JP2013139821A - Blade tip clearance control of aircraft gas turbine engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a system for predicting an engine command that changes the rotation speed of an engine and adjusting, before the command, a blade tip clearance (CL) between rotary blade tips of an aircraft gas turbine engine and a surrounding shroud.SOLUTION: By expanding or shrinking the shroud 72 before the engine command, a step of deciding a time point for starting to adjust the tip clearance (CL) can be included. Data of an aircraft and/or aircraft crew can include communication between the aircraft crew and an air traffic controller or an air traffic control substitute device. The step of deciding the time point for starting to adjust the tip clearance (CL) can include a step of using a learning algorithm capable of using: the operation experience of the aircraft gas turbine engine; and/or the operation experience of the other jet engine of the aircraft including the aircraft gas turbine engine and/or the other aircraft.

Description

  The present invention relates to clearance control for maintaining a tip clearance between a rotor and a stator, and more particularly to such a method and system used to maintain a blade tip clearance in an aircraft gas turbine engine.

  Engine performance parameters such as thrust, fuel consumption rate (SFC), and exhaust gas temperature (EGT) margin are strongly dependent on the tip clearance between the turbine blade tip and a fixed seal or shroud surrounding the blade tip. The clearance between the turbine blade tip and the stationary seal or shroud should be minimized while avoiding friction between the turbine blade tip and the stationary seal or shroud. The problem with minimizing these tip clearances is that the blade tip length from the rotor center or engine axis, especially during transient operation, the shroud expands or contracts to accommodate blade length changes. Is to grow at a different rate than can be. This creates a condition known as friction where the blade tip contacts the shroud or excessive clearance, which can reduce engine performance and shorten blade and shroud life.

  These gaps are affected by thermal and mechanical growth of different amounts and speeds of the rotor and stator components. Mechanical growth is due to centrifugal forces and pressure changes that occur as a function of speed. Blade and rotor growth is generally much larger than stator growth. Stator thermal growth is generally greater than rotor thermal growth and occurs much more rapidly. Blade thermal growth is the fastest of the three. It is highly desirable to match these different growths while keeping the gap as tight as practicable throughout engine transient and steady state operation.

  The blade length from the rotor center to the blade tip grows in proportion to the square of the rotor angular velocity and in linear proportion to the temperature. Both of these effects are caused by increased fuel flow required for maneuvers such as climbing, certain parts of the descent / landing sequence and avoidance actions. Under active clearance control, the shroud is expanded by immersing the shroud or the turbine casing to which the shroud is attached in hot air, or shrinking by immersing the shroud or the turbine casing in cold air. Be made. Hot or cold air causes the shroud to expand or contract in a linear proportional state by the same physical process that grows the blade tip length from the rotor in linear proportion to temperature, namely thermal growth or contraction.

One method for matching these different growths, active clearance control, is a well-known method, which can be achieved from engine fans and / or compressors under steady state and high altitude cruise conditions. The flow of relatively cold or hot air is adjusted and blown onto the high and / or low pressure turbine casing to shrink the casing relative to the high and low pressure turbine blade tips. Air can flow or be blown onto other fixed structures such as flanges or pseudo-flanges used to support a shroud or seal around the blade tip.
U.S. Pat. No. 4,230,436 U.S. Pat. No. 4,304,093 U.S. Pat. No. 4,513,567 U.S. Pat. No. 4,856,272 U.S. Pat. No. 4,928,240 US Patent No. 4,999,991 US Patent No. 5,005,352 US Pat. No. 5,012,420 US Pat. No. 5,081,830 US Pat. No. 5,088,885 US Patent No. 5,090,193 US Patent No. 5,090,193 US Pat. No. 5,205,115 US Pat. No. 6,487,491 US Pat. No. 6,498,978 US Pat. No. 6,868,325 US Pat. No. 6,943,699 US Patent No. 7,013,239 US Pat. No. 7,043,348 US Patent Application Publication No. 2005/0017876 US Patent Application Publication No. 2005/0144274 US Patent Application Publication No. 2005/0149274 US Patent Application Publication No. 2006/0212281 US Patent Application Publication No. 2007/0101178 Commentary on the 1st International Civil Aviation Organization (CAR / DCA / 1) Meeting of Caribbean Civil Aviation Administrators held at Grand Cayman, Cayman Islands, October 8-11, 2002

  A method for adjusting a blade tip clearance between a rotating blade tip and a surrounding shroud in an aircraft gas turbine engine during flight predicts an engine command that changes engine rotational speed, such as ascent, and before that command Change the tip clearance. Changing the tip clearance can be based on monitored aircraft and / or aircraft occupant data indicating signs of engine commands. Aircraft and / or aircraft occupant data may include communications between the aircraft occupant and an air traffic controller or air traffic controller.

