CN113482797A - Tandem type TBCC engine modal conversion control method and device - Google Patents

Tandem type TBCC engine modal conversion control method and device Download PDF

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CN113482797A
CN113482797A CN202110949089.6A CN202110949089A CN113482797A CN 113482797 A CN113482797 A CN 113482797A CN 202110949089 A CN202110949089 A CN 202110949089A CN 113482797 A CN113482797 A CN 113482797A
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CN113482797B (en
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席志华
张海波
胡晨旭
汪勇
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Nanjing University of Aeronautics and Astronautics
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K7/00—Plants in which the working fluid is used in a jet only, i.e. the plants not having a turbine or other engine driving a compressor or a ducted fan; Control thereof
    • F02K7/10—Plants in which the working fluid is used in a jet only, i.e. the plants not having a turbine or other engine driving a compressor or a ducted fan; Control thereof characterised by having ram-action compression, i.e. aero-thermo-dynamic-ducts or ram-jet engines
    • F02K7/16—Composite ram-jet/turbo-jet engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/62—Hybrid vehicles

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Abstract

The invention discloses a tandem type TBCC engine modal conversion control method. In the mode conversion process of the engine, the maximum state working point of a turbine component and the slow turning state working point are used as optimization boundaries, the optimal change curves of the total thrust, the total air flow, the fan conversion rotating speed, the opening degree of a rear variable-area bypass ejector and the opening degree of a mode conversion valve in the mode conversion process are obtained through optimization solution, then the engine is subjected to closed-loop control through the optimal change curves of three direct energies, namely the total thrust, the total air flow and the fan conversion rotating speed, and then the engine is subjected to open-loop control through the optimal change curves of the opening degree of the variable-area bypass ejector and the opening degree of the mode conversion valve. The invention also discloses a tandem type TBCC engine mode conversion control device. The invention uses the direct energy as the controlled quantity to carry out closed-loop control on the engine, and can effectively improve the stability, the safety and the speed of the conversion process.

Description

Tandem type TBCC engine modal conversion control method and device
Technical Field
The invention relates to a mode conversion control method of a turbine-based combined cycle engine (TBCC engine), in particular to a mode conversion control method of a tandem type TBCC engine.
Background
TBCC engine) is a new type of power system that combines the duty cycles of turbine engines and ramjet engines, has the advantages of flight envelope, conventional take-off and landing, and re-use, and is considered one of the ideal powers for future high-speed aircraft. According to the difference of relative positions of the turbine engine and the ramjet engine, the TBCC engine can be divided into a series connection type layout and a parallel connection type layout, and compared with the parallel connection type layout, the series connection type TBCC engine has the advantages of small windward area, compact structure and light weight. The mode conversion process is a transition mode for realizing mutual conversion between a turbine mode and a stamping mode of the TBCC engine, and how to realize smooth transition of thrust and air flow in the mode conversion stage is always the key point and difficulty of research on a tandem type TBCC control system.
In recent years, many scholars have been devoted to the research on TBCC engine modeling and modal transformation process control issues. The NASA research center developed a simulation that uses the hiteccc (high mach transient engine cycle code) tool to simulate a propulsion system. The intake system was tested to evaluate the method of performing a controlled intake mode transition for a combined cycle Propulsion system based on a turbomachine [ J.T.Cscan, T.J.Stueber, A turbine based combined cycle engine model and mode transition simulation based on HiTECC tool, in:48th AIAA/ASME/SAE/ASEE Joint prediction Conference and inhibition 2012, https:// doi.org/10.2514/6.2012-4149 ]. The steady-state modal transition problem of the serial variable cycle turbine-ramjet engine is solved by adopting a Newton-Raphson algorithm in Chengming of Beijing aerospace university. The algorithm studies a multi-objective multivariable target planning algorithm to ensure the stability of the Mode conversion of the series Turbo-ramjet engine [ C.Min, T.Hailong, Z.Zhili, Goal Programming for Stable Mode conversion in Tandem Turbo-ramjet Engines, Chinese Journal of Aeronautics.22(2009). https:// doi.org/10.1016/S1000-9361(08)60130-2 ]. Zhang Yang performed mode conversion performance analysis on a small series TBCC engine by using an air-breathing high Mach propulsion system simulation tool (HiMach). The algorithm achieves substantially smooth transitions of engine thrust and air flow, but does not take into account the speed of the transition [ M.Zhang, Z.Wang, Z.Liu, X.Zhang, Analysis of mode transition performance for a distance TBCC engine, in:52nd AIAA/SAE/ASEE Joint prediction Conference, 2016.https:// doi.org/10.2514/6.2016-4573 ]. The von haiong of Nanjing aerospace university aims at smooth transition of thrust and airflow in the mode conversion process, and an Improved ITLBO (Improved testing-Learning Based Optimization) algorithm is adopted to optimize the control law. However, the fuel flow of the main combustion chamber is controlled in an open loop manner, and has the disadvantages of weak interference suppression capability, low control accuracy and the like [ H.Feng, Research on Modeling and control method of series TBCC engine. Nanjing University of Aeronoutics and Astronautics,2019 ].
