itself for example by a pressure ratio and a mass flow, by compressor power and speed or other alternatives.
  • the pressure ratio of a compressor stage is limited by the fact that the compressed air in the compressor stage can not follow the compressor blade contour arbitrarily, but separates starting from the trailing edge of the compressor blade.
  • the maximum step pressure ratio increases with increasing mass flow and represents the outermost limit of the stable operating range as a pumping limit.
  • the maximum mass flow of the compressor stage is limited by a plug limit as soon as a flow velocity at the level of the sound velocity develops in a flow cross section, usually at the compressor inlet limited mass flow.
  • a pressure difference is established between the upper and lower sides. Since a compressor blade is an elastic component, it will yield to the pressure difference between top and bottom and bend. With increasing load, the deflection and thus the deflection of the compressor blades increase.
  • the operating range of the compressor is thus limited on the one hand by the surge limit and on the other hand by the stuffing limit.
  • the pumping limit is an unfavorable for the compressor, unstable operating condition in which it destroys the Compressor can come. This unstable operating condition must be avoided, especially when using the compressor in jet engines, in order to ensure operational safety.
  • the course of the surge limit of the operating range is subject to operational and aging-related changes.
  • the pump size is influenced by the changes in ambient conditions during flight operation, compressor inlet conditions, the thermal inertia of the components and the intrusion of foreign objects. Changes in the top clearance of the compressor blades towards the housing, changes in the bearing clearance due to aging and wear, deformations and deposits of the blade geometries and on the housing have an influence on the surge limit.
  • the surge margin for new engines is designed to be about 25% of the pressure ratio, so that it has been reduced to 5% by the age-related lowering of the surge limit by the end of the life of the compressor.
  • the efficiency optimum of a compressor is generally close to the surge limit in the stable operating range, resulting in a consumption disadvantage due to the safety-relevant design of the surge margin. Therefore, from the prior art devices and methods for operating compressors are known, with which the compressors are to be protected against this dangerous operating condition with optimal Verêtr Obersrad. For example, bleed valves are used to lower the pressure ratio across a compressor stage. In many cases, an adjustment rotatably mounted vanes is provided with which the pressure ratio or the mass flow can be varied, thus ensuring a safe, stable operating condition. Furthermore, an active change of the top clearance of the compressor blade by heating or cooling of the compressor housing is known. As a prerequisite, however, a reliable detection of the operating state of the compressor and accordingly the distance of the current operating point of the compressor to the surge limit is necessary.
  • the compressor blade tip deflection may be calculated from the time difference of the measured compressor blade tip transit time at a sensor on the housing and an ideal transit time that would result from an ideally rigid compressor blade and the known tangential velocity of the compressor blade tip.
  • the transit time is understood as the point in time at which the compressor blade tip is located at least partially in the sensor region of the sensor on the housing of the compressor. In this case, for example, the entry into the sensor area, the passage through the sensor area or the exit from the sensor area can be defined in order to define the transit time.
  • the method is therefore based on the identification of signs of an unstable compressor state. It is known that these precursors show up a few milliseconds before the onset of compressor instability, so that there is no longer sufficient time to carry out countermeasures, for example reducing the fuel mass, opening the blow-off valves or adjusting the guide vanes.
  • the publication DE 10 2008 036 305 A1 describes a method in which a power consumption of the compressor is determined from the transit times of the individual compressor blades. For this, the real transit times are compared with the ideal model transit times and their difference evaluated as a result of the deflection of the compressor blades. From the deflection of the compressor blades can be calculated a compressor torque and, accordingly, with the compressor speed, a compressor power. In stable operating conditions, a balance between the drive power and the compressor power sets. A disturbance of this power balance is considered to be incipient instability and the approach to the surge line is indicated.
  • the condition such as wear, fouling, erosion and deformation on the compressor blades, as well as the change in the position of the compressor blades, which reorient themselves at each engine start by the Schaufelfußspiel, have an influence on the measured passage time in relation to the nominal passage time, based on the deflection or the deflection of the compressor blades is determined and closed at the operating point and its distance from the surge line.
  • the methods known in the prior art can not detect and eliminate this influence, so that it can lead to false detection. A reliable determination of the operating point of the compressor and thus the surge margin of the operating point is not possible.
  • the object of the invention is to provide a method and a device with which a reliable detection of the operating state of the compressor is made possible.
  • the detection should be independent of influences from a changed state or a changed position of the compressor blades.
  • the state of each individual compressor blade defines a deviation from an ideal state and has an influence on the real measured transit time.
  • the transit time is understood as the point in time at which the compressor blade tip is located at least partially in a sensor region of a sensor on the housing of the compressor.
  • the entry into the sensor area, the passage through the sensor area or the exit from the sensor area can be used to define the transit time.
  • each compressor blade on the impeller may change each time it is started. Since the compressor blades are mounted playfully in the impeller and only at startup of the compressor at a minimum speed due to centrifugal self-align and anchor in the leadership, these deviations come from operational use to operational use to conditions. Even with compressors with fixedly attached to the impeller compressor blades, a change in position, for example by assembly work done.
  • the ideal transit time is understood to mean the point in time which would result for an ideal impeller with equidistant compressor blade arrangement and infinitely stiff compressor blades without deviations from state and position.
  • the transit time is understood as the point in time at which the compressor blade tip is located at least partially in the sensor region of the sensor on the housing of the compressor.
  • the entry into the sensor area, the passage through the sensor area or the exit from the sensor area can be defined in order to define the transit time.
  • the compressor blades align.
  • the deviations of the compressor blade from the ideal state in terms of condition and position remain constant for this operation and can be compensated. Only loosen when lowering the compressor below a certain minimum speed the compressor blades are corresponding to the foot play and the deviations are again undetermined ..
  • the invention provides a method with which a reliable detection of the operating state is made possible regardless of the state and position of the compressor blades and thereby an optimal compressor operation.
  • the deviations from the ideal state of each individual compressor blade during startup of the compressor after reaching the minimum speed for aligning the compressor blades are determined. Based on this compressor blade individually determined deviation can be carried out a correction of the measured during operation passage times of each compressor blade. This correction allows an accurate determination of the operating state and a Wirkwirkgsgradoptimal operation of the compressor below the surge limit.
  • the deviations of the compressor blades are compared with the ideal state redetermined, adapted and included in the evaluation.
  • the thus measured measured passage times are used to determine the deflection due to the deflection of the compressor blade, according to the invention advantageously only the deflection is determined as a result of the fluid mechanics. An independent of the condition and the position of the compressor blades operating point determination is achieved.
  • the invention further provides a device with which the deviations are determined and a correction of the passage times takes place.
  • the apparatus includes at least one sensor for indicating the passage of a compressor blade, henceforth called a compressor blade sensor, and at least one sensor for indicating the rotation of the rotor, henceforth called impeller sensor.
  • the compressor blade sensor outputs a trigger signal as a compressor blade passes.
  • a marking or the like may be provided on the compressor blade tip. From the signal, the transit time is determined.
  • the impeller sensor outputs a trigger signal corresponding to the rotation of the impeller. From this, for example, the speed of the impeller can be calculated. Again, appropriate markings may be provided.
  • the trigger signals of the sensors are related to each other by means of a central time base, so that an accurate assignment of the trigger signals of the impeller and compressor blades can take place. Accordingly, the comparison of the compressor blade sensor and the impeller sensor can be used to compare the measured and ideal transit time for each individual compressor blade.
  • a compressor nominal model is used in accordance with the invention, which images the impeller with the compressor blades as an ideal impeller with equidistant compressor blade arrangement with infinitely rigid ideal compressor blades without deviations from condition and position.
  • the compressor nominal model may be modeled as a memory array in which memory cells equal to the number of compressor blades are present. Each individual compressor blade is assigned an individual memory cell.
  • the compressor nominal model of the measured rotational speed of the impeller is adjusted in phase, so that a direct comparison between the real impeller and the ideal impeller, represented by the compressor nominal model, is possible. As a result, a memory cell rotation equal to the rotation of the real impeller is achieved.
  • a synchronized with the rotation of the impeller counter can be used, with which the individual memory cell of the memory array can be addressed.
  • the compressor nominal model now provides for each individual compressor blade passing through the compressor blade sensor the individual ideal transit time, that is, the time that a geometrically ideal and infinitely rigid compressor blade would produce at the sensor.
  • the difference between the ideal transit time and the actual transit time of the respective compressor blade measured at the compressor gives the deviation, ie the relative transit time.
  • a differentiator is provided in the device according to the invention in order to carry out the corresponding operation.
  • the relative transit time is equal to zero for the ideal case and, in the real case, is composed of a state-related and position-dependent deviation and the actual useful signal, ie the flow-related deviation.
  • the flow-mechanical component of the deviation can be regarded as negligible, so that the state and conditional deviation prevails.
  • This condition-related and position-dependent deviation is assigned to a compressor adaptation model in a compressor-specific manner, with the compressor adaptation model corresponding to the compressor nominal model correspondingly having the same number of memory cells.
  • the compressor adaptation model is integrated with a switching unit with which switching is made between working mode and learning or adaptation mode. If the adaptation mode is enabled, for example by speed thresholds of the impeller, the adaptation can take place.
  • the compressor blade individual state and positional deviations from the compressor adaptation model are used to correct the relative transit time of the respective compressor blade to a corrected relative transit time, such that only the flow-mechanical fraction calculates the deflection the compressor blade is calculated.
  • the state and location-related deviations stored in the compressor adaptation model can be stored as a distance or as a factor in the form of a time, a path or an angle and so on.
  • the measured transit time or the relative transit time calculated therefrom can be used.
  • the impeller speed or tangential velocity of the compressor blade tips is used to calculate an absolute deviation as the path or angle from the ideal condition.
  • geometric parameters of the compressor and its components can be included in the evaluation.
  • the compressor nominal model can be combined with the compressor adaptation model.
  • a sensor configuration can be used, which consists of at least two compressor blade sensors and an impeller sensor. If only one sensor is present, blade oscillations with the same or multiple frequency of the impeller frequency can not be detected. By increasing the number of compressor blade sensors and their irregular distribution over the compressor circumference also these frequencies can be detected. Sensors with different functions can be used. However, a combination of transmission sensitivity and distance sensitivity would have the advantage of allowing gap control for the compressor blades.
  • the calculation of the angle of attack from the available information offers.
  • the calculated angle of incidence is continuously entered into a writable map and thus determined and recorded during the operating time of the engine whose operating map. It is also known from experiments on the test bench, at which angle of attack it comes to the flow separation and thus to the compressor pumping, so that the surge limit is firmly stored in the map. Non-volatile memory behavior keeps this information even after the engine has been shut down, so that there is a fixed safety threshold for the stable operation of the jet engine.
  • the method according to the invention can be applied to a compressor stage or to several or selected compressor stages, which are particularly affected by the risk of pumping.
  • the method of the present invention is capable of not only detecting compressor instabilities by compressor blade viewing, but also distinguishing between rotating separations and compressor blade flutter as rotating separations circulate unlike compressor blade flutter.
  • the inventive method allows an optimal adjustment of the actuators of a compressor, since the actual operating state of the compressor and the position of the surge limit are known.
  • the compressor can thus be operated with optimum efficiency, without having to be driven into the unstable operating state. As a result, the specific consumption is lowered.
  • the compressor can be designed, for example, lighter and smaller.
  • the method according to the invention does not require the approach to the surge line in order to be able to determine its position. As a result, safety is increased.
  • the method according to the invention continuously adapts the operating map, so that the operation of the compressor is continuously adapted to its aging state. As a result, the specific consumption decreases. If, for example, a compressor instability occurs, which can be detected by the method, this behavior is corrected in the operating map by adjusting the surge limit.
  • the method according to the invention predicts the failure behavior of the compressor so that unplanned maintenance is avoided and the available service life is known. As a result, operating costs, maintenance costs, conventional costs and storage costs are reduced and availability is increased.
  • the method according to the invention is also compatible with methods of active gap control, in which the gap between the compressor blade tips and the housing is controlled or regulated. Furthermore, the use of variable vanes and the bleed air take-off can be optimized.
  • the exemplary configured device consists of a compressor blade sensor (1) which outputs a trigger signal corresponding to the passage of a compressor blade and an impeller sensor (2) which outputs a trigger signal corresponding to one revolution of the impeller of the compressor.
  • the two trigger signals are provided with a time stamp.
  • the device is equipped with a compressor nominal model (4) and a compressor adaptation model (5) which run through in phase by means of a controller (6) to the speed of the impeller.
  • the controller (6) performs an intervention according to the control deviation.
  • the compressor nominal model (4) as well as the compressor adaptation model (5) consists of a plurality of memory cells (4a, 5a), the number of memory cells of each model corresponding to the number of compressor blades.
  • the memory cells are addressed in phase according to the speed of the impeller by the controller (6) .
  • the compressor nominal model (4) outputs an ideal transit time corresponding to the current compressor blade, which is compared in a differentiator (7) with the measured transit time and outputs a relative transit time. Thereafter, adapted in a Lemmodus state and position deviations of the respective compressor blade from the compressor adaptation model (5) are offset with the relative transit time. So that the compressor adaptation model (5) can be adapted, a switch (8) is provided, which switches over into an adaptation mode when a condition (9) is met . If condition (9) is not fulfilled, the device is operated in working mode. The device outputs at least operating point information calculated from the corrected relative transit time and other quantities in an evaluation unit (10) .
  • the compressor nominal model (4) may be replaced by a function which outputs the ideal transit time in dependence on the impeller speed, since this is the same for all compressor blades and the model impeller of the ideal impeller.
  • the compressor adaptation model ( 5) can be replaced by a characteristic map whose characteristic diagram points can be addressed discretely and output the deviation of the respective compressor blade.
  • the map points can be done for example by means of a synchronized with the impeller counter.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Air Blowers (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Description