  The method may include determining when to begin adjusting the tip clearance by inflating or deflating the shroud during a period prior to the engine command to change engine speed. A learning algorithm can be used to correct the point in time when the tip gap begins to be adjusted. For the learning algorithm, the engine operating experience and / or other jet engine operating experience can be used. The other jet engines may be those of the aircraft that includes the aircraft gas turbine engine and / or other aircraft.

  Statistical methods can be used to determine when to begin adjusting the tip gap. The statistical method can be selected from the group consisting of statistical methods, correlation methods, multivariate statistical process analysis methods, and pattern recognition methods. This statistical method, Bayesian decision theory, neural network, fuzzy logic, Parzen window, nearest neighbor classification, hidden Markov models, linear and nonlinear discriminant analysis, Markov random fields, Boltzmann learning, classification and regression trees, and multivariate adaptive regression A pattern recognition method selected from the group consisting of:

  The method can be used as an override to the active gap control flow model used to schedule the desired blade tip gap.

  The above aspects and other features of the invention are described in the following description, taken in conjunction with the accompanying drawings.

  Shown schematically in cross-section in FIG. 1 is an exemplary embodiment of an aircraft gas turbine engine 10, such as a GE CFM56 series engine, with an active clearance control system 12. The engine 10 is in a downstream serial flow relationship, including a fan section 13 including a fan 14, a booster or low pressure compressor (LPC) 16, a high pressure compressor (HPC) 18, a combustion section 20, a high pressure turbine (HPT) 22, and a low pressure. It has a turbine (LPT) 24. A high pressure shaft 26 disposed around the engine axis 8 drives the HPT 22 to the HPC 18 and a low pressure shaft 28 drives the LPT 24 to the LPC 16 and the fan 14. The HPT 22 includes an HPT rotor 30 that has turbine blades 34 attached to its periphery. The blade 34 includes an airfoil 37 that extends radially outward from the blade platform 39 to the radially outer blade tip 82 of the blade 34 and airfoil 37 as shown in FIG.

  Middle air supply 100 and high air supply 102 (generally for CFM56 engines draw air from the fourth and ninth stages of HOC 18 respectively) as a source for heat control air 36. Used, the thermal control air 36 is supplied to a turbine blade clearance control device generally indicated by reference numeral 21 through first and second thermal control air supply pipes 110 and 112, respectively. The temperature of the heat control air 36 is controlled by adjusting the amounts of air extracted from the middle stage air supply source 100 and the higher stage air supply source 102 by the middle stage and high stage air valves 106 and 108, respectively. A distribution manifold system 50 surrounds the high pressure turbine 22. The manifold system 50 distributes the heat control air 36 to a plurality of annular spray tubes 60 surrounding the engine axis 8 as shown in FIGS.

  The time constant representing the growth rate of the blade radius R shown in FIG. 2 measured from the engine axis 8 (rotor center) to the blade tip 82 and the time constant representing the growth rate of expansion or contraction of the shroud 72 are as follows. This is markedly different when it shows a faster response to temperature. Disclosed herein is a method and system for predicting the onset of engine transients to initiate shroud expansion or contraction during a period DT prior to engine transients, where engine transients are generally With increasing or decreasing fuel flow and core rotor speed N2. The method is designed to inflate the shroud faster than the extension of the blade, thereby reducing the likelihood of friction while still maintaining the tip clearance between the blade tip and the surrounding shroud as small as possible, Thereby, high engine fuel efficiency is obtained.