In summary, currently, for the research of the mode conversion phase control method of the TBCC engine, much attention is paid to the smooth transition of the thrust and the air flow, and no research is paid to the rapidity of the mode conversion process and the safety of the mode conversion process. The mode conversion control method is also limited to an open-loop control method or a closed-loop control method based on measurable state quantities such as pressure and rotation speed. Compared with the control mode, the control mode taking the direct energy (such as thrust, flow and the like) as the controlled quantity can be more direct on the basis of ensuring high noise immunity, and the requirement of stable transition of the thrust and the flow during the mode conversion period is effectively met.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects in the prior art and provides a tandem type TBCC engine mode conversion control method, which takes direct energy as controlled quantity to carry out closed-loop control on an engine and can effectively improve the stability, safety and speed of the conversion process.
The invention specifically adopts the following technical scheme to solve the technical problems:
a tandem type TBCC engine modal conversion control method is characterized in that in the engine modal conversion process, the maximum state working point and the slow vehicle state working point of a turbine component are used as optimization boundaries, and the total thrust F and the total air flow W in the modal conversion process are obtained through optimization solutiona1Fan conversion speed nl,corOptimum change curve of opening RVABI of rear variable-area bypass ejector and opening MSV of mode conversion valveLine, then total thrust F, total air flow Wa1Fan conversion speed nl,corThe three optimal change curves of the direct energy perform closed-loop control on the engine, and then the optimal change curves of the variable-area bypass ejector opening RVABI and the mode conversion valve opening MSV perform open-loop control on the engine; the optimization solution is specifically to solve the following first optimization model:
Figure BDA0003217980270000021
s.t.umin≤u≤umax
Figure BDA0003217980270000031
Figure BDA0003217980270000032
where u is the engine control variable and u is [ W ]fb,Wfa,A8,MSV,RVABI]，WfbFor the main fuel flow of the turbine combustion chamber, A8Is the area of the throat of the exhaust nozzle, WfaRVABI is the opening degree of the rear variable-area bypass ejector and MSV is the opening degree of the mode switching valve for boosting/stamping fuel flowmlFor fan surge margin, SmhFor the compressor surge margin, the subscripts "min" and "max" represent the minimum value and the maximum value, respectively, the subscript "ref" represents the command value, w1、w2、w3Is a target weight coefficient, modulo rotation time
Figure BDA0003217980270000033
ΔM＝MT-MC，MTAs turbine torque, MCFor compressor torque, nhIs the physical speed of the compressor, nlIs the actual speed of the fan, nl,idleIs the slow speed of the fan, nl,maxAt the maximum speed of the fan, J is the moment of inertia of the rotor, and P isTotal pressure, PsFor static pressure, far is the air-fuel ratio, T is the total temperature, subscript "4" represents the main combustion chamber exit cross-section, subscript "65" represents the mixing chamber exit cross-section, subscript "7" represents the boost/ram combustion chamber exit cross-section, and subscript "C1" represents the ram channel inlet cross-section.
Based on the same inventive concept, the following technical scheme can be obtained:
a tandem TBCC engine mode transition control device comprising:
the mode conversion control plan module is used for obtaining total thrust F and total air flow W in the mode conversion process by taking the maximum state working point and the slow turning state working point of the turbine component as optimization boundaries through optimization solution in the engine mode conversion processa1Fan conversion speed nl,corThe opening degree RVABI of the variable-area bypass ejector and the opening degree MSV of the mode conversion valve are subjected to open-loop control; the optimization solution is specifically to solve the following first optimization model:
Figure BDA0003217980270000041
s.t.umin≤u≤umax
Figure BDA0003217980270000042
Figure BDA0003217980270000043
where u is the engine control variable and u is [ W ]fb,Wfa,A8,MSV,RVABI]，WfbFor the main fuel flow of the turbine combustion chamber, A8Is the area of the throat of the exhaust nozzle, WfaRVABI is the opening of a rear variable-area duct injector and MSV is the die for boosting/stamping fuel flowFormula switching valve opening degree, SmlFor fan surge margin, SmhFor the compressor surge margin, the subscripts "min" and "max" represent the minimum value and the maximum value, respectively, the subscript "ref" represents the command value, w1、w2、w3Is a target weight coefficient, modulo rotation time
Figure BDA0003217980270000044
ΔM＝MT-MC，MTAs turbine torque, MCFor compressor torque, nhIs the physical speed of the compressor, nlIs the actual speed of the fan, nl,idleIs the slow speed of the fan, nl,maxThe maximum rotation speed of the fan, J is the rotational inertia of the rotor, P is the total pressure, and P issFor static pressure, far is the oil-gas ratio, T is the total temperature, subscript "4" represents the main combustion chamber outlet cross-section, subscript "65" represents the mixing chamber outlet cross-section, subscript "7" represents the boost/ram combustion chamber outlet cross-section, subscript "C1" represents the ram channel inlet cross-section;
engine controller for controlling total thrust F and total air flow Wa1Fan conversion speed nl,corThe three optimal change curves of the direct energy perform closed-loop control on the engine.