Technisches GebietTechnical area

Die vorliegende Erfindung betrifft eine Vorrichtung gemäß dem Oberbegriff des Anspruchs 6 und ein Verfahren gemäß dem Oberbegriff des Anspruchs 1 zum sicheren Betreiben eines Verdichters an der Pumpgrenze. Eine solche Vorrichtung und ein solches Verfahren ist z.B. aus der US-A-4 955 269 bekant.The present invention relates to a device according to the preamble of claim 6 and a method according to the preamble of claim 1 for safe operation of a compressor at the surge line. Such a device and such a method is for example from the US-A-4,955,269 bekant.

Stand der TechnikState of the art

Verdichter sind thermische Strömungsmaschinen und werden zum Verdichten von Gasen, insbesondere Luft verwendet. Verdichter finden im Motorenbau für kontinuierlich oder periodisch arbeitende Brennkraftmaschinen weitreichende Anwendung und werden beispielsweise in Hubkolbenmotoren zur Leistungssteigerung, in Gasturbinen zur Erzeugung elektrischer Energie oder auch in Strahltriebwerken zum Antrieb von Flugzeugen eingesetzt, um die für die Verbrennung notwendige Luft zu verdichten. Der Antrieb des Verdichters erfolgt beispielsweise durch die Ausnutzung der im Abgas enthaltenen Energie, kann aber auch mechanisch oder elektrisch erfolgen.Compressors are thermal turbomachines and are used for compressing gases, in particular air. Compressors find in engine construction for continuously or periodically operating internal combustion engines far-reaching application and are used for example in reciprocating engines to increase performance, in gas turbines for generating electrical energy or in jet engines for propulsion of aircraft to compress the necessary air for combustion. The drive of the compressor takes place for example by the utilization of the energy contained in the exhaust gas, but can also be done mechanically or electrically.

Der Verdichter kann nach seinem Einsatzgebiet beispielsweise in einem Strahltriebwerk als Axialverdichter ausgeführt sein, um hohe Masseströme zu erreichen. Als Massestrom ist eine Luftmasse zu verstehen, welche während einer bestimmten Zeit durch den Verdichter gefördert wird. Alternativ können auch auf geometrische Bedingungen oder auf Umgebungsbedingungen bezogene Größen, wie Durchsatz oder Volumenstrom verwendet werden, um den Betrieb des Verdichters zu charakterisieren. Die zu verdichtende Luft strömt den Verdichter aus der Umgebung axial an und wird durch den Verdichter im Strahltriebwerk befördert und dabei verdichtet. Dazu ist der Verdichter im Allgemeinen aus einem auf einer Welle gelagerten Laufrad mit Verdichterschaufeln aufgebaut, welches sich in einem Gehäuse mit entsprechenden Leitschaufeln dreht und somit eine Verdichterstufe bildet. Die mit je einem Schaufelfuß versehenen Verdichterschaufeln sind am Laufrad spielend eingehangen, so dass sich die Verdichterschaufet bei einer ausreichend schnellen Drehung des Laufrades auf Grund der entstehenden nach außen gerichteten Fliehkraft selbst zentrieren und fest im Laufrad sitzen. Alternativ sind die Schaufeln fest mit dem Laufrad verbunden. Die Leitschaufeln sind fest am Gehäuse angeordnet. Zur Erhöhung der Verdichtung können in dem Verdichter für Strahltriebwerke mehrere Verdichterstufen hintereinander angeordnet sein, um so einen mehrstufigen Verdichter zu bilden. Weiterhin kann dem Verdichter ein Gebläse sowie ein zweiter Verdichter vorgeschaltet sein. Der Antrieb des Laufrades erfolgt über die Welle, welche durch eine Turbine am Ende des Strahltriebwerks angetrieben wird.The compressor can be designed according to its application, for example, in a jet engine as axial compressor to achieve high mass flows. A mass flow is to be understood as an air mass which is conveyed through the compressor for a specific time. Alternatively, variables related to geometric conditions or environmental conditions, such as throughput or volumetric flow, may be used to characterize the operation of the compressor. The air to be compressed flows axially to the compressor from the environment and is transported by the compressor in the jet engine and thereby compressed. For this purpose, the compressor is generally constructed of a mounted on a shaft impeller with compressor blades, which rotates in a housing with corresponding guide vanes and thus forms a compressor stage. The provided with a blade root compressor blades are mounted playfully on the impeller so that the compressor blade center itself at a sufficiently fast rotation of the impeller due to the resulting outward centrifugal force and sit firmly in the impeller. Alternatively, the blades are firmly connected to the impeller. The Guide vanes are fixed to the housing. To increase the compression, several compressor stages can be arranged one behind the other in the compressor for jet engines, so as to form a multi-stage compressor. Furthermore, the compressor can be preceded by a blower and a second compressor. The drive of the impeller is via the shaft, which is driven by a turbine at the end of the jet engine.