  Shown in FIG. 2 is a first turbine stator assembly 64 attached to the radially outer casing 66 of the HPT 22 by front and rear case hooks 68, 70. The stator assembly 64 includes an annular split stator shroud 72 that is attached to the annular split shroud support 80 of the first turbine stator assembly 64 by front and rear shroud hooks 74, 76. Shroud segment 77. The shroud 72 surrounds the blade tip 82 of the turbine blade 34 of the rotor 30 and helps reduce flow leakage around the blade tip 82. In particular, the active clearance control system 12 is used to minimize the radial blade tip clearance CL between the blade tip 82 and the shroud 72 during cruise operation of the engine 10.

  Thermal control air impinges on and flows over the front and rear thermal control rings 84, 86, thus controlling the turbine blade tip clearance CL. The shroud segment 77 is supported radially outward by the front and rear thermal control rings 84, 86 and thus moves radially inward when the thermal control rings 84, 86 are cooled, and the thermal control rings 84, 86 are Moves radially outward when heated. Active clearance control can also be accomplished by blowing or impinging thermal control air, typically cooling air, on the outer or inner turbine casing that supports the stator shroud.

  The amount of heat control air 36 that is impinged to control the middle and high stage air valves 106, 108 and the turbine blade tip clearance CL shown in FIG. 2 is controlled by the controller 48 shown in FIG. In the exemplary embodiment of the active gap control system 12 shown herein, the thermal control air 36 is either heating air or cooling air. Herein, the controller 48 is shown as a digital electronic engine control system, often referred to as a fully automatic digital engine controller (FADEC). The controller 48 controls the turbine blade tip clearance CL by controlling the amount and temperature of the thermal control air 36 that impinges on the front and rear thermal control rings 84, 86 as desired.

  An algorithm or mathematically active gap control flow model, referred to below as ACC flow model 92, is used to control turbine blade tip gap CL, stored in controller 48 and executed in controller 48. The ACC flow model 92 is based on engine operating parameters and physical characteristics of various parts of the engine. The controller 48 sends valve position signals to the middle and high stage air valves 106, 108 based on the calculated ACC flow model 92 to control the total amount of heat control air 36. These air valves are gradually opened according to the valve position signal.

  In the exemplary embodiment shown herein, the ACC flow model 92 calculates or measures real-time or instantaneous blade tip clearance CL. This blade tip gap is referred to herein as the instantaneous gap. The gap model program CLM is executed as a background of FADEC after the engine is started. Calculating the instantaneous blade tip clearance CL is often referred to as synthesis and is generally based on a first set of engine operating parameters including the physical characteristics of various parts of the engine. The first set of engine operating parameters generally includes, but is not limited to, rotor and stator time constants, measured core rotor speed N2, air flow rate, temperature and pressure, time after throttle operation, and altitude. The instantaneous blade tip clearance can also be measured instead of being synthesized or calculated, or it can be a combination of both measurement and calculation methods.

  The desired blade tip clearance schedule, referred to herein as the required clearance DCL, is stored in the system. The required gap DCL can also be calculated or determined by the gap model program CLM based on a second set of engine operating parameters including physical characteristics of various parts of the engine. The required gap DCL is set to minimize fuel consumption while avoiding friction and the effects of friction, and to minimize the overall and cumulative adverse effects of friction. An exemplary dynamic blade tip clearance system, shown herein as a dynamic clearance intelligence system (DYCIS), is used to improve the blade clearance CL setting. DYCIS helps to control the blade tip clearance CL between the blade tip 82 and the shroud 72 surrounding the blade in the turbine hot section by optimally controlling the blade tip clearance under varying operating conditions. It is a dynamic probability system. The exemplary embodiment of DYCIS disclosed herein is stored in and executed within the controller 48. It can be part of the ACC flow model 92 that is used to control the turbine blade tip clearance CL, and it overrides the ACC flow model 92 or is referred to herein as the desired clearance DCL. It may be of a form that takes precedence over the tip clearance schedule.

  Predictive blade tip clearance control method 94, shown as stored in controller 48, can be used for an active clearance control system. Predictive blade tip clearance control method 94 controls ambient shroud 72 and blade tip clearance CL to avoid or minimize the effects of friction during engine transients such as acceleration during ascent. Within a sufficient amount of time to predict the onset of engine transient and adjust the thermal control air 36. The predictive blade tip clearance control method 94 can be part of DYCIS.