Preferably, the operating point of the slow-moving state of the turbine component as the optimization boundary is obtained by solving the following second optimization model:
minJ＝w4×F+w5×Wa2+w6×RM
Figure BDA0003217980270000051
in the formula, w4、w5、w6Is a target weight coefficient, nlIs the actual speed of the fan, nl,idleIs the slow rotation speed of the fan, far4Is the main combustion chamber gas-oil ratio, far4minIs the lean oil boundary oil-gas ratio of the main combustion chamber, P is the total pressure, PsFor static pressure, backflow margin
Figure BDA0003217980270000052
Subscript "4" represents the main combustion chamber outlet cross-section, subscript "65" represents the mixing chamber outlet cross-section, subscript "C1" represents the ram channel inlet cross-section, and subscript "C2" represents the ram channel outlet cross-section.
Further preferably, the second optimization model is solved by combining a hybrid penalty function method and a particle swarm optimization algorithm.
Preferably, said total thrust F and total air flow Wa1Measurable parameters are used as input and are estimated through an airborne model based on a neural network; the inputs to the onboard model are selected using stepwise regression analysis with total thrust F and total air flow Wa1The most relevant set of measurable parameters.
Further preferably, the airborne model is specified as follows:
P＝fBP(x)
Figure BDA0003217980270000053
wherein P represents total pressure, T represents total temperature, nl,corConversion of the speed of rotation of the fan, nh,corFor the converted rotating speed of the compressor, subscripts of 2, 22, 25, 3 and 6 respectively represent the sections of an air inlet channel outlet, a fan outlet, a compressor inlet, a compressor outlet and a combustion chamber outlet, subscript BP represents a BP neural network, and k-1 and k-2 respectively represent the first 1 moment and the first 2 moment of the current k moment.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
the mode conversion control scheme can safely, stably and quickly realize the control requirement of the mode conversion process, and can reduce the thrust and flow fluctuation possibly caused by a turbine windmill and a parking state, and after the mode conversion critical point is further optimized, the air flow of a turbine channel and the proportion of the thrust in the total amount can be reduced, and the backflow margin of the punching duct is improved by more than 70%; by adopting the technical scheme of the invention, the modal conversion time can be reduced by 75%, the thrust fluctuation amplitude can be reduced by 2.76%, and the air flow variation amplitude can be reduced by 1.75%.
Drawings
FIG. 1 is a graph of optimal fuel delivery for acceleration and deceleration of an engine; the reference numbers in the figures have the following specific meanings: 1-steady state oil supply curve; 2-optimum accelerated fuel delivery curve; 3-optimal deceleration fuel delivery curve; 4-limiting curve of oil supply amount of surge boundary of compressor; 5-limiting curve of oil supply amount of lean flameout boundary of engine; 6-maximum gas temperature before turbine oil supply limiting curve;
FIG. 2 shows the absolute value of the T _ stat value of the thrust F;
FIG. 3 is a graph of intake air duct inlet air flow Wa1Absolute value of T _ stat value of (1);
FIG. 4 is a control block diagram of one embodiment of a tandem TBCC engine mode transition control apparatus of the present invention;
5(a) and 5(b) are schematic diagrams for verifying the accuracy of the airborne model;
FIG. 6 is a comparison graph of the optimization effect of the mode conversion critical point;
7(a) -7 (h) are forward mode transition control plan optimization results;
FIGS. 8(a) -8 (h) are diagrams illustrating the optimization results of the reverse mode conversion control plan;
fig. 9(a) to 9(c) show the forward mode conversion control effect;
fig. 10(a) to 10(c) show the reverse mode conversion control effect.
Detailed Description
The technical scheme of the invention is explained in detail in the following with the accompanying drawings:
1. selecting the corresponding relation between the controlled quantity and the controlled quantity of the direct performance:
in the research of the direct performance control, correlation analysis of direct energy and model control quantity is firstly carried out, so that the corresponding relation between the control quantity and the controlled quantity during the direct energy closed-loop control can be further clarified. For a tandem TBCC engine, the adjustable inputs include: turbine combustor primary fuel flow (W)fb) Area of the throat of the nozzle (A)8) Boost/ramjet fuel flow (W)fa) Then variable area bypass ejector opening (RVABI), mode switching valve opening (MSV). During the mode conversion, the total thrust (F) and the total air flow (W) need to be ensureda1) Cannot generate large fluctuation, and can ensure stable operation of the engine, and the fan converts the rotation speed (n)l,cor) The working condition of the turbine engine in the mode conversion process can be reflected, so the direct performance controlled quantity to be selected comprises the following steps: f, Wa1，Sml，Smh，nl,cor(wherein, SmlFor fan surge margin, SmhCompressor surge margin); analyzing the corresponding relation between the controlled quantity and the controlled quantity, firstly, operating the TBCC engine model to the mode conversion starting point (the height H is 12.5km, the Mach number Ma is 2.1), and controlling the engine (W)fb,Wfa,A8RVABI, MSV) were increased by 1% each, the remaining amounts were kept constant, and the respective direct energies were varied as shown in table 1.