Beim Betrieb des Verdichters wird die Verdichterleistung durch die Laufraddrehzahl und durch den Massestrom im Verdichter eingestellt. Dafür kann beispielsweise die Antriebsleistung der Welle durch die Turbine verändert werden, um die Drehzahl des Laufrades einzustellen. Der Massestrom im Verdichter kann über verstellbare Leitschaufeln, Abblasventile oder Schaufelspitzenspaltänderung variiert werden. Dadurch lässt sich ein Betriebspunkt des Verdichters einstellen, welcher sich beispielsweise durch ein Druckverhältnis und einen Massestrom, durch Verdichterleistung und Drehzahl oder andere Alternativen definiert.When operating the compressor, the compressor capacity is set by the impeller speed and by the mass flow in the compressor. For example, the drive power of the shaft can be changed by the turbine to adjust the speed of the impeller. The mass flow in the compressor can be varied by means of adjustable guide vanes, blow-off valves or blade tip gap change. This makes it possible to set an operating point of the compressor, which defines itself for example by a pressure ratio and a mass flow, by compressor power and speed or other alternatives.

Das Druckverhältnis einer Verdichterstufe wird dadurch nach oben begrenzt, dass die in der Verdichterstufe verdichtete Luft nicht beliebig der Verdichterschaufelkontur folgen kann, sondern sich beginnend von der Hinterkante der Verdichterschaufel ablöst. Das maximale Stufendruckverhältnis steigt mit zunehmendem Massestrom an und stellt die äußerste Grenze des stabilen Betriebsbereiches als Pumpgrenze dar. Der maximale Massestrom der Verdichterstufe wird durch eine Stopfgrenze begrenzt, sobald sich in einem Strömungsquerschnitt, üblicherweise am Verdichtereintritt eine Strömungsgeschwindigkeit in Höhe der Schallgeschwindigkeit ausbildet und dadurch den durchgesetzten Massestrom begrenzt.The pressure ratio of a compressor stage is limited by the fact that the compressed air in the compressor stage can not follow the compressor blade contour arbitrarily, but separates starting from the trailing edge of the compressor blade. The maximum step pressure ratio increases with increasing mass flow and represents the outermost limit of the stable operating range as a pumping limit. The maximum mass flow of the compressor stage is limited by a plug limit as soon as a flow velocity at the level of the sound velocity develops in a flow cross section, usually at the compressor inlet limited mass flow.

In Abhängigkeit vom Anströmwinkel oder der Anströmgeschwindigkeit der Luft an die Verdichterschaufel stellt man zwischen Ober- und Unterseite einen Druckunterschied fest. Da es sich bei einer Verdichterschaufel um ein elastisches Bauteil handelt, wird sie dem Druckunterschied zwischen Ober- und Unterseite nachgeben und sich durchbiegen. Mit zunehmender Belastung steigen die Durchbiegung und damit die Auslenkung der Verdichterschaufeln.Depending on the angle of attack or the flow velocity of the air to the compressor blade, a pressure difference is established between the upper and lower sides. Since a compressor blade is an elastic component, it will yield to the pressure difference between top and bottom and bend. With increasing load, the deflection and thus the deflection of the compressor blades increase.

Der Betriebsbereich des Verdichters wird somit einerseits durch die Pumpgrenze und andererseits durch die Stopfgrenze begrenzt. Dabei ist die Pumpgrenze ein für den Verdichter ungünstiger, instabiler Betriebszustand, bei dem es zur Zerstörung des Verdichters kommen kann. Dieser instabile Betriebszustand ist vor allem beim Einsatz des Verdichters in Strahltriebwerken unbedingt zu vermeiden, um die Betriebssicherheit zu gewährleisten.The operating range of the compressor is thus limited on the one hand by the surge limit and on the other hand by the stuffing limit. The pumping limit is an unfavorable for the compressor, unstable operating condition in which it destroys the Compressor can come. This unstable operating condition must be avoided, especially when using the compressor in jet engines, in order to ensure operational safety.

Pumpen tritt auf, wenn der für ein Druckverhältnis über eine Verdichterstufe erforderliche Massestrom zu gering ist, beziehungsweise das Druckverhältnis für einen bestimmten Massestrom zu groß ist und es dadurch zu einer Rückströmung und somit zu einem Strömungsabriss kommt. Dadurch werden das Druckverhältnis und der Massestrom kurzzeitig verändert, wodurch sich der Betriebspunkt kurzzeitig im stabilen Bereich befindet und sich danach wiederum der instabile Betriebspunkt einstellt. Dieser zyklisch Wechsel zwischen stabilem und instabilem Betriebszustand nahe der Pumpgrenze kann beispielsweise nur an einigen Verdichterschaufeln eintreten, wobei nur einzelne Verdichterschaufeln einen Strömungsabriss aufweisen und sich dieser Effekt entgegen der Drehrichtung des Verdichterrades fortsetzt. Durch den zyklischen Wechsel der Strömung kommt es zu zyklisch wechselnden Belastungen einzelner Verdichterschaufeln. Durch den zunehmenden Strömungsabriss und die damit verbundene Wechselbelastung beginnt die Verdichterschaufel zu schwingern, wobei sich die Verdichterschaufeln durch diese Wechselbelastung durchbiegen und brechen können. Stellt sich jedoch ein instabiler Betriebszustand über der Pumpgrenze ein, kommt es jedoch zu einem kompletten Strömungsabriss und erheblichen Druckstößen im Verdichter. Im Gesamttriebwerk stellt dieser Zustand eine erhebliche Gefahr durch verlöschende Flammen, brennenden Kraftstoff im Verdichter, Überhitzungen, Deformierungen und so weiter dar, wobei der Verdichter und somit das Strahltriebwerk komplett zerstört werden können.Pumping occurs when the required for a pressure ratio across a compressor stage mass flow is too low, or the pressure ratio for a given mass flow is too large and it comes to a backflow and thus to a stall. As a result, the pressure ratio and the mass flow are changed briefly, whereby the operating point is briefly in the stable range and then adjusts the unstable operating point. This cyclic change between stable and unstable operating state near the surge line, for example, occur only on some compressor blades, with only individual compressor blades have a stall and this effect continues counter to the direction of rotation of the compressor wheel. Due to the cyclical change of the flow cyclically changing loads of individual compressor blades occur. Due to the increasing stall and the associated alternating load, the compressor blade begins to oscillate, whereby the compressor blades can bend and break due to this alternating load. However, if an unstable operating condition above the surge limit occurs, however, a complete stall occurs and considerable pressure surges in the compressor. In the overall engine, this condition represents a significant hazard from extinguishing flames, burning fuel in the compressor, overheating, deformations and so on, whereby the compressor and thus the jet engine can be completely destroyed.

Der Verlauf der Pumpgrenze des Betriebsbereiches unterliegt betriebsbedingten und alterungsbedingten Änderungen. So wird die Pumpgrerize durch die Veränderungen der Umgebungsbedingungen während des Flugbetriebs, Anströmbedingungen des Verdichters, durch die thermische Trägheit der Komponenten sowie durch das Eindringen von Fremdobjekten beeinflusst. Auch Veränderungen im Spitzenspalt der Verdichterschaufeln zum Gehäuse hin, Veränderungen im Lagerspiel durch Alterung und Abnutzung, Verformungen und Ablagerungen der Schaufelgeometrien und am Gehäuse haben Einfluss auf die Pumpgrenze.The course of the surge limit of the operating range is subject to operational and aging-related changes. Thus, the pump size is influenced by the changes in ambient conditions during flight operation, compressor inlet conditions, the thermal inertia of the components and the intrusion of foreign objects. Changes in the top clearance of the compressor blades towards the housing, changes in the bearing clearance due to aging and wear, deformations and deposits of the blade geometries and on the housing have an influence on the surge limit.

Durch einen ausreichend großen Druckverhältnisabstand der zulässigen Betriebszustände des Verdichters zur Pumpgrenze soll die durch die Einflüsse resultierende Absenkung der Pumpgrenze zu niedrigeren Druckverhältnissen berücksichtigt werden. Der kritischste Betriebszustand wird bei der Beschleunigung des Verdichters erreicht, bei dem der Pumpgrenzenabstand vorübergehend verringert wird. In der Praxis wird der Pumpgrenzenabstand für Neutriebwerke auf etwa 25% des Druckverhältnisses ausgelegt, so dass er sich bis zum Ende der Lebensdauer des Verdichters durch die alterungsbedingte Absenkung der Pumpgrenze auf 5% verringert hat.By a sufficiently large pressure ratio distance of the permissible operating states of the compressor to the surge limit, the reduction of the surge limit resulting from the influences to lower pressure ratios should be taken into account. The most critical operating condition is achieved in the acceleration of the compressor, in which the surge margin is temporarily reduced. In practice, the surge margin for new engines is designed to be about 25% of the pressure ratio, so that it has been reduced to 5% by the age-related lowering of the surge limit by the end of the life of the compressor.