  DYCIS predicts when the blade tip clearance change should begin within a time sufficient to adjust the peripheral shroud 72 and avoid or minimize the effects of friction. DYCIS can also be used to determine the necessary or desired blade tip clearance, shown herein as required clearance DCL. The DYCIS 116 shown schematically in FIG. 5 includes a statistical method within the data analysis module 130 that analyzes data from sensors for active clearance control to generate performance data associated with the engine and aircraft. Data is used to provide direct insight into engine and aircraft operating conditions for the operation of the active clearance control system, DYCIS draws conclusions, and maintains the desired blade tip clearance during transient and non-transient engine operation. And allows appropriate measures to be taken to minimize friction or the effects of friction while maximizing engine fuel efficiency during non-transient engine operation.

  The data analysis module 130 uses at least one statistical technique or method that derives feasible conclusions from the data to predict engine transients and adjust the blade tip clearance CL. Numerous statistical analysis methods are known in the art and include, but are not limited to, correlation methods, multivariate statistical process analysis methods, and pattern recognition methods. Several pattern recognition methods are known in the art and are suitable for use in the data analysis module 130 for data analysis. These methods include, but are not limited to, Bayesian decision theory, neural networks, fuzzy logic, Parzen windows, nearest neighbor classification, hidden Markov models, linear and nonlinear discriminant analysis, Markov random fields, Boltzmann learning, classification and regression trees As well as multivariate adaptive regression. The exemplary embodiment of the data analysis module 130 shown herein employs a Markov chain structure to determine the necessary or desired blade tip clearance.

  The Markov chain structure includes a plurality of states 140. The output of module 130 is input to a gap control module 150, which includes in the gap model program CLM a schedule of the desired blade tip gap, referred to herein as the required gap DCL. A plurality of engine sensors 120 (1)-120 (M) provide input of a second set of monitored engine parameters to the Markov chain structure in module 130. The DYCIS control algorithm incorporates the elastic and thermodynamic properties of moving parts. DYCIS also utilizes a Bayesian learning algorithm that adjusts the surrounding shroud 72 and blade tip clearance CL and for thermal control within a time sufficient to avoid or minimize the effects of friction. The time at which the air 36 should be adjusted can be learned dynamically from its own experience and experience with other engines. DYCIS also knows from its own experience and other engine experience what blade tip clearance CL should be set both during steady state engine operation such as cruise and transient engine operation such as climbing. It can also be used to learn dynamically to maximize engine fuel efficiency and avoid or minimize the effects of friction.

  The second set of engine operating parameters and / or physical characteristics used as monitoring engine parameter inputs to the Markov chain structure in module 130 include, but are not limited to, measured core rotor speed N2, total air temperature TAT at ambient conditions, Altitude, compressor discharge static pressure PS3, variable stator vane angle set value (for example, in high pressure compressor), fan speed N1, exhaust gas temperature EGT, fan inlet total temperature T12, fan inlet total pressure PT2, compressor inlet temperature T25 , Fuel flow, longitudinal acceleration, vertical acceleration, EGT excess indication, and real-time or instantaneous blade tip clearance CL.

  A plurality of aircraft sensors 122 (1)-122 (N) provide input of a set of monitored aircraft indicator parameters to the Markov chain structure within module 130. The set of monitored aircraft indicator parameters may include, but is not necessarily limited to, aircraft occupant data such as push-to-talk (PPT) signals that indicate when a pilot or other occupant speaks on his microphone. it can. The set of monitored aircraft indicator parameters also includes the environmental conditions that the aircraft is experiencing during its flight, origin and destination, flight plan, airframe and engine identification, individual flight information such as occupant identification, humidity , Airborne dust, and data from other aircraft such as turbulence displays. DYCIS can use one or more of these parameters in a Markov chain structure to determine the necessary or desired blade tip clearance.