TABLE 1 TBCC Engine correlation analysis Table
Figure BDA0003217980270000071
From an analysis of table 1, it can be seen that,
a. the larger the correlation with F is WfaAnd A8；
b. And Wa1The greater the correlation is A8,Wfa；
c. And nl,corThe greater the correlation is Wfb；
d. And SmlThe greater the correlation is Wfb，Wfa，A8；
e. And SmhThe greater the correlation is Wfb；
f. And nl,corThe greater the correlation is Wfb。
Based on the above analysis, the correspondence relationship between the controlled amount and the controlled amount is selected. During the mode transition, the turbine engine is switched between (start-slow-maximum state), nl,corIs the most suitable controlled quantity for characterizing the process, and W with larger correlation is selectedfbControlling nl,cor(ii) a Meanwhile, in order to ensure the stable transition of the thrust and the air flow in the mode conversion process, W is selectedfaControl Wa1，A8Controlling F; RVABI and MSV pair SmlAnd SmhThe influence of the two executing mechanisms is small, and the regulation of the two executing mechanisms directly influences the speed of the mode conversion progress, so open-loop control is adopted. For stability in the mode conversion process, a direct performance control plan is designed, and a margin S is reservedml,SmhRM (RM is a backflow margin) is guaranteed.
In summary, the corresponding relationship between the controlled variable and the controlled variable of the direct performance of the design is shown in formula (1):
Figure BDA0003217980270000081
2. and (3) directly designing a performance control plan by mode conversion:
in the embodiment, a design work of a direct performance control plan is completed according to 2 steps of critical point optimization and process optimization by using a conventional turbine engine acceleration and deceleration control plan designation method as a reference:
2.1 optimizing mode conversion critical points:
when the mode conversion process proceeds to the turbine engine slow-start condition, a certain amount of airflow (about 48% of the total airflow) remains in the turbine passage and provides a partial thrust (about 37% of the total thrust). When the mode conversion is below the slow-moving state, because the turbine engine adopts open-loop control at the moment, the immunity is poor, the continuous reduction of the rotating speed is likely to bring about great shaking of the total air flow and the total thrust, and even the phenomenon of backflow of a punching duct is likely to occur, so that the stability of the mode conversion is influenced and the conversion quality is reduced. Based on the method, the working point of the turbine component in the slow turning state is defined as the mode conversion critical point in the mode conversion process, and the mode conversion critical point is selected. The mode conversion critical point is selected to aim at selecting the optimal combination of adjustable variables of the engine, so that the backflow margin of the stamping duct at the critical point is as large as possible, and the air flow and the generated thrust of the turbine channel are as small as possible, thereby being beneficial to improving the safety of work below a slow vehicle, reducing the mode conversion time below the slow vehicle, and reducing the influence of factors such as uncontrollable rotating speed and environment on the total thrust and the total air flow.
The invention generalizes the problem into an optimization problem and establishes a mathematical model shown in formula (2):
Figure BDA0003217980270000082
in the formula, w4、w5、w6Is a target weight coefficient, nlIs the actual speed of the fan, nl,idleIs the slow rotation speed of the fan, far4Is the main combustion chamber gas-oil ratio, far4minIs the lean oil boundary oil-gas ratio of the main combustion chamber, P is the total pressure, PsFor static pressure, backflow margin
Figure BDA0003217980270000091
Subscript "4" represents the main combustion chamber outlet cross-section, subscript "65" represents the mixing chamber outlet cross-section, subscript "C1" represents the ram channel inlet cross-section, and subscript "C2" represents the ram channel outlet cross-section.
The problem is a multi-objective optimization problem, namely, under the conditions that the turbine is in a slow-turning state, the main combustion chamber is not flamed out, and the stamping channel does not flow backwards, the air flow of the turbine channel is reduced as much as possible, the thrust generated by the turbine channel is reduced, and the backflow margin RM as much as possible is obtained.
Figure BDA0003217980270000092
Where the subscripts "C1" and "C2" represent the ram channel inlet and outlet cross-sections, respectively.
The purpose of considering a higher backflow margin is to move the engine away from the backflow boundary, improving the safety of the modal transition below slow.
The optimized mode conversion critical point can be used as a boundary condition, and a basis is provided for the next design research of the mode conversion process control plan.
2.2 design of modality conversion Process control plan:
and taking the optimization result of the mode conversion critical point as the terminal point of forward mode conversion (the turbine engine is in the slow-moving state from the maximum state) and the starting point of reverse mode conversion (the turbine engine is in the slow-moving state from the maximum state), and carrying out research on a mode conversion process control plan.
(1) For a forward mode transition process, the turbine component of the TBCC engine gradually decelerates from a maximum operating state to a slow turning state until a stop (or windmill), and for a reverse mode transition process, the turbine component gradually accelerates from a start-up operation to a slow turning state and from a slow turning state to a maximum operating state, so the mode transition process of the TBCC is an acceleration and deceleration operation process for the turbine component. Unlike conventional turbine engine acceleration and deceleration processes, the mode transition phase, the afterburner/ramjet combustor is still in operation and there is a coupling effect of the turbine component to the ram component. Meanwhile, the working state of the engine is influenced by the variable geometry mechanisms MSV and RVABI, and the smooth transition of the total thrust and the total air flow is required to be ensured in the acceleration and deceleration process.