Das Wirkungsgradoptimum eines Verdichters liegt im Allgemeinen nahe der Pumpgrenze im stabilen Betriebsbereich, wodurch ein Verbrauchsnachteil auf Grund der sicherheitsrelevanten Auslegung des Pumpgrenzeriabstands entsteht. Deshalb sind aus dem Stand der Technik Vorrichtungen und Verfahren zum Betreiben von Verdichtern bekannt, mit denen die Verdichter vor diesem gefährlichen Betriebszustand bei optimalem Verdichterwirkungsrad geschützt werden sollen. Beispielsweise werden Abblasventile verwendet, um das Druckverhältnis über eine Verdichterstufe zu senken. In vielen Fällen ist eine Verstellung drehbar gelagerter Leitschaufeln vorgesehen, mit denen das Druckverhältnis beziehungsweise der Massestrom variiert werden kann, um somit einen sicheren, stabilen Betriebszustand zu gewährleisten. Weiterhin ist eine aktive Änderung des Spitzenspalts der Verdichterschaufel durch Erwärmung oder Abkühlung des Verdichtergehäuses bekannt. Als Voraussetzung dafür ist jedoch eine sichere Erkennung des Betriebszustandes des Verdichters und dementsprechend der Abstand des aktuellen Betriebspunktes des Verdichters zur Pumpgrenze notwenig.The efficiency optimum of a compressor is generally close to the surge limit in the stable operating range, resulting in a consumption disadvantage due to the safety-relevant design of the surge margin. Therefore, from the prior art devices and methods for operating compressors are known, with which the compressors are to be protected against this dangerous operating condition with optimal Verdichterwirkungsrad. For example, bleed valves are used to lower the pressure ratio across a compressor stage. In many cases, an adjustment rotatably mounted vanes is provided with which the pressure ratio or the mass flow can be varied, thus ensuring a safe, stable operating condition. Furthermore, an active change of the top clearance of the compressor blade by heating or cooling of the compressor housing is known. As a prerequisite, however, a reliable detection of the operating state of the compressor and accordingly the distance of the current operating point of the compressor to the surge limit is necessary.

Die Auslenkung der Verdichterschaufelspitze kann aus der Zeitdifferenz des gemessenen Durchgangszeitpunktes der Verdichterschaufelspitze an einem Sensor am Gehäuse und einem idealen Durchgangszeitpunkt, der sich bei einer ideal steifen Verdichterschaufel ergeben würde, und der bekannten Tangentialgeschwindigkeit der Verdichterschaufelspitze berechnet werden. Als Durchgangszeitpunkt wird der Zeitpunkt verstanden, zu dem sich die Verdichterschaufelspitze wenigstens teilweise im Sensorbereich des Sensors am Gehäuse des Verdichters befindet. Dabei kann beispielsweise der Eintritt in den Sensorbereich, der Durchgang durch den Sensorbereich oder der Austritt aus dem Sensorbereich definiert werden, um den Durchgangszeitpunkt zu definieren.The compressor blade tip deflection may be calculated from the time difference of the measured compressor blade tip transit time at a sensor on the housing and an ideal transit time that would result from an ideally rigid compressor blade and the known tangential velocity of the compressor blade tip. The transit time is understood as the point in time at which the compressor blade tip is located at least partially in the sensor region of the sensor on the housing of the compressor. In this case, for example, the entry into the sensor area, the passage through the sensor area or the exit from the sensor area can be defined in order to define the transit time.

Die Patentschrift US 6,474,935 B1 beschreibt die Erkennung rotierender Ablösungen basierend auf der Messung der Auslenkung der Verdichterschaufelspitzen infolge von Druckschwankungen, die durch die umlaufende Ablösezelle entstehen.The patent US 6,474,935 B1 describes the detection of rotating separations based on the measurement of the displacement of the compressor blade tips due to pressure fluctuations caused by the circulating separation cell.

Das Verfahren beruht demnach auf der Identifikation von Voranzeichen eines instabilen Verdichterzustandes. Bekannt ist, dass sich diese Voranzeichen wenige Millisekunden vor Einsetzen der Verdichterinstabilität zeigen, so dass zur Durchführung von Gegenmaßnahmen, zum Beispiel Verringerung der Brennstoffmasse, Öffnen der Abblasventile oder Verstellen der Leitschaufeln, nicht mehr ausreichend Zeit verbleibt.The method is therefore based on the identification of signs of an unstable compressor state. It is known that these precursors show up a few milliseconds before the onset of compressor instability, so that there is no longer sufficient time to carry out countermeasures, for example reducing the fuel mass, opening the blow-off valves or adjusting the guide vanes.

Die Offenlegungsschrift DE 10 2008 036 305 A1 beschreibt ein Verfahren, bei dem aus den Durchgangszeiten der einzelnen Verdichterschaufeln eine Leistungsaufnahme des Verdichters ermittelt wird. Dafür werden die realen Durchgangszeiten mit den idealen Modelldurchgangszeiten verglichen und deren Differenz als Folge der Durchbiegung der Verdichterschaufeln ausgewertet. Aus der Durchbiegung der Verdichterschaufeln lässt sich ein Verdichtermoment und dementsprechend mit der Verdichterdrehzahl eine Verdichterleistung berechnen. Im stabilen Betriebszustand stellt sich ein Gleichgewicht zwischen der Antriebsleistung und der Verdichterleistung ein. Eine Störung dieses Leistungsgleichgewichtes wird als beginnende Instabilität gewertet und das Annähern an die Pumpgrenze angezeigt.The publication DE 10 2008 036 305 A1 describes a method in which a power consumption of the compressor is determined from the transit times of the individual compressor blades. For this, the real transit times are compared with the ideal model transit times and their difference evaluated as a result of the deflection of the compressor blades. From the deflection of the compressor blades can be calculated a compressor torque and, accordingly, with the compressor speed, a compressor power. In stable operating conditions, a balance between the drive power and the compressor power sets. A disturbance of this power balance is considered to be incipient instability and the approach to the surge line is indicated.

Gemäß der US 4,955,269 A ist es vorbekannt, zur Überwachung von Ermüdungserscheinungen, beispielsweise des Rotors einer Turbine, eine ruhende Belastung und ein schwingende Belastung zu messen.According to the US 4,955,269 A It is previously known, for monitoring fatigue, such as the rotor of a turbine, to measure a static load and a vibrating load.

Gemäß der US 4,518,917 A ist es vorbekannt, bei einer Turbine mehrere Abstandssensoren vorzusehen und den Abstand zwischen der Strömungsführung und den Schaufelspitzen der Turbine zu überwachen.According to the US 4,518,917 A It is already known to provide a plurality of distance sensors in a turbine and to monitor the distance between the flow guide and the blade tips of the turbine.

Gemäß der EP 1 980 719 A2 ist es vorbekannt, mittels eines Mikrowellenmeßsystems, den Zustand des Läufers einer Turbomaschine zu überwachen.According to the EP 1 980 719 A2 It is already known, by means of a Mikrowellenmeßsystems to monitor the condition of the rotor of a turbomachine.

Gemäß der US 4,573,358 A ist es vorbekannt, zum Aufzeigen von Vibrationen der Schaufelblätter einer rotierenden Maschine, eine Vielzahl von Sensoren um die Schaufelblätter anzuordnen und die Signale der Sensoren so zu kombinieren, dass ein Signal erhalten wird, das die Vibrationen charakterisiert.According to the US 4,573,358 A For example, in order to show vibrations of the blades of a rotating machine, it is previously known to arrange a plurality of sensors around the blades and combine the signals from the sensors to obtain a signal that characterizes the vibrations.

Gemäß der US 2009/078051 A1 ist es vorbekannt, zur Überwachung der Vibrationen der Schaufelblätter einer Turbine, einen Sensor versetzt gegenüber der Rotationsachse eines Prüfkopfes anzuordnen.According to the US 2009/078051 A1 it is previously known to arrange a sensor offset from the axis of rotation of a probe to monitor the vibrations of the blades of a turbine.

Der Zustand, wie Verschleiß, Verschmutzung, Erosion und Deformationen an den Verdichterschaufeln, sowie die Veränderung der Lage der Verdichterschaufeln, die sich bei jedem Triebwerksstart durch das Schaufelfußspiel neu ausrichten, haben Einfluss auf den gemessenen Durchgangszeitpunkt im Bezug auf den nominalen Durchgangszeitpunkt, auf deren Basis die Durchbiegung beziehungsweise die Auslenkung der Verdichterschaufeln ermittelt und auf den Betriebspunkt und dessen Abstand zur Pumpgrenze geschlossen wird. Die im Stand der Technik bekannten Verfahren können diesen Einfluss nicht erkennen und eliminieren, so dass es zu Fehlerkennungen kommen kann. Eine sichere Ermittlung des Betriebspunktes des Verdichters und damit des Pumpgrenzenabstands des Betriebspunktes ist nicht möglich.The condition, such as wear, fouling, erosion and deformation on the compressor blades, as well as the change in the position of the compressor blades, which reorient themselves at each engine start by the Schaufelfußspiel, have an influence on the measured passage time in relation to the nominal passage time, based on the deflection or the deflection of the compressor blades is determined and closed at the operating point and its distance from the surge line. The methods known in the prior art can not detect and eliminate this influence, so that it can lead to false detection. A reliable determination of the operating point of the compressor and thus the surge margin of the operating point is not possible.

