Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
  • F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
  • F01D11/14—Adjusting or regulating tip-clearance, i.e. distance between rotor-blade tips and stator casing
  • F01D11/20—Actively adjusting tip-clearance
  • F01D11/24—Actively adjusting tip-clearance by selectively cooling-heating stator or rotor components
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D9/00—Stators
  • F01D9/06—Fluid supply conduits to nozzles or the like
  • F01D9/065—Fluid supply or removal conduits traversing the working fluid flow, e.g. for lubrication-, cooling-, or sealing fluids
• • 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
  • F05D2270/11—Purpose of the control system to prolong engine life
• • 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
  • F05D2270/20—Purpose of the control system to optimize the performance of a machine
• • 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
  • F05D2270/40—Type of control system
  • F05D2270/44—Type of control system active, predictive, or anticipative
• • 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
  • F05D2270/60—Control system actuates means
  • F05D2270/64—Hydraulic actuators
• • 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
  • F05D2270/702—Type of control algorithm differential

Definitions

• the invention relates to turbomachines and methods or devices for controlling valves controlling an air flow, and in particular LPTACC valves ("low pressure turbine active clearance command" in English according to the terminology used in aeronautics for active control of the games of the low pressure turbine), that is to say the valves which aim to control the clearance between a turbine blade and a housing arranged radially around.
• LPTACC valves low pressure turbine active clearance command
• the expansion of the elements depends on several parameters, including materials, assemblies, rotational speed, temperature, etc.
• the LPTACC valve can therefore affect the crankcase temperature.
• the game is modulated according to the phases of flight, engine speed, altitude ...
• a turbofan engine 10 for aerospace propulsion is shown in FIG. It comprises a fan 11 delivering a flow of air, a central portion is injected into a primary stream VP comprising a compressor 12 which supplies a turbine 14 driving the fan.
• the turbine 14 comprises a plurality of vanes 140 extending radially and is housed radially inside a housing 16.
• a control valve 20 which is preferably of the LPTACC type, is provided.
• Figure 1b schematically illustrates the architecture of the environment of this valve 20 and its active control.
• This control valve 20 makes it possible to continuously control a flow of air coming from the secondary vein, from a sample 18, and to direct it towards the casing 16 arranged facing the blades 140 of the turbine 14. sampling 18 communicates with a supply duct 22 which brings the flow of air to the control valve 20. A discharge duct 24 then brings this air from the control valve 20 to the housing 16.
• a calculation unit 40 receives in particular the value of the engine speed and calculates a flow control which is converted into a command in position. This position control is sent to an actuator 30 which controls the valve 20. Position sensors (not shown) allow a return to the computing unit 40.
• FIG. 1b it is a hydraulic actuator which drives a hydraulic servovalve.
• the link 41 between the computing unit 40 and the actuator 30 is electric.
• the link 31 between the actuator 30 and the valve 20 is hydraulic.
• the return link 21 between the control valve 20 and the calculation unit 40 is electric.
• the active control is mainly aimed at reducing the clearance at the top of turbine blade 14 to optimize the specific consumption, that is to say the amount of fuel required to produce a thrust of a Newton for one hour.
• One of the objectives of the control is to define an optimal air flow rate for the active control, making it possible to limit the clearance at the top of the blades 140 as much as possible while minimizing the amount of air taken from the blower, because the air flowing through this means does not contribute directly to the thrust provided by the turbomachine 10.
• This objective is mainly targeted during cruise phases ("cruise" in English, that is to say the steady state).
• the invention relates to turbomachine control valves 10 and associated methods.
• the elements and their references given in the introduction will be reused for the description below.
• control methods of the control valve 20 generally comprise the following steps implemented by the calculation unit 40:
• step E3 for determining a command in position from the flow control.
• the control in position is intended to allow the control of the valve 20, in particular via an actuator 30 if the latter is not integrated with the valve 20.
• control valve 20 oscillates around its equilibrium position.
• the amplitude of these oscillations is small compared to the value of the control, but the frequency is high compared to the thermal response of the housing 16.
• oscillations can represent up to two thirds of the total stroke of the valve 20 during a flight and thus cause premature wear of the valve 20.
• the Applicant has also noticed that the oscillations are not due to the airflow which could generate disturbances but are due to the step E2 of determination of the control in flow.