  The instantaneous blade tip gap CL is generally used as the current gap and is constantly compared with the required gap DCL, and the middle and high stage air valves 106, 108 are iterative until the two gaps essentially match. It is adjusted with. A predictive blade tip clearance control method and system for setting blade tip clearance and operating the active clearance control system 12 disclosed herein predicts changes in engine and / or aircraft operating conditions and is transient The engine operation is predicted and the gap is adjusted before the transient engine operation. Predictive blade tip clearance control methods and systems can be included in DYCIS or active clearance control systems.

  The most important transient engine operation for the tip clearance is the engine during the ascent and descent of the aircraft as shown in FIGS. 3 and 4 for the ascent of the aircraft between the first and second cruising altitudes A1 and A2. Acceleration and deceleration. By predicting engine acceleration and aircraft lift and starting to change the tip clearance before the engine acceleration and aircraft lift, maintain a smaller tip clearance during cruise conditions, thus improving engine efficiency and engine fuel consumption (SFC) can be improved. The cruise tip clearance is as small as possible, but is set large enough to avoid friction during transient engine operation, such as during engine acceleration and aircraft ascent. Current active clearance control systems begin to change the tip clearance when they detect changes in engine operating parameters such as those listed above. By predicting engine acceleration and aircraft lift and starting to change the tip clearance before the engine acceleration and aircraft lift, friction is still avoided or minimized while still operating with a smaller tip clearance during cruise conditions. Can be.

  The Markov chain structure in the module 130 is characterized by a plurality of states. Each state in the plurality of states has a table of transition probabilities associated with that state. Therefore, there are as many transition probability tables as there are states. The entry in the transition table corresponding to a particular state gives the probability of the state that if the Markov chain is in that particular state at time t, the Markov chain will transition to it at time t + Δt. Probabilities in the transition table are determined from historical data and can be made more accurate over time by incorporating data learned over various flights. The historical data can be from engine flight associated with a particular Markov chain, or the historical data can be from engines on the same aircraft and / or on other aircraft. The historical data may include aircraft data such as communications between the aircraft and / or its crew and the ground or other aircraft.

  FIG. 6 is a graphical representation of the flight of a two-engine (twin engine) aircraft, where the altitude is expressed in feet relative to the flight time in seconds. The graph of FIG. 6 shows that a flight can be represented in terms of time segments or adjacent time periods that exhibit common features. Graph 210 shows at least three such segments identified as ascending, cruise and descent, the longest of these three segments being cruise. Graph 220 shows turbine core speed N2 for the left engine of a two-engine aircraft in percent. Note that N2 is relatively constant or unchanged throughout the cruise segment. The graph 230 represents the exhaust gas temperature EGT in degrees Celsius for the left engine of an aircraft with two engines. Note that the EGT is also relatively constant or unchanged throughout the cruise segment.

  The turbine blade tip clearance CL can be reduced because there is no transient behavior in the EGT or N2, i.e. a relatively abrupt change during the cruise segment. Transient behavior in EGT or N2, i.e. a relatively abrupt change, does not appear to occur more rapidly than the time constant indicating the rate of blade tip growth relative to the rotor. Thus, prior to the ascending segment, the shroud 72 is expanded by flowing a relatively hot thermal control air 36 to heat the shroud 72 to accommodate blade growth measured from the engine axis 8 to the blade tip 82. And friction can be avoided. The recognition of the flight segments that the aircraft is driving and the predictability of when the aircraft will transition from one flight segment to another are important in determining the active clearance control protocol within DYCIS. is there. The state of the Markov chain structure and their transition probabilities determine the turbine blade tip clearance CL set by DYCIS for transition. The turbine blade tip clearance CL for the ACC system shown herein is the required clearance DCL.

  A given flight segment has a measure of stability associated with the flight segment. Stability should be understood to mean near-future predictability. A particular segment is said to be stable if the maximum value of the blade radius R measured from the engine axis 8 (rotor center) to the blade tip 82 can be accurately predicted within that particular segment. The cruise segment of the flight shown in FIG. 6 appears to be relatively stable because there are only small changes in EGT and core speed N2. The rising segment does not appear to be as stable as the cruise segment, with EGT and N2 showing some change. However, changes in EGT and N2 do not necessarily make the segment unstable.