Aufgabe der ErfindungObject of the invention

Die Aufgabe der Erfindung besteht darin, ein Verfahren sowie eine Vorrichtung bereitzustellen, mit denen eine sichere Erkennung des Betriebszustandes des Verdichters ermöglicht wird. Die Erkennung soll unabhängig von Einflüssen aus einem veränderten Zustand oder einer veränderten Lage der Verdichterschaufeln erfolgen.The object of the invention is to provide a method and a device with which a reliable detection of the operating state of the compressor is made possible. The detection should be independent of influences from a changed state or a changed position of the compressor blades.

Lösung der AufgabeSolution of the task

Die Aufgabe wird durch das Verfahren nach den Merkmalen des Patentanspruches 1 und der Vorrichtung nach Patentanspruch 6 gelöst. Vorteilhafte Weiterbildungen des Verfahrens und der Vorrichtung ergeben sich aus den jeweiligen Unteransprüchen.The object is achieved by the method according to the features of claim 1 and the device according to claim 6. Advantageous developments of the method and the device will become apparent from the respective dependent claims.

Beschreibung der ErfindungDescription of the invention

Der Zustand jeder einzelnen Verdichterschaufel, wie Verschleiß, Verschmutzung, Erosion und Deformationen definiert eine Abweichung von einem Idealzustand und hat Einfluss auf den realen, gemessenen Durchgangszeitpunkt. Als Durchgangszeitpunkt wird der Zeitpunkt verstanden, zu dem sich die Verdichterschaufelspitze wenigstens teilweise in einem Sensorbereich eines Sensors am Gehäuse des Verdichters befindet.The state of each individual compressor blade, such as wear, contamination, erosion and deformation defines a deviation from an ideal state and has an influence on the real measured transit time. The transit time is understood as the point in time at which the compressor blade tip is located at least partially in a sensor region of a sensor on the housing of the compressor.

Dabei kann beispielsweise der Eintritt in den Sensorbereich, der Durchgang durch den Sensorbereich oder der Austritt aus dem Sensorbereich verwendet werden, um den Durchgangszeitpunkt zu definieren.In this case, for example, the entry into the sensor area, the passage through the sensor area or the exit from the sensor area can be used to define the transit time.

Die Lage jeder einzelnen Verdichterschaufel am Laufrad kann sich bei jedem Start verändern. Da die Verdichterschaufeln im Laufrad spielend gelagert sind und erst beim Hochfahren des Verdichters bei einer Mindestdrehzahl aufgrund der Fliehkraft sich in der Führung selbstständig ausrichten und verankern, kommen diese Abweichungen von Betriebseinsatz zu Betriebseinsatz zu Stande. Auch bei Verdichtern mit fest am Laufrad angebrachten Verdichterschaufeln kann eine Lageveränderung beispielsweise durch Montagearbeiten erfolgen.The position of each compressor blade on the impeller may change each time it is started. Since the compressor blades are mounted playfully in the impeller and only at startup of the compressor at a minimum speed due to centrifugal self-align and anchor in the leadership, these deviations come from operational use to operational use to conditions. Even with compressors with fixedly attached to the impeller compressor blades, a change in position, for example by assembly work done.

Alle Abweichungen beeinflussen den Durchgangszeitpunkt und bedingen somit eine Differenz zwischen gemessenem und idealem Durchgangszeitpunkt. Als idealer Durchgangszeitpunkt wird jener Zeitpunkt verstanden, welcher sich bei einem idealen Laufrad mit äquidistanter Verdichterschaufelanordnung und unendlich steifen Verdichterschaufeln ohne Abweichungen aus Zustand und Lage ergeben würde.All deviations influence the transit time and thus cause a difference between the measured and ideal transit time. The ideal transit time is understood to mean the point in time which would result for an ideal impeller with equidistant compressor blade arrangement and infinitely stiff compressor blades without deviations from state and position.

Als Durchgangszeitpunkt wird der Zeitpunkt verstanden, zu dem sich die Verdichterschaufelspitze wenigstens teilweise im Sensorbereich des Sensors am Gehäuse des Verdichters befindet. Dabei kann beispielsweise der Eintritt in den Sensorbereich, der Durchgang durch den Sensorbereich oder der Austritt aus dem Sensorbereich definiert werden, um den Durchgangszeitpunkt zu definieren.The transit time is understood as the point in time at which the compressor blade tip is located at least partially in the sensor region of the sensor on the housing of the compressor. In this case, for example, the entry into the sensor area, the passage through the sensor area or the exit from the sensor area can be defined in order to define the transit time.

Die Abweichungen vom idealen Durchgangszeitpunkt der Verdichterschaufeln aus Zustand und Lage wird während eines Betriebseinsatzes des Verdichters als unveränderlich angenommen. Als Betriebseinsatz soll der Betrieb des Verdichters zwischen dem Anfahren und dem Abstellen, also dem Starten und Stoppen, verstanden werden.The deviations from the ideal transit time of the compressor blades from the state and position is assumed to be immutable during operation of the compressor. As an operational use of the operation of the compressor between the start and stop, so the starting and stopping, to be understood.

Hat der Verdichter beim Hochfahren die Mindestdrehzahl für das selbstständige Ausrichten der Verdichterschaufeln erreicht, richten sich die Verdichterschaufeln aus. Die Abweichungen der Verdichterschaufel vom Idealzustand hinsichtlich Zustand und Lage bleiben für diesen Betriebseinsatz konstant und können kompensiert werden. Erst beim Herunterfahren des Verdichters unter einer bestimmten Mindestdrehzahl lockern sich die Verdichterschaufeln entsprechend dem Fußspiel und die Abweichungen sind wieder unbestimmt..If the compressor has reached the minimum speed for self-aligning the compressor blades at startup, the compressor blades align. The deviations of the compressor blade from the ideal state in terms of condition and position remain constant for this operation and can be compensated. Only loosen when lowering the compressor below a certain minimum speed the compressor blades are corresponding to the foot play and the deviations are again undetermined ..

Die Erfindung stellt ein Verfahren bereit, mit dem eine sichere Erkennung des Betriebszustandes unabhängig vom Zustand und Lage der Verdichterschaufeln und dadurch ein optimaler Verdichterbetrieb ermöglicht wird. In erfindungsgemäß vorteilhafter Weise werden die Abweichungen vom Idealzustand jeder einzelnen Verdichterschaufel beim Hochfahren des Verdichters nach dem Erreichen der Mindestdrehzahl zum Ausrichten der Verdichterschaufeln ermittelt. Basierend auf dieser verdichterschaufelindividuell bestimmten Abweichung kann eine Korrektur der im Betrieb gemessenen Durchgangszeitpunkte jeder Verdichterschaufel erfolgen. Diese Korrektur ermöglicht eine genaue Bestimmung des Betriebszustands sowie einen wirküngsgradoptimalen Betrieb des Verdichters unterhalb der Pumpgrenze. Bei jedem Start des Verdichters werden die Abweichungen der Verdichterschaufeln gegenüber dem Idealzustand neu ermittelt, adaptiert und in die Auswertung einbezogen. Die so korrigierten gemessenen Durchgangszeitpunkte werden zur Ermittlung der Auslenkung infolge der Durchbiegung der Verdichterschaufel herangezogen, wobei erfindungsgemäß vorteilhaft nur die Durchbiegung infolge der Strömungsmechanik ermittelt wird. Eine vom Zustand und der Lage der Verdichterschaufeln unabhängige Betriebpunktermittlung wird erreicht.The invention provides a method with which a reliable detection of the operating state is made possible regardless of the state and position of the compressor blades and thereby an optimal compressor operation. In an advantageous manner according to the invention, the deviations from the ideal state of each individual compressor blade during startup of the compressor after reaching the minimum speed for aligning the compressor blades are determined. Based on this compressor blade individually determined deviation can be carried out a correction of the measured during operation passage times of each compressor blade. This correction allows an accurate determination of the operating state and a Wirkwirkgsgradoptimal operation of the compressor below the surge limit. At each start of the compressor, the deviations of the compressor blades are compared with the ideal state redetermined, adapted and included in the evaluation. The thus measured measured passage times are used to determine the deflection due to the deflection of the compressor blade, according to the invention advantageously only the deflection is determined as a result of the fluid mechanics. An independent of the condition and the position of the compressor blades operating point determination is achieved.