• the step E3 for determining the control in position of the valve directly follows the step E2.
• a cruise value Vc is now defined around which the engine speed oscillates at a frequency fo and an amplitude Ao (Ao being small compared to Vc, typically less than 5% of Vc).
• the frequency fo is about 1 Hz (variable depending on the turbomachines). Since, during the cruising phase, the control in position of the valve 20 is substantially proportional to the engine speed, this oscillation of the speed results in an oscillation of the position control.
• the engine speed can in particular be obtained by sensors measuring the rotational speed of the shaft of the low-pressure turbine.
• the rate change induced by these oscillations of the control in position is approximately 5%. Because of its value and frequency, such a change has no physical utility since the thermal response time of the housing 16 is slower.
• the invention proposes a control method comprising a determination step for the control valve 20 of a control in the filtered position of the oscillations of the engine speed around the cruising value Vc.
• the filtering uses a low-pass filter whose cutoff frequency is greater than a frequency associated with the thermal response time of the housing, to ensure that the filtering does not disturb the function of the valve.
• an adapted filtering makes it possible to suppress the noise of the signal and to optimize the management of the valve.
• the cumulative stroke of the valve can be divided by three on a flight, which increases its life.
• the filtering is carried out using a low pass filter, whose cutoff frequency fc is lower than the frequency of the oscillations fo, to mitigate them. More generally, the cutoff frequency fc is chosen to attenuate the oscillations during the entire cruising phase.
• the filtering provided in the method makes it possible to limit the influence of the oscillations on the control in position and thus to improve the life of the valve 20.
• the filtering can be performed on different signals but ultimately produces a similar result, namely that the position control is filtered oscillations of the engine speed.
• valves LPTACC that is to say intended to supply air to the housing to modify its expansion
• valves LPTACC that is to say intended to supply air to the housing to modify its expansion
• valves LPTACC any type of valve whose calculation unit which the pilot receives in engine speed data input and therefore applies to valves whose position oscillates in response to engine speed oscillations.
• the invention may have the following characteristics, taken alone or in combination:
• the determination step comprises the following substeps:
• the filtering is performed using a low-pass filter whose cutoff frequency fc is less than one frequency (fo) oscillations of the engine speed around the cruising value Vc,
• the filter is a first-order low-pass filter
• control valve is intended to supply air to a casing to modify its expansion and in which the cut-off frequency fc is greater than a frequency fr associated with the thermal response time of the casing
• the cut-off frequency fc is between 0.05 Hz and 0.15 Hz
• the method comprises a sub-method of deactivating the filtering step Ef implemented by the computing unit, said sub-method comprising the following steps:
• the method comprises a sub-method for activating the filtering step Ef implemented by the calculation unit, said sub-method comprising the following steps:
• the step of activating the filter (E63) is done if the altitude, the engine speed and the Mach each further verify a certain value
• the determination step comprises the following substeps:
• the invention also proposes a control system for a control valve of a turbomachine operating at engine speed at a cruising value Vc, said control valve being intended to supply air to a housing to modify its expansion, said system comprising a control valve and a calculation unit configured to implement the method as described above.
• the computing unit includes a data receiving interface, a processor capable of processing data, a memory (for storing data) and a data output interface.
• the computing unit comprises a filtration unit (typically the processor that executes operations), which performs the filtering operation.
• the invention also proposes a turbomachine comprising a system as described above.
• FIG. 1a illustrates the overall architecture of a turbomachine
• FIG. 1b illustrates the overall architecture of the flow control elements taken from the secondary vein and sent towards the casing opposite turbine blades according to the state of the art
• FIG. 2 illustrates in steps a mode of implementation of the invention
• FIG. 3 illustrates the block diagram architecture of a method for activating or deactivating the filter, complementary to the embodiment of FIG. 2,
• the filtering step Ef is applied to the control in the position resulting from the step E3, so that a command in the filtered position is obtained.
• the filtering is performed with a first-order low-pass filter having a unique cut-off frequency fc.
• the choice of filter type is based on the fact that the frequencies to be suppressed are much higher than the nominal behavior of the logic.
• the determination of the cut-off frequency fc is an important condition for obtaining effective filtering which does not uninhibitably slow down the control method.