  Determining stability is based on predictability, and predictability is based on the following three data sets: The first set is historical data, which is data that has been accumulated and analyzed for previous flights of a particular engine and / or a particular engine type. The second set is cueing data that affects the EGT or N2 or requests the blade radius R measured from the engine axis 8 (rotor center) to the blade tip 82. Data that roughly predicts near-future changes in flight operation that will affect any other variable or set of variables that will change. Some examples of queuing data include communications between aircraft pilots and ground controllers, such communications are probably (a) altitude change requests or requests, (b) May be related to messages from other aircraft telling poor flight conditions at the current altitude, and (c) accelerometer display of vibrations due to turbulence. These three examples of queuing data are merely examples, and other types of queuing data can be used. The third set is program data, which is data entered by a supervisory supervisor such as an air traffic controller or pilot / copilot. Such data includes, but is not limited to, flight plans and notams (aeronautical information), which includes information on the setting, condition or change of any air facility, service, procedure or fault, Knowing this information in a timely manner is essential for those involved in flight operations.

  FIG. 7 shows a gas turbine engine powered aircraft during level flight 301. In level flight 302, as the aircraft occupant increases the throttle angle, the rotor speed increases, the EGT increases, and the aircraft begins to rise through position 303 to its new flight altitude 304. The onset of the transient at 302 is predicted at 301 and there will be a period DT used to begin opening the shroud 7 before the blade tip begins to extend. In one embodiment of DYCIS, the occupant initiates a transmission 315 from the aircraft to the air traffic control (ATC) facility 310. Transmission 315 is an exemplary engine transient prediction event. The start of transmission is detected by the airborne module, which then performs two functions. The first of these functions initiates expansion of the shroud 72 as quickly as possible by flowing hot thermal control air 36 over the shroud 72 and initiates opening of the blade tip clearance CL. That is. The second of these functions is to start a timer that overrides any ACC control of the blade tip clearance CL and requires that the shroud 72 continue to expand. When the shroud is fully inflated, the system continues to prioritize ACC control of the blade tip clearance CL, and a predetermined time interval from the start of the aircraft-ATC communication by the detected occupant, which is an exemplary engine transient prediction event. Keep the shroud fully inflated until the time has elapsed.

  In another embodiment of the DYCIS shown in FIG. 8, the occupant 410 initiates a transmission 440 or a power hit to the ATC controller 460 by the wireless device 420 and the antenna 430 via the ATC communication facility 450 installed on the ground. This transmission start is detected by an onboard transmission start detector module 470. The output 475 of the transmission start detector module 470 is input to the airborne active clearance control module 490 and instructs the active clearance control module 490 to open the shroud 72 to its maximum opening as quickly as possible. The shroud 72 is opened to its maximum opening as quickly as possible by flowing hot thermal control air 36 over the shroud 72, thereby expanding or increasing the blade tip clearance CL. The output 475 is also input to the on-board timer module 480, which instructs the active gap control module 490 for a predetermined time interval after the transmission start detector module 470 detects the start of transmission. During that time, the shroud is kept open in its maximum inflated position.

  In yet another embodiment of the DYCIS shown in FIG. 9, the occupant 510 initiates an aircraft communication 540 to the ATC controller 560 via the wireless device 520 and antenna 530 or via the ground-based ATC communication facility 550. A communication 540 from the ATC controller 560 is received. In either case, the communication is sent as a baseband signal to the airborne signal conditioner module 570 which, if the baseband signal is an analog signal, transmits the baseband signal. Convert to digital stream. The baseband signal can be a digital stream from the beginning. Signal conditioner module 570 formats the digital stream into a data stream, which is then analyzed by analyzer module 580. The analyzer module 580 analyzes the occupant's communication content with respect to the ATC communication in an attempt to discover the intention of the near future transient activity. For example, if the analyzer module 580 detects that the occupant 510 is requested to change the altitude by the ATC controller 560, or if the analyzer module 580 detects that the ATC controller 560 instructs the altitude change, Since such commands are predictive of engine transients, the analyzer module 580 will instruct the active clearance control module 490 to open the shroud to its maximum opening as quickly as possible.