Die Erfindung stellt weiterhin eine Vorrichtung bereit, mit welcher die Abweichungen ermittelt werden und eine Korrektur der Durchgangszeitpunkte erfolgt. Die Vorrichtung beinhaltet wenigstens einen Sensor zur Anzeige des Durchgangs einer Verdichterschaufel, fortan Verdichterschaufelsensor genannt, und wenigstens einen Sensor zur Anzeige der Drehung des Laufrades, fortan Laufradsensor genannt. Der Verdichterschaufelsensor gibt ein Triggersignal aus, wenn sich eine Verdichterschaufel vorbeibewegt. Zur Verbesserung des Triggersignals kann an der Verdichterschaufelspitze eine Markierung oder ähnliches vorgesehen sein. Aus dem Signal wird der Durchgangszeitpunkt ermittelt. Der Laufradsensor gibt ein Triggersignal entsprechend der Drehung des Laufrades aus. Daraus kann beispielsweise die Drehzahl des Laufrades berechnet werden. Auch hier können entsprechende Markierungen vorgesehen sein. Um die Genauigkeit der Drehzahlerfassung zu erhöhen, können mehrere Markierungen vorgesehen sein, um während einer Umdrehung des Laufrades mehrere Triggersignale zu erfassen, um mögliche Drehzahlschwankungen genauer abzubilden. Jedoch wird im Allgemeinen eine Markierung ausreichen, da die Drehzahl äußerst geringen Drehzahlschwankungen aufgrund der Trägheit des Laufrades unterliegt.The invention further provides a device with which the deviations are determined and a correction of the passage times takes place. The apparatus includes at least one sensor for indicating the passage of a compressor blade, henceforth called a compressor blade sensor, and at least one sensor for indicating the rotation of the rotor, henceforth called impeller sensor. The compressor blade sensor outputs a trigger signal as a compressor blade passes. To improve the trigger signal, a marking or the like may be provided on the compressor blade tip. From the signal, the transit time is determined. The impeller sensor outputs a trigger signal corresponding to the rotation of the impeller. From this, for example, the speed of the impeller can be calculated. Again, appropriate markings may be provided. In order to increase the accuracy of the speed detection, several markings may be provided to detect a plurality of trigger signals during a revolution of the impeller to possible Reflect speed fluctuations more accurately. However, in general, one mark will suffice because the speed is subject to extremely low speed variations due to the inertia of the impeller.

Die Triggersignale der Sensoren sind mittels einer zentralen Zeitbasis zueinander bezogen, so dass eine genaue Zuordnung der Triggersignale von Laufrad und Verdichterschaufeln erfolgen kann. Demnach kann über den Bezug von Verdichterschaufelsensor und Laufradsensor ein Vergleich zwischen gemessenem und idealem Durchgangszeitpunkt für jede einzelne Verdichterschaufel erfolgen.The trigger signals of the sensors are related to each other by means of a central time base, so that an accurate assignment of the trigger signals of the impeller and compressor blades can take place. Accordingly, the comparison of the compressor blade sensor and the impeller sensor can be used to compare the measured and ideal transit time for each individual compressor blade.

Parallel zum realen Laufrad wird in erfindungsgemäß vorteilhafter Weise ein Verdichternominalmodell verwendet, welches das Laufrad mit den Verdichterschaufeln als ideales Laufrad mit äquidistanter Verdichterschaufelanordnung mit unendlich steifen idealen Verdichterschaufeln ohne Abweichungen aus Zustand und Lage abbildet. Das Verdichternominalmodell kann als ein Speicherfeld abgebildet werden, in dem Speicherzellen gleich der Anzahl der Verdichterschaufel vorhanden sind. Es wird dabei jeder individuellen Verdichterschaufel eine individuelle Speicherzelle zugeordnet. Mittels eines beliebigen Reglers, vorzugsweise eines PID-Reglers, wird das Verdichternominalmodell der gemessenen Drehzahl des Laufrades phasengleich angepasst, so dass ein direkter Vergleich zwischen realem Laufrad und dem idealen Laufrad, dargestellt durch das Verdichternominalmodell, möglich ist. Dadurch wird eine Speicherzellenrotation gleich der Rotation des realen Laufrades erreicht. Alternativ kann ein mit der Rotation des Laufrades synchronisierter Zähler verwendet werden, mit dem die individuelle Speicherzelle des Speicherfeldes angesprochen werden kann. Das Verdichternominalmodell liefert nun für jede am Verdichterschaufelsensor durchgehende individuelle Verdichterschaufel den individuellen.idealen Durchgangszeitpunkt, also die Zeit, die eine geometrisch ideale und unendlich steife Verdichterschaufel am Sensor erzeugen würde. Die Differenz aus idealem Durchgangszeitpunkt und dem real am Verdichter gemessenen Durchgangszeitpunkt der jeweiligen Verdichterschaufel ergibt die Abweichung, also den relativen Durchgangszeitpunkt. Dafür ist in der erfindungsgemäßen Vorrichtung ein Differenzierer vorgesehen, um die entsprechende Operation durchzuführen. Der relative Durchgangszeitpunkt ist für den Idealfall gleich null und setzt sich im Realfall aus einer zustands- und lagebedingten Abweichung und dem eigentlichen Nutzsignal, also der strömungsmechanisch bedingten Abweichung, zusammen.Parallel to the real impeller, a compressor nominal model is used in accordance with the invention, which images the impeller with the compressor blades as an ideal impeller with equidistant compressor blade arrangement with infinitely rigid ideal compressor blades without deviations from condition and position. The compressor nominal model may be modeled as a memory array in which memory cells equal to the number of compressor blades are present. Each individual compressor blade is assigned an individual memory cell. By means of any regulator, preferably a PID controller, the compressor nominal model of the measured rotational speed of the impeller is adjusted in phase, so that a direct comparison between the real impeller and the ideal impeller, represented by the compressor nominal model, is possible. As a result, a memory cell rotation equal to the rotation of the real impeller is achieved. Alternatively, a synchronized with the rotation of the impeller counter can be used, with which the individual memory cell of the memory array can be addressed. The compressor nominal model now provides for each individual compressor blade passing through the compressor blade sensor the individual ideal transit time, that is, the time that a geometrically ideal and infinitely rigid compressor blade would produce at the sensor. The difference between the ideal transit time and the actual transit time of the respective compressor blade measured at the compressor gives the deviation, ie the relative transit time. For this purpose, a differentiator is provided in the device according to the invention in order to carry out the corresponding operation. The relative transit time is equal to zero for the ideal case and, in the real case, is composed of a state-related and position-dependent deviation and the actual useful signal, ie the flow-related deviation.

Bei sehr geringer Verdichterdrehzahl, beispielsweise im Leerlaufzustand oder beim Starten der Triebwerke kann der strömungsmechanisch bedingte Anteil der Abweichung als vernachlässigbar gering angesehen werden, so dass die zustands- und lagebedingte Abweichung überwiegt. Diese zustands- und lagebedingte Abweichung wird verdichterschaufelindividuell einem Verdichteradaptionsmodell zugeordnet, wobei das Verdichteradaptionsmodell analog zum Verdichternominalmodell entsprechend gleich viele Speicherzellen aufweist. Dazu ist in der Vorrichtung erfindungsgemäß neben dem Verdichternominalmodell das Verdichteradaptionsmodell mit einer Umschalteinheit integriert, mit welcher zwischen Arbeitsmodus und Lern-beziehungsweise Adaptionsmodus umgeschaltet wird. Wenn der Adaptionsmodus freigegeben ist, beispielsweise durch Drehzahlschwellen des Laufrades, kann die Adaption erfolgen. Im Arbeitsmodus nach dem Hochlaufen und dem Betrieb des Strahltriebwerks werden die verdichterschaufelindividuellen zustands- und lagebedingten Abweichungen aus dem Verdichteradaptionsmodell verwendet, um den relativen Durchgangszeitpunkt der jeweiligen Verdichterschaufel zu einem korrigierten relativen Durchgangszeitpunkt zu korrigieren, so dass nur noch der strömungsmechanisch bedingte Anteil zur Berechnung der Auslenkung der Verdichterschaufel berechnet wird. Die im Verdichteradaptionsmodell abgelegten zustands- und lagebedingten Abweichungen können als Abstand oder als Faktor in Form einer Zeit, eines Weges oder eines Winkels und so weiter hinterlegt sein. Zur Korrektur der zustands- und lagebedingten Abweichungen jeder individuellen Verdichterschaufel kann der gemessene Durchgangszeitpunkt oder der daraus berechnete relative Durchgangszeitpunkt herangezogen werden. Weiterhin wird die Laufraddrehzahl beziehungsweise die Tangentialgeschwindigkeit der Verdichterschaufelspitzen verwendet, um eine absolute Abweichung als Weg oder Winkel gegenüber dem Idealzustand zu berechnen. Weiterhin können geometrische Parameter des Verdichters und dessen Bestandteile in die Auswertung einbezogen werden. In vorteilhafter Weise kann das Verdichternominalmodell mit dem Verdichteradaptionsmodell zusammengefasst werden.At very low compressor speed, for example, in the idling state or when starting the engines, the flow-mechanical component of the deviation can be regarded as negligible, so that the state and conditional deviation prevails. This condition-related and position-dependent deviation is assigned to a compressor adaptation model in a compressor-specific manner, with the compressor adaptation model corresponding to the compressor nominal model correspondingly having the same number of memory cells. For this purpose, in the device according to the invention, in addition to the compressor nominal model, the compressor adaptation model is integrated with a switching unit with which switching is made between working mode and learning or adaptation mode. If the adaptation mode is enabled, for example by speed thresholds of the impeller, the adaptation can take place. In the work mode after run-up and operation of the jet engine, the compressor blade individual state and positional deviations from the compressor adaptation model are used to correct the relative transit time of the respective compressor blade to a corrected relative transit time, such that only the flow-mechanical fraction calculates the deflection the compressor blade is calculated. The state and location-related deviations stored in the compressor adaptation model can be stored as a distance or as a factor in the form of a time, a path or an angle and so on. For the correction of the conditional and positional deviations of each individual compressor blade, the measured transit time or the relative transit time calculated therefrom can be used. Furthermore, the impeller speed or tangential velocity of the compressor blade tips is used to calculate an absolute deviation as the path or angle from the ideal condition. Furthermore, geometric parameters of the compressor and its components can be included in the evaluation. Advantageously, the compressor nominal model can be combined with the compressor adaptation model.