• the response time of the filter was chosen by a compromise between two constraints. Indeed, this response time must be high enough to remove a maximum of oscillations without slowing down the system in unacceptable proportions from a point of view of the thermal response of the housing. Indeed, a frequency too low would filter the nominal value of the control and the control valve 20 would remain almost immobile.
• the frequency fo of the micro-oscillations was also estimated, which made it possible to determine a lower limit of the response time, and therefore an upper limit for the cut-off frequency fc.
• a cut-off frequency fc of between 0.05 and 0.15 Hz, or else 0.08 and 0.12 Hz or, more broadly, between 0.01 and 0.20 Hz, is chosen.
• the frequency fo is around 1Hz, which is quite far from the previous upper bounds for efficient filtering.
• cutoff frequencies fc in the latter range it is ensured to have response times lower than those of the housing 16.
• a filter application condition is primarily related to the cruising speed. For this, we check three indicators:
• the Mach that is to say, the ratio of the local velocity in a fluid on the speed of sound in the same fluid
• control valve 20 when the system requires a rapid reaction of the control valve 20, it is desired that the control is not slowed down by a filter (for example a pilot action, during take-off or landing or for example a sudden change of environment).
• a filter for example a pilot action, during take-off or landing or for example a sudden change of environment.
• the method additionally comprises a sub-method of deactivating the filter.
• FIG. 3 represents a block diagram indicating the different steps of this sub-method.
• a step E51 the gradient between two instants (that is to say the variation between two values at two times of a digital signal) of the command in position resulting from the step E3 is determined. This is not the filtered command.
• several cascade delay blocks can be used (the number of three is linked to the internal logic of the calculation unit 40, for which the iteration rate is 0.240s, ie 0.720s for the three iterations ).
• this gradient is compared with a deactivation threshold value Sg. More precisely, in order to overcome the questions of signs, the absolute value of this gradient is compared with the deactivation threshold value Sg.
• the filtering step Ef is deactivated if the gradient is greater than or equal to said threshold Sg.
• a threshold value is chosen which is between 0.5 and 2.5% per second, that is to say that at one second intervals the control varies between 0.5 and 2.5% of its original value.
• the threshold value is 1% for 0.72 seconds, or 1.4% per second.
• An interval of 1 and 2% per second may also be appropriate.
• a gradient above the threshold Sg means that it is not a micro-oscillation that is detected, but a relevant change for the system that can have an impact on the housing 16.
• the filtering stops and the system recovers its conventional operation.
• the analyzed value is the gradient of command and not the physical measurement given by the sensors: the solution would take into account the filtering (since the command in position was filtered) and would be too slow.
• the reactivation (or activation) of the filtering stage is also done under condition using another sub-process, also shown in FIG.
• steps E61, E62 similar to steps E51 and E52 respectively, the gradient is compared with an activation threshold value Sg '.
• a step E63 the filtering step Ef is activated if the gradient remains below the threshold Sg 'during a confirmation period T fixed.
• the additional conditions of the cruise phase (Mach, altitude and engine speed) are also analyzed here.
• Step E63 is misrepresented in Figure 3, since the drawn block outputs an activation condition, which is then preferably combined with the other activation conditions to effectively activate the filter.
• the filtering step Ef is applied to the engine speed data coming from the step E1, so that a control in the filtered position is again obtained.
• the step of determining a flow control E2 is then done from the filtered data relating to the engine speed.
• the filtering is preferably integrated in fact in the step E2 of determining a control in flow.
• Embodiments with activation and deactivation thresholds may also be implemented.
• step E2 It is also conceivable to apply the filtering step to the flow control from step E2.
• the step of determining the command in position E3 is then done from a control data in filtered flow. This embodiment is illustrated in FIG.
• Embodiments with activation and deactivation thresholds may also be implemented.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Control Of Turbines (AREA)

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• 2016
  • 2016-11-22 FR FR1661340A patent/FR3059042B1/fr active Active
• 2017
  • 2017-11-22 US US16/463,002 patent/US10995628B2/en active Active
  • 2017-11-22 CA CA3044429A patent/CA3044429A1/fr active Pending
  • 2017-11-22 WO PCT/FR2017/053207 patent/WO2018096264A1/fr unknown
  • 2017-11-22 EP EP17811651.3A patent/EP3545175B1/de active Active
  • 2017-11-22 CN CN201780076407.4A patent/CN110050106B/zh active Active

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