The part refers to a conventional turbine engine acceleration and deceleration performance optimization method and combines the requirements of a modal conversion process, and introduces a time index reflecting the speed of the conversion process while ensuring the stable transition of thrust and air flow in the modal conversion process, and the time index is defined as the modal conversion time (t)ac). Time t of the mold rotationacCharacterizing the duration of the modal transformation process, which is defined as shown in equation (4):
Figure BDA0003217980270000101
wherein Δ M ═ MT-MC,MTAs turbine torque, MCFor compressor torque, nl,idleIs the slow speed of the fan, nl,maxIs a fanMaximum speed, J, is the rotor moment of inertia.
As can be seen from equation (4), for the forward mode conversion process, in order to reduce the mode conversion time, the absolute value of the residual torque Δ M should be increased as much as possible, that is, the fuel supply to the main combustion chamber is reduced as much as possible, but an excessively small fuel supply may cause a lean blowout of the combustion chamber of the engine, and at the high dead point of the mode conversion, the pressure in the combustion chamber is low, which more easily causes the lean blowout. For the reverse mode conversion process, the main combustor supply should be increased as much as possible, but too high a supply will cause the turbine front temperature to be too high, possibly causing engine surge, over-temperature or rich blowout, as shown in fig. 1.
The critical point of the mode conversion is in a slow-moving state of the turbine, and the turbine component is mainly constrained by the slow-moving speed and the flameout boundary, as shown in formula (5):
Figure BDA0003217980270000102
when the turbine part decelerates, the stamping mode starts, stamping fuel oil is continuously added to increase the thrust, and in the process, the stamping combustion chamber is ensured not to be over-heated and not to exceed the rich oil boundary, and the stamping duct does not generate backflow. The constraint condition of the pressed portion is as shown in equation (6):
Figure BDA0003217980270000103
wherein the subscript "7" is the boost/ramjet combustor exit cross-section, far7For boost/ramjet combustor fuel-to-air ratio, far7maxThe fuel-air ratio of the rich oil boundary of the boosting/stamping combustion chamber is shown, T is the total temperature, T7maxThe total temperature is limited for the afterburner maximum exit.
(2) For the reverse mode conversion process, the turbine component is limited by the maximum turbine front temperature, the main combustion chamber oil-rich boundary line, the surge boundary and the maximum rotating speed, and the constraint conditions are shown as the formula (7):
Figure BDA0003217980270000111
in the formula, nhThe physical rotating speed of the compressor.
In the reverse mode conversion process, the punching press fuel constantly reduces, should guarantee that the punching press combustion chamber does not put out fire this moment, guarantees simultaneously that the punching press duct does not take place the refluence, as shown in formula (8):
Figure BDA0003217980270000112
in the mode conversion process, the stable transition of the engine thrust and the inlet air flow is ensured, the mode conversion time is reduced as far as possible under the condition of meeting the constraint, and the expression of the optimization target is shown as the formula (9):
Figure BDA0003217980270000113
wherein u is a manipulated variable of the engine, and u is [ W ]fb,Wfa,A8,MSV,RVABI]。uminFor minimum value of corresponding regulating variable, umaxIs the maximum value of the corresponding manipulated variable. The subscript "ref" represents the reference value.
By solving the formula (9), the optimal change curve of the engine regulating variable u in the mode conversion process can be obtained, and the controlled quantity (F, W) of each direct performance can be obtaineda1,nl,cor) The optimum variation curve of (2).
TBCC airborne model
For realizing the direct performance control of the engine, the problem that the thrust and the air flow of the engine cannot be directly measured needs to be solved, and in order to solve the problem, the embodiment adopts a BP neural network method to design an airborne model and estimates the true values of the thrust and the air flow in real time. Designing an airborne model, firstly determining input parameters of the model, comparing a TBCC engine with a common turbofan engine, measuring more parameters, if the correlation between the input parameters and the output of the model is not strong,that is, the characteristic information with weak correlation or redundancy will inevitably greatly affect the accuracy of the model and its generalization ability. In essence, the selection of model input parameters is a typical feature selection problem. The invention provides a correlation analysis of the direct energy (thrust and air flow) of an engine and measurable parameters and model input quantity by adopting a Stepwise regression analysis method (SPSS). And screening a group of most valuable parameters as model input by taking the contribution degree of each parameter to the surge margin as a criterion. Firstly, a TBCC engine model is operated to a mode conversion point (H is 12.5km, Ma is 2.1), and during acceleration, deceleration and forward and reverse mode conversion of the engine, state parameters, engine thrust (F) and air flow (W) of the engine can be measureda1) And collecting a sample. All the collected independent variables are 12, and are respectively: p2,T22,P25,T25,P3,T3,P6,T6,Pc1,Pc2,nl,cor,nh,cor. In order to make the sample data of the input variable obey normal distribution or approximately obey normal distribution, the parameter test is convenient to carry out, so the sample data X is subjected to standardized conversion:
Figure BDA0003217980270000121
in the formula (I), the compound is shown in the specification,
Figure BDA0003217980270000122
is the mean of the original sample data input by the model, DX is the variance of X, X*Is the normalized sample data. The same normalization process is also required for the output variable Y. The processed sample data is analyzed by a stepwise regression analysis method, and the absolute value of the check value of each variable T-stat is calculated and obtained as shown in fig. 2 and fig. 3.