Da die Auslenkung der Verdichterschaufel in Abhängigkeit vom Massestrom nicht monoton ist, sondern ein Maximum unterhalb der Pumpgrenze aufweist, ist die aus der Auslenkung berechnete Verdichterleistung zweideutig. Dieses Problem wird dadurch gelöst, dass die Änderung der Auslenkung während Betriebspunktänderungen beobachtet wird. Prinzipiell kann die Betriebspunktänderung durch die zwangsweise Modulation des Brennstoffmassenstroms erfolgen. Dies ist jedoch nicht erforderlich, da der Brennstoffmassenstrom sowohl durch Schubhebelverstellungen durch den Luftfahrzeugführer, als auch durch Ausregelaktivitäten des Autopiloten ohnehin fortwährend variiert wird.Since the displacement of the compressor blade is not monotonous depending on the mass flow, but has a maximum below the surge limit, the compressor power calculated from the deflection is ambiguous. This problem is solved by observing the change in deflection during operating point changes. In principle, the operating point change by the forced Modulation of the fuel mass flow done. However, this is not necessary, since the fuel mass flow is varied continuously both by thrust lever adjustments by the pilot as well as by Ausregelaktivitäten of the autopilot anyway.

Aus diesen Informationen zum korrigierten relativen Durchgangszeitpunkt, Verdichterschaufelauslenkung und deren Verlauf zusammen mit der Kenntnis über Verdichterdrehzahl, Gesamttriebwerksdruckdifferenz kann auf den momentanen Betriebspunkt des Verdichters und damit auf den momentanen Abstand des Betriebspunktes von der Pumpgrenze geschlossen werden.From this information on the corrected relative transit time, compressor blade deflection and their course together with the knowledge of compressor speed, total engine pressure difference can be concluded that the current operating point of the compressor and thus the instantaneous distance of the operating point of the surge line.

Zur Verbesserung des erfindungsgemäßen Verfahrens kann eine Sensorkonfiguration verwendet werden, welche aus wenigstens zwei Verdichterschaufelsensoren und einem Laufradsensor besteht. Bei Vorhandensein nur eines Sensors können Blattschwingungen mit gleicher oder vielfacher Frequenz der Laufradfrequenz nicht erkannt werden. Durch die Erhöhung der Anzahl der Verdichterschaufelsensoren und deren unregelmäßige Verteilung über dem Verdichterumfang können auch diese Frequenzen erfasst werden. Es können Sensoren mit verschiedenen Funktionsweisen verwendet werden. Eine Kombination aus Durchgangssensitivität und Abstandssensitivität würde jedoch den Vorteil mit sich bringen, eine Spaltregelung für die Verdichterschaufeln zu ermöglichen.To improve the method according to the invention, a sensor configuration can be used, which consists of at least two compressor blade sensors and an impeller sensor. If only one sensor is present, blade oscillations with the same or multiple frequency of the impeller frequency can not be detected. By increasing the number of compressor blade sensors and their irregular distribution over the compressor circumference also these frequencies can be detected. Sensors with different functions can be used. However, a combination of transmission sensitivity and distance sensitivity would have the advantage of allowing gap control for the compressor blades.

Als Erweiterung des erfindungsgemäßen Verfahrens bietet sich die Berechnung des Anströmwinkels aus den vorliegenden Informationen an. Der berechnete Anströmwinkel wird kontinuierlich in ein beschreibbares Kennfeld eingetragen und so im Laufe der Betriebszeit des Triebwerkes dessen Betriebskennfeld ermittelt und festgehalten. Es ist zudem aus Experimenten am Prüfstand bekannt, bei welchem Anströmwinkel es zur Strömungsablösung und somit zum Verdichterpumpen kommt, so dass die Pumpgrenze fest im Kennfeld hinterlegt wird. Durch nichtflüchtiges Speicherverhalten bleiben diese Informationen auch nach Herunterfahren des Triebwerks erhalten, so dass eine feste Sicherheitsschwelle für den stabilen Betrieb des Strahltriebwerks vorliegt.As an extension of the method according to the invention, the calculation of the angle of attack from the available information offers. The calculated angle of incidence is continuously entered into a writable map and thus determined and recorded during the operating time of the engine whose operating map. It is also known from experiments on the test bench, at which angle of attack it comes to the flow separation and thus to the compressor pumping, so that the surge limit is firmly stored in the map. Non-volatile memory behavior keeps this information even after the engine has been shut down, so that there is a fixed safety threshold for the stable operation of the jet engine.

Das erfindungsgemäße Verfahren kann auf eine Verdichterstufe oder auf mehrere beziehungsweise ausgewählte Verdichterstufen angewendet werden, die besonders von der Gefahr des Pumpens betroffen sind.The method according to the invention can be applied to a compressor stage or to several or selected compressor stages, which are particularly affected by the risk of pumping.

Das erfindungsgemäße Verfahren ist geeignet, nicht nur Verdichterinstabilitäten durch verdichterschaufelweise Betrachtung zu erkennen, sondern auch zwischen rotierenden Ablösungen und Verdichterschaufelflattern zu unterscheiden, da rotierende Ablösungen im Gegensatz zu Verdichterschaufelflattern umlaufen. Das erfindungsgemäße Verfahren erlaubt eine optimale Einstellung der Aktuatoren eines Verdichters, da der tatsächliche Betriebszustand des Verdichters und die Lage der Pumpgrenze bekannt sind. Der Verdichter kann somit wirkungsgradoptimal betrieben werden, ohne dass in den instabilen Betriebszustand hineingefahren werden muss. Als Folge davon wird der spezifische Verbrauch gesenkt. Der Verdichter kann beispielsweise leichter und auch kleiner ausgelegt werden.The method of the present invention is capable of not only detecting compressor instabilities by compressor blade viewing, but also distinguishing between rotating separations and compressor blade flutter as rotating separations circulate unlike compressor blade flutter. The inventive method allows an optimal adjustment of the actuators of a compressor, since the actual operating state of the compressor and the position of the surge limit are known. The compressor can thus be operated with optimum efficiency, without having to be driven into the unstable operating state. As a result, the specific consumption is lowered. The compressor can be designed, for example, lighter and smaller.

Das erfindungsgemäße Verfahren bedarf nicht des Anfahrens an die Pumpgrenze, um deren Lage bestimmen zu können. Als Folge davon wird die Sicherheit erhöht.The method according to the invention does not require the approach to the surge line in order to be able to determine its position. As a result, safety is increased.

Das erfindungsgemäße Verfahren adaptiert laufend das Betriebskennfeld, so dass der Betrieb des Verdichters fortlaufend an seinen Alterungszustand angepasst wird. Als Folge davon sinkt der spezifische Verbrauch. Sollte es beispielsweise zu einer Verdichterinstabilität kommen, welche durch das Verfahren erkannt werden kann, wird dieses Verhalten im Betriebskennfeld durch Anpassen der Pumpgrenze korrigiert.The method according to the invention continuously adapts the operating map, so that the operation of the compressor is continuously adapted to its aging state. As a result, the specific consumption decreases. If, for example, a compressor instability occurs, which can be detected by the method, this behavior is corrected in the operating map by adjusting the surge limit.

Das erfindungsgemäße Verfahren prädiziert das Ausfallverhalten des Kompressors, so dass unplanmäßige Wartungen vermieden werden und die verfügbare Lebensdauer bekannt ist. Als Folge davon werden Betriebskosten, Wartungskosten, Konventionalkosten und Lagerhaltungskosten gesenkt und die Verfügbarkeit erhöht.The method according to the invention predicts the failure behavior of the compressor so that unplanned maintenance is avoided and the available service life is known. As a result, operating costs, maintenance costs, conventional costs and storage costs are reduced and availability is increased.