  Yet another embodiment of DYCIS shown in FIG. 10 is used for flight operation under free flight conditions, such as by using an automatic dependent monitoring broadcast (ADS-B) function, such as by using digital communications 640 with an aircraft. This is done with the air traffic control agency. ADS-B was explained at the 1st International Civil Aviation Organization Meeting (CAR / DCA / 1) of Caribbean Civil Aviation Administrators held at Grand Cayman, Cayman Islands, October 8-11, 2002 ing. ADS-B is described as a monitoring technology that allows usage that will have a common situational awareness regarding airspace and operation for both pilots and controllers. The ADS-B onboard system acts as an air traffic control agency that transmits aircraft identification, position, speed, and intent to other aircraft and ground air traffic control systems, and thus all of the US Air Traffic Control System (NAS) This makes it possible to recognize a common situation for properly equipped users. As shown in FIG. 10, ADS-B 610 communicates with other aircraft via wireless device 620 and antenna 630. The ADS-B communication is monitored by the airborne analyzer module 680, which detects the intention to change altitude and commands the active gap control module 690 to maximize the shroud as quickly as possible. Open to openness.

  FIG. 11 shows the blade tip clearance schedule between the maximum blade tip clearance value CLMAX and the minimum blade tip clearance value CLMIN with and without engine transient prediction, such as during aircraft ascent. It is a comparison. The blade tip clearance schedule is the blade tip clearance CL vs. core rotor for an active clearance control system that predicts the start of engine transients (labeled as predicted) and an active clearance control system that does not predict the start of engine transients (labeled unpredicted) This is shown as speed N2. The prediction method and system uses a lower blade tip clearance because it begins to expand the shroud during the period DT prior to the engine transient to reduce the probability of friction, which Maintaining the smallest possible tip clearance between the surrounding shrouds, thereby enabling high engine fuel efficiency. For the same engine, the blade tip clearance schedule for a clearance control system that predicts the start of an engine transient is lower than for a clearance control system that does not predict the start of an engine transient labeled as unpredicted. The prediction method and system can be retrofitted into an old engine. In the present prediction method and system, a prediction of shroud expansion can be incorporated in the period DT prior to the engine transient condition as a priority over the schedule of the blade tip clearance CL, after which the blade tip clearance CL is added to the active clearance control system ACC. Can be due to.

  While this specification has described what is considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention will become apparent to those skilled in the art from the teachings herein. It is therefore eager to protect all such modifications as fall within the spirit and scope of the appended claims. Accordingly, what is desired to be secured by Letters Patent application is the invention as described and identified in the claims appended hereto.

1 is a cross-sectional view of an aircraft gas turbine engine equipped with a predicted blade tip clearance control method and system. FIG. 2 is an enlarged cross-sectional view of a high-pressure turbine assembly showing a turbine rotor blade tip clearance and its control in the engine shown in FIG. 1. FIG. 2 is a graph of one embodiment of a predictive blade tip clearance control method for the engine shown in FIG. 1. The enlarged view of the prediction control method shown in FIG. FIG. 2 is a schematic diagram of a statistical method and system for analyzing data for the predictive blade tip clearance control method for the engine shown in FIG. 1. FIG. 2 is a graph diagram of segments identified by an exemplary embodiment of a predictive blade tip clearance control method for the engine shown in FIG. 1. 2 is a schematic diagram of an exemplary embodiment of flight using the predictive blade tip clearance control method for the engine shown in FIG. FIG. 2 is a schematic diagram of an exemplary embodiment of communications used during flight using the predictive blade tip clearance control method for the engine shown in FIG. 1. FIG. 4 is a schematic diagram of a second exemplary embodiment of communications used during flight using the predictive blade tip clearance control method for the engine shown in FIG. 1. FIG. 4 is a schematic diagram of a third exemplary embodiment of communications used during flight using the predictive blade tip clearance control method for the engine shown in FIG. 1. FIG. 2 is a graph comparing the blade tip clearance schedule of the exemplary embodiment of the predicted blade tip clearance control method for the engine shown in FIG. 1 with the blade tip clearance schedule of the non-predicted blade tip clearance control method.

8 Engine axis 10 Aircraft gas turbine engine 12 Active clearance control system 13 Fan section 14 Fan 16 Booster or low pressure compressor (LPC)
18 High pressure compressor (HPC)
20 Combustion Section 21 Turbine Blade Gap Control Device 22 High Pressure Turbine (HPT)
24 Low pressure turbine (LPT)
26 High Pressure Shaft 28 Low Pressure Shaft 30 HPT Rotor 34 Turbine Blade 36 Thermal Control Air 37 Airfoil 39 Blade Platform 48 Controller 50 Distribution Manifold System 60 Spray Pipe 64 Stator Assembly 66 Outer Casing 68 Front Case Hook 70 Rear Case Hook 72 Shroud 74 forward shroud hook 76 rear shroud hook 77 shroud segment 80 shroud support 82 blade tip 84 forward thermal control ring 86 rear thermal control ring 92 ACC (active gap control) flow model 94 predictive blade tip gap control method 100 middle stage air supply source 102 High stage air supply source 106 Middle stage air valve 108 High stage air valve 110 First heat control air supply pipe 112 Second heat control air supply pipe 116 DY CIS (Dynamic Gap Intelligence System)
120 (1) -120 (M) Multiple engine sensors 122 (1) -122 (N) Multiple aircraft sensors 130 Data analysis module 140 State 150 Gap control module 210 Graph 220 Graph 230 Graph 301 Horizontal flight 302 Horizontal flight 303 Position 304 Flight Altitude 310 ATC (Air Traffic Control) Facility 315 Transmission 410 Crew 420 Wireless Device 430 Antenna 440 Transmission 450 ATC (Air Traffic Control) Communication Facility 460 ATC Controller 470 Transmission Start Detector Module 475 Output 480 Timer Module 490 Gap Control Module 510 Crew 520 Radio Device 530 Antenna 540 Communication 550 ATC Communication Facility 560 ATC Controller 570 Signal Conditioner Module 580 Analyzer Module 590 Gap Control Module 610 ADS-B (automatic subordinate monitoring broadcast)
620 Radio device 630 Antenna 640 Digital communication 680 Analyzer module 690 Gap control module A1 First cruise altitude A2 Second cruise altitude CL Blade tip gap CLM gap model program DT period DCL Required gap EGT Exhaust gas temperature N2 Core rotor speed R Blade radius SFC fuel consumption rate

Claims (10)

A method for adjusting a blade tip clearance (CL) between a rotating blade tip (82) and a surrounding shroud (72) in an aircraft gas turbine engine (10) during flight comprising:
Predicting an engine command to change engine speed and changing the tip clearance (CL) prior to the command,
Method. Monitoring aircraft and / or aircraft occupant data indicative of the indication of the engine command;
Changing the tip clearance (CL) based on the monitored aircraft and / or aircraft occupant data;
The method of claim 1.   The method of claim 2, wherein the aircraft and / or aircraft occupant data further comprises communication between an aircraft occupant and an air traffic controller or an air traffic controller.   The method further includes determining when to begin adjusting the tip clearance (CL) by expanding or contracting the shroud (72) during a period (DT) prior to an engine command to change the engine speed. 4. The method according to any one of items 1 to 3.   5. The method of claim 4, further comprising the step of modifying the point in time when the tip clearance (CL) begins to be adjusted by using a learning algorithm.   6. The method of claim 5, further comprising using the aircraft gas turbine engine operating experience and / or other jet engine operating experience for the learning algorithm.   5. The method of claim 4, further comprising using a statistical method to determine when to begin adjusting the tip clearance (CL).   The method of claim 7, wherein the statistical method for determining when to begin adjusting the tip clearance (CL) is selected from the group consisting of statistical methods, correlation methods, multivariate statistical process analysis methods, and pattern recognition methods. .   Statistical methods for determining when to start adjusting the tip clearance (CL) include Bayesian decision theory, neural network, fuzzy logic, Parzen window, nearest neighbor classification, hidden Markov model, linear and nonlinear discriminant analysis, Markov random field The method of claim 7, further comprising a pattern recognition method selected from the group consisting of: Boltzmann learning, classification and regression trees, and multivariate adaptive regression.   Predicting an engine command to change the engine speed and changing the tip clearance (CL) prior to the command is an active clearance control flow model (92) used to schedule the desired blade tip clearance. The method according to any one of claims 1 to 9, further comprising the step of prioritizing.