The reignition of aero-engine combustors at high altitudes poses significant challenges due to the low-temperature and low-pressure environment.A novel Long Pulse-Width Plasma Ignition(LPWPI)system has been developed ...The reignition of aero-engine combustors at high altitudes poses significant challenges due to the low-temperature and low-pressure environment.A novel Long Pulse-Width Plasma Ignition(LPWPI)system has been developed to enhance ignition performance.The LPWPI system can effectively prolong the discharge duration time,improve ignition efficacy,and increase the plasma penetration depth.Experimental comparisons with the traditional Spark Ignition(SI)system demonstrate that the LPWPI increased discharge duration to 2.03 ms,which is 45 times longer than that of the SI system,while also doubling the spark penetration depth to 24.1 mm.The LPWPI system achieved a discharge efficiency of 61.1%,significantly surpassing the SI system's efficiency of23.3%.These advancements facilitated an extension of the lean ignition boundary by approximately 22.7%to 39.3%.High-speed camera recordings reveal that the spark duration of the LPWPI system was extended to 2.1 ms,compared to 0.6 ms in the SI system.Ignition progress with LPWPI shows a sustained spark kernel without the flame residence stage observed in the SI system.The impressive performance of the LPWPI system suggests that it is a promising alternative for aero-engine ignition systems.展开更多
In order to solve the aero-propulsion system acceleration optimal problem,the necessity of inlet control is discussed,and a fully new aero-propulsion system acceleration process control design including the inlet,engi...In order to solve the aero-propulsion system acceleration optimal problem,the necessity of inlet control is discussed,and a fully new aero-propulsion system acceleration process control design including the inlet,engine,and nozzle is proposed in this paper.In the proposed propulsion system control scheme,the inlet,engine,and nozzle are simultaneously adjusted through the FSQP method.In order to implement the control scheme design,an aero-propulsion system componentlevel model is built to simulate the inlet working performance and the matching problems between the inlet and engine.Meanwhile,a stabilizing inlet control scheme is designed to solve the inlet control problems.In optimal control of the aero-propulsion system acceleration process,the inlet is an emphasized control unit in the optimal acceleration control system.Two inlet control patterns are discussed in the simulation.The simulation results prove that by taking the inlet ramp angle as an active control variable instead of being modulated passively,acceleration performance could be obviously enhanced.Acceleration objectives could be obtained with a faster acceleration time by5%.展开更多
In this paper, ballistic impact tests on wrapped multi-layer Kevlar 49 woven fabric systems were carried out with a flat blade projectile to investigate the impact response during a fan blade out event. The influences...In this paper, ballistic impact tests on wrapped multi-layer Kevlar 49 woven fabric systems were carried out with a flat blade projectile to investigate the impact response during a fan blade out event. The influences of the number of Kevlar layers and pre-tension were discussed particularly. Test results were used to analyze failure modes and energy absorption characteristics of multi-ply Kevlar fabrics. Results show that there are two kinds of impact damage for fabrics： global deformation mainly involving stretching of yarns in the impact region and fabric wrinkle from both sides to the impact zone, and local damage characterized by yarn fracture, yarn pull-out, and yarn unraveling. The energy absorption capability of Kevlar 49 woven fabrics