Das erfindungsgemäße Verfahren ist zudem kompatibel zu Verfahren der aktiven Spaltkontrolle, bei denen der Spalt zwischen den Verdichterschaufelspitzen und dem Gehäuse kontrolliert beziehungsweise geregelt wird. Weiterhin kann der Einsatz variabler Leitschaufeln und die Zapfluftabnahme optimiert werden.The method according to the invention is also compatible with methods of active gap control, in which the gap between the compressor blade tips and the housing is controlled or regulated. Furthermore, the use of variable vanes and the bleed air take-off can be optimized.

Ausführungsbeispielembodiment

Beispielhaft wird hier eine Ausführung der erfindungsgemäßen Vorrichtung dargestellt. In der dazugehörigen Figur zeigt:

  • FIGUR 1 : eine schematische Darstellung der Vorrichtung zum sicheren Betreiben eines Verdichters an der Pumpgrenze.
By way of example, an embodiment of the device according to the invention is shown here. In the accompanying figure shows:
  • FIGURE 1 : A schematic representation of the device for safe operation of a compressor at the surge line.

Die beispielhaft ausgestaltete Vorrichtung besteht aus einem Verdichterschaufelsensor (1), welcher entsprechend des Durchgangs einer Verdichterschaufel ein Triggersignal ausgibt und einem Laufradsensor (2), welcher entsprechend einer Umdrehung des Laufrades des Verdichters ein Triggersignal ausgibt. Mittels einer zentralen Zeitbasis (3) werden die beiden Triggersignale mit einem Zeitstempel versehen. Des Weiteren ist die Vorrichtung mit einem Verdichternominalmodell (4) und einem Verdichteradaptionsmodell (5) ausgestattet, welche mittels eines Reglers (6) zur Drehzahl des Laufrades phasengleich durchlaufen. Der Regler (6) nimmt einen Eingriff entsprechend der Regelabweichung vor. Das Verdichternominalmodell (4) als auch das Verdichteradaptionsmodell (5) besteht dazu aus mehreren Speicherzellen (4a, 5a), wobei die Anzahl der Speicherzellen jedes Modells der Anzahl der Verdichterschaufeln entspricht. Die Speicherzellen werden entsprechend der Drehzahl des Laufrades durch den Regler (6) phasengleich angesprochen. Das Verdichternominalmodell (4) gibt einen idealen Durchgangszeitpunkt entsprechend der aktuellen Verdichterschaufel aus, welches in einem Differenzierer (7) mit dem gemessenen Durchgangszeitpunkt verglichen wird und einen relativen Durchgangzeitpunkt ausgibt. Danach werden die in einem Lemmodus adaptierten Zustands- und Lageabweichungen der jeweiligen Verdichterschaufel aus dem Verdichteradaptionsmodell (5) mit dem relativen Durchgangszeitpunkt verrechnet. Damit das Verdichteradaptionsmodell (5) adaptiert werden kann, ist ein Schalter (8) vorgesehen, welcher bei einer erfüllten Bedingung (9) in einen Adaptionsmodus umschaltet. Ist die Bedingung (9) nicht erfüllt, wird die Vorrichtung im Arbeitsmodus betrieben. Die Vorrichtung gibt wenigstens eine Betriebspunktinformation aus, die aus dem korrigierten relativen Durchgangszeitpunkt und weiteren Größen in einer Auswerteeinheit (10) berechnet wurde.The exemplary configured device consists of a compressor blade sensor (1) which outputs a trigger signal corresponding to the passage of a compressor blade and an impeller sensor (2) which outputs a trigger signal corresponding to one revolution of the impeller of the compressor. By means of a central time base (3) , the two trigger signals are provided with a time stamp. Furthermore, the device is equipped with a compressor nominal model (4) and a compressor adaptation model (5) which run through in phase by means of a controller (6) to the speed of the impeller. The controller (6) performs an intervention according to the control deviation. For this purpose, the compressor nominal model (4) as well as the compressor adaptation model (5) consists of a plurality of memory cells (4a, 5a), the number of memory cells of each model corresponding to the number of compressor blades. The memory cells are addressed in phase according to the speed of the impeller by the controller (6) . The compressor nominal model (4) outputs an ideal transit time corresponding to the current compressor blade, which is compared in a differentiator (7) with the measured transit time and outputs a relative transit time. Thereafter, adapted in a Lemmodus state and position deviations of the respective compressor blade from the compressor adaptation model (5) are offset with the relative transit time. So that the compressor adaptation model (5) can be adapted, a switch (8) is provided, which switches over into an adaptation mode when a condition (9) is met . If condition (9) is not fulfilled, the device is operated in working mode. The device outputs at least operating point information calculated from the corrected relative transit time and other quantities in an evaluation unit (10) .

In einer alternativen Ausgestaltung der Vorrichtung kann das Verdichternominalmodell (4) durch eine Funktion ersetzt werden, die den idealen Durchgangszeitpunkt in Abhängigkeit der Laufraddrehzahl ausgibt, da diese für alle Verdichterschaufeln und der Modellannahme des idealen Laufrades gleich ist.In an alternative embodiment of the apparatus, the compressor nominal model (4) may be replaced by a function which outputs the ideal transit time in dependence on the impeller speed, since this is the same for all compressor blades and the model impeller of the ideal impeller.

In einer alternativen Ausgestaltung der Vorrichtung kann das Verdichteradaptionsmodell (5) durch ein Kennfeld ersetzt werden, dessen Kennfeldpunkte diskret angesprochen werden können und die Abweichung der jeweiligen Verdichterschaufel ausgeben. Die Kennfeldpunkte können beispielsweise mittels eines mit dem Laufrad synchronisierten Zählers erfolgen.In an alternative embodiment of the device, the compressor adaptation model ( 5) can be replaced by a characteristic map whose characteristic diagram points can be addressed discretely and output the deviation of the respective compressor blade. The map points can be done for example by means of a synchronized with the impeller counter.

Aufstellung der verwendeten BezugszeichenList of used reference numbers

11
VerdichterschaufelsensorCompressor blade sensor
22
Laufradsensorwheel sensor
33
Zeitbasistime basis
44
VerdichternominalmodellCompressor nominal model
4a4a
Speicherzellememory cell
55
VerdichteradaptionsmodellCompressor adaptation model
5a5a
Speicherzellememory cell
66
Reglerregulator
77
Differenziererdifferentiator
88th
Schalterswitch
99
Bedingungcondition
1010
Auswerteeinheitevaluation

Claims (8)

  1. Method for ascertaining the operating point of a compressor with at least one impeller, with compressor blades attached to the impeller, a housing and at least two sensors (1, 2), wherein a calculation of the deflection of the compressor blades is performed, on the basis of which the operating point and its distance from the pumping limit are ascertained by times at which the compressor blades pass by a sensor (1, 2) being measured and a signal that is representative of the rotational speed of the compressor impeller being ascertained, characterized in that, during a learning or adaptation mode, compressor-blade-specific, state- and position-induced deviations from an ideal state are ascertained by compressor-blade-specific passing times being measured and compared with ideal passing times, and in that, during a working mode, compressor-blade-specific passing times are measured and corrected by the ascertained state- and position-induced deviations.
  2. Method according to Claim 1, characterized in that the compressor-blade-specific, state- and position induced deviations of the compressor blades are ascertained during the starting up of the compressor after alignment of the compressor blades.
  3. Method according to one of the preceding claims, characterized in that the ascertainment of the compressor-blade-specific, state- and position-induced deviations is performed after reaching a minimum rotational speed of the impeller.
  4. Method according to one of the preceding claims, characterized in that the compressor-blade-specific, state- and position-induced deviations are stored as a distance or as a factor, in the form of a time, a displacement or an angle.
  5. Method according to one of the preceding claims, characterized in that the compressor-blade-specific, state- and position-induced deviations are stored during an adaptation mode in a compressor adaptation model (5) and are read out in a working mode.
  6. Apparatus for ascertaining the operating point of a compressor, with at least one compressor blade sensor (1), at least one impeller sensor (2), a device for presetting the system time, wherein at least one memory array is integrated, characterized in that the at least one memory array has a number of memory cells (4a, 5a) equal to the number of compressor blades to be monitored, wherein a device for synchronizing the memory array with the impeller rotation is provided, so that the measured passing times can be compared with ideal passing times and can be corrected with the compressor-blade-specific, state- and position-induced deviations.
  7. Device for ascertaining the operating point of a compressor according to Claim 6, characterized in that an evaluation unit (10) is provided, with which the operating point of the compressor, and correspondingly the distance from a pumping limit, can be determined, wherein the evaluation unit (10) has at least one input, by way of which corrected passing times are supplied.
  8. Device for ascertaining the operating point of a compressor according to Claim 6 or 7, characterized in that a switch (8) is provided, which can be switched to switch over between a learning mode and a working mode and an adaptation mode when a condition (9) is satisfied.
EP11813656.3A 2010-09-24 2011-09-19 Device and method for reliably operating a compressor at the pump threshold Not-in-force EP2619461B1 (en)

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US9835162B2 (en) 2017-12-05
WO2012095062A1 (en) 2012-07-19
DE102010046490A1 (en) 2012-03-29
US20130223981A1 (en) 2013-08-29

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