The absolute value of the T-stat check value can reflect the importance degree of the corresponding variable to the model. The measurable parameter with greater correlation to F is T22,P25,P3,P6,T6,Pc2,nl,cor,nh,corAnd Wa1The measurable parameter of greater relevance is P2,T22,P25,P3,P6,T6,Pc2,nl,cor,nh,cor. Selecting 8 state parameters with the highest T-stat check value as input parameters of the airborne model, wherein the state parameters are as follows: p2,P25,P3,P6,T6,Pc2,nl,cor,nh,cor(wherein P represents total pressure, T represents total temperature, and subscripts "2", "22", "25", "3" and "6" represent inlet duct outlet, fan outlet, compressor inlet, compressor outlet, and combustion chamber outlet cross-section, respectively).
The engine is generally equivalent to a second-order system, so measurable parameters at the current moment and the previous 2 moments are selected as the input of a neural network, and the engine thrust F (k) at the current moment k and the total air flow W are inputa1(k) As the output of the neural network. Selecting a BP neural network with higher fitting accuracy on a nonlinear object, and constructing an estimation model as shown in formula (11):
P＝fBP(x)
Figure BDA0003217980270000123
4. and (3) establishing a complete control system:
based on the research content, a tandem type TBCC engine modal conversion control device is established, the control structure of which is shown in figure 4, and a PI controller which is commonly used in engineering and has a good effect is adopted as the controller. The pilot sends out a mode switching command and a control command nlcor,ref、Wa1,refAnd FrefControl plan designed according to this patent is given for Wfb、A8And WfaAnd performing closed-loop control. The MSV, RVABI uses open loop regulation, and the regulating instruction is also given by the control plan. Calculating direct performance variable W of engine in real time through BP neural network vehicle-mounted modela1And F, obtaining n through a rotation speed sensorl。
In order to verify the superiority of the method, an isokinetic pressure track (about 55kpa) is selected by taking a tandem type TBCC engine aerodynamic model as an object, H on the track is 12.5, and Ma on the track is 2.1 working points as mode conversion points to carry out simulation verification. The verification is divided into 3 parts: a, neural network estimator verification; optimizing a B mode conversion critical point; and C, simulating the control effect numerical value in the mode conversion process.
A. Neural network estimator validation
The accuracy of airborne model calculation directly affects the effect of direct performance control. And comparing the output of the established airborne model with the output result of the TBCC engine aerodynamic thermodynamic model with higher confidence coefficient.
The percentage of relative error between the onboard model output and the sample output is shown in fig. 5(a), 5 (b). Relative errors of the training points and the test points are less than 0.6%, except for individual points, most sample errors are within 0.2%. The airborne model precision meets the use requirement of a control system.
B. Modal conversion critical point optimization
The mathematical model expression of the modal transformation critical point optimizing design is an optimizing problem with equality constraint and inequality constraint. Because the traditional PSO algorithm is only suitable for solving the unconstrained optimization problem, the mixed penalty function-PSO algorithm (HPPSO) is constructed to solve the problem in a mode of combining the mixed penalty function method and the PSO algorithm.
The optimization problem for general band constraints can be described as:
Figure BDA0003217980270000131
when constructing the mixed penalty function, the inequality constraint constructs the penalty term according to an interior point method, and meanwhile, the equality constraint constructs the penalty term according to an exterior point method. Thus, it can be derived that its augmented objective function is:
Figure BDA0003217980270000132
wherein r is a penalty factor, wherein r(k+1)＝βr(k)(β＝0.05～0.5)。
The critical point optimization method parameter settings are shown in table 2.
TABLE 2 Modal conversion critical point optimization method parameter settings
Figure BDA0003217980270000141
The results before and after optimization are shown in fig. 6 and table 3:
TABLE 3 comparison of optimizing effects at mode transition critical points
Figure BDA0003217980270000142
From the analysis of the above results, it can be seen that the total thrust and the total air flow (W) are maintaineda1) Optimizing the specific gravity (W) of the air in the rear turbine path to the total air mass flow rate with substantially no changea2/Wa1) The thrust generated by the turbine channel accounts for the proportion of the total thrust (F) by 37.14 percentturbo/Ftotal) The reduction is 15.63%. At the same time, the backflow margin RM of the ram duct increases by 73.33%. Optimized main fuel flow (W)fb) Slightly reduced, forced/ram fuel flow (W)fa) Increasing somewhat. At the slow driving point, the turbine state is lower, and the method is more suitable for mode conversion in the state below slow driving.
C. Modal conversion process control effect numerical simulation
The design of the transition state control plan for the mode conversion of the engine above the slow vehicle is only considered, so the optimization result of the section B is used as a forward mode conversion terminal point and a reverse mode conversion starting point in the section, and the optimization research of the transition state control plan in the forward and reverse mode conversion process is developed. A mixed penalty function-particle swarm optimization algorithm is also adopted, and the parameters of the optimization algorithm are shown in table 4:
TABLE 4 Modal conversion Process optimization method parameter settings
Figure BDA0003217980270000151
The optimization results of the forward and reverse mode conversion processes are shown in fig. 7(a) to 7(h) and fig. 8(a) to 8(h), respectively.
The following conclusions are drawn from the simulation result analysis:
(1) in the process of converting the forward mode and the reverse mode, the stable transition of the thrust and the total air flow can be realized. When the reverse mode conversion is carried out to the 12 th s, the reverse mode conversion is influenced by the closing of the stamping duct, 0.14% of thrust fluctuation and 1.83% of total air flow fluctuation are generated, besides, the fluctuation of the thrust is not more than 0.07%, and the fluctuation of the total air flow is not more than 1.53%, so that the condition that an air inlet adjustable mechanism is not required to be additionally adjusted in the mode conversion process is basically met.
(2) In the whole process, the surge margin of the fan and the compressor is more than 0.2, the residual gas coefficient of the main combustion chamber and the boosting/stamping combustion chamber does not exceed the lean oil/rich oil boundary, and the total outlet temperature does not exceed the maximum allowable temperature. In the whole process, the backflow margin of the stamping duct is larger than 0.1, and the safety margin is high.
(3) Compared with simulation results in documents [ M.Zhang, Z.Wang, Z.Liu, X.Zhang, Analysis of mode transfer performance for a distance TBCC engine, in:52nd AIAA/SAE/ASEE Joint prediction Conference, 2016.https:// doi.org/10.2514/6.2016-4573 ], the speed of mode conversion is improved by over 75 percent.
In order to further verify the feasibility of the direct performance transition state control plan, a system closed loop simulation circuit is set up. In order to make the simulation result closer to reality, a PI controller which is frequently used in engineering is adopted.
The control effect of the forward mode conversion is shown in fig. 9(a) to 9(c), and the control effect of the reverse mode conversion is shown in fig. 10(a) to 10 (c).
From the closed-loop control effect, the maximum thrust fluctuation is 0.74%, the maximum air flow fluctuation is 5.25%, and the mode conversion time is limited within 20s, so that the thrust fluctuation is reduced by 2.76% compared with the result in the document [ X ]. The air flow fluctuation was reduced by 1.75%. The result shows that the design of the closed-loop control system by adopting the invention can meet the requirements of safe, stable and fast transition during the conversion period.

Claims (10)

1. A tandem type TBCC engine modal conversion control method is characterized in that in the engine modal conversion process, the maximum state working point and the slow vehicle state working point of a turbine component are used as optimization boundaries, and the total thrust F and the total air flow W in the modal conversion process are obtained through optimization solutiona1Fan conversion speed nl,corThe opening RVABI of the rear variable-area bypass ejector and the opening MSV of the mode conversion valve are optimized according to the change curves, and then the total thrust F and the total air flow W are useda1Fan conversion speed nl,corThe three optimal change curves of the direct energy perform closed-loop control on the engine, and then the optimal change curves of the variable-area bypass ejector opening RVABI and the mode conversion valve opening MSV perform open-loop control on the engine; the optimization solution is specifically to solve the following first optimization model:
Figure FDA0003217980260000011
s.t.umin≤u≤umax
Figure FDA0003217980260000012
Figure FDA0003217980260000013
where u is the engine control variable and u is [ W ]fb,Wfa,A8,MSV,RVABI]，WfbFor the main fuel flow of the turbine combustion chamber, A8Is the area of the throat of the exhaust nozzle, WfaRVABI is the opening of a rear variable-area duct injector and MSV is the die for boosting/stamping fuel flowFormula switching valve opening degree, SmlFor fan surge margin, SmhFor the compressor surge margin, the subscripts "min" and "max" represent the minimum value and the maximum value, respectively, the subscript "ref" represents the command value, w1、w2、w3Is a target weight coefficient, tacIs defined as the time of the mode rotation,
Figure FDA0003217980260000014
ΔM＝MT-MC，MTas turbine torque, MCFor compressor torque, nhIs the physical speed of the compressor, nlIs the actual speed of the fan, nl,idleIs the slow speed of the fan, nl,maxThe maximum rotation speed of the fan, J is the rotational inertia of the rotor, P is the total pressure, and P issFor static pressure, far is the air-fuel ratio, T is the total temperature, subscript "4" represents the main combustion chamber exit cross-section, subscript "65" represents the mixing chamber exit cross-section, subscript "7" represents the boost/ram combustion chamber exit cross-section, and subscript "C1" represents the ram channel inlet cross-section.
2. The tandem TBCC engine modal conversion control method of claim 1 wherein the turbine component slow regime operating point as the optimization boundary is obtained by solving a second optimization model of:
minJ＝w4×F+w5×Wa2+w6×RM
Figure FDA0003217980260000021
in the formula, w4、w5、w6Is a target weight coefficient, nlIs the actual speed of the fan, nl,idleIs the slow rotation speed of the fan, far4Is the main combustion chamber gas-oil ratio, far4minIs the lean oil boundary oil-gas ratio of the main combustion chamber, P is the total pressure, PsFor static pressure, backflow margin
Figure FDA0003217980260000022
Subscript "4" represents the main combustion chamber outlet cross-section, subscript "65" represents the mixing chamber outlet cross-section, subscript "C1" represents the ram channel inlet cross-section, and subscript "C2" represents the ram channel outlet cross-section.
3. The tandem TBCC engine modal conversion control method of claim 2 wherein said second optimization model is solved using a hybrid penalty function method in combination with a particle swarm optimization algorithm.
4. The tandem TBCC engine mode transition control method of claim 1 wherein said total thrust F and total air flow Wa1Measurable parameters are used as input and are estimated through an airborne model based on a neural network; the inputs to the onboard model are selected using stepwise regression analysis with total thrust F and total air flow Wa1The most relevant set of measurable parameters.
5. The tandem TBCC engine mode transition control method of claim 4 wherein said onboard model is specified as follows:
P＝fBP(x)
Figure FDA0003217980260000023
wherein P represents total pressure, T represents total temperature, nl,corConversion of the speed of rotation of the fan, nh,corFor the converted rotating speed of the compressor, subscripts of 2, 22, 25, 3 and 6 respectively represent the sections of an air inlet channel outlet, a fan outlet, a compressor inlet, a compressor outlet and a combustion chamber outlet, subscript BP represents a BP neural network, and k-1 and k-2 respectively represent the first 1 moment and the first 2 moment of the current k moment.
6. A tandem TBCC engine mode transition control device comprising:
the mode conversion control plan module is used for obtaining total thrust F and total air flow W in the mode conversion process by taking the maximum state working point and the slow turning state working point of the turbine component as optimization boundaries through optimization solution in the engine mode conversion processa1Fan conversion speed nl,corThe opening degree RVABI of the variable-area bypass ejector and the opening degree MSV of the mode conversion valve are subjected to open-loop control; the optimization solution is specifically to solve the following first optimization model:
Figure FDA0003217980260000031
s.t.umin≤u≤umax
Figure FDA0003217980260000032
Figure FDA0003217980260000033
where u is the engine control variable and u is [ W ]fb,Wfa,A8,MSV,RVABI]，WfbFor the main fuel flow of the turbine combustion chamber, A8Is the area of the throat of the exhaust nozzle, WfaRVABI is the opening degree of the rear variable-area bypass ejector and MSV is the opening degree of the mode switching valve for boosting/stamping fuel flowmlFor fan surge margin, SmhFor the compressor surge margin, the subscripts "min" and "max" represent the minimum value and the maximum value, respectively, the subscript "ref" represents the command value, w1、w2、w3Is a target weight coefficient, modulo rotation time
Figure FDA0003217980260000041
ΔM＝MT-MC，MTAs turbine torque, MCFor compressor torque, nhIs the physical speed of the compressor, nlIs the actual speed of the fan, nl,idleIs the slow speed of the fan, nl,maxThe maximum rotation speed of the fan, J is the rotational inertia of the rotor, P is the total pressure, and P issFor static pressure, far is the oil-gas ratio, T is the total temperature, subscript "4" represents the main combustion chamber outlet cross-section, subscript "65" represents the mixing chamber outlet cross-section, subscript "7" represents the boost/ram combustion chamber outlet cross-section, subscript "C1" represents the ram channel inlet cross-section;
engine controller for controlling total thrust F and total air flow Wa1Fan conversion speed nl,corThe three optimal change curves of the direct energy perform closed-loop control on the engine.
7. The tandem TBCC engine modal conversion control apparatus of claim 6 wherein the turbine component slow regime operating point as the optimization boundary is obtained by solving a second optimization model of:
minJ＝w4×F+w5×Wa2+w6×RM
Figure FDA0003217980260000042
in the formula, w4、w5、w6Is a target weight coefficient, nlIs the actual speed of the fan, nl,idleIs the slow rotation speed of the fan, far4Is the main combustion chamber gas-oil ratio, far4minIs the lean oil boundary oil-gas ratio of the main combustion chamber, P is the total pressure, PsFor static pressure, backflow margin
Figure FDA0003217980260000043
Subscript "4" represents the main combustion chamber outlet cross-section, subscript "65" represents the mixing chamber outlet cross-section, subscript "C1" represents the ram channel inlet cross-section, and subscript "C2" represents the ram channel outlet cross-section.
8. The tandem TBCC engine modal conversion control apparatus of claim 7 wherein said second optimization model is solved using a hybrid penalty function method in combination with a particle swarm optimization algorithm.
9. The tandem TBCC engine mode transition control apparatus of claim 6 wherein said total thrust F and total air flow Wa1Measurable parameters are used as input and are estimated through an airborne model based on a neural network; the inputs to the onboard model are selected using stepwise regression analysis with total thrust F and total air flow Wa1The most relevant set of measurable parameters.
10. The tandem TBCC engine mode transition control apparatus of claim 9 wherein said onboard model is specified as follows:
P＝fBP(x)
Figure FDA0003217980260000051
wherein P represents total pressure, T represents total temperature, nl,corConversion of the speed of rotation of the fan, nh,corFor the converted rotating speed of the compressor, subscripts of 2, 22, 25, 3 and 6 respectively represent the sections of an air inlet channel outlet, a fan outlet, a compressor inlet, a compressor outlet and a combustion chamber outlet, subscript BP represents a BP neural network, and k-1 and k-2 respectively represent the first 1 moment and the first 2 moment of the current k moment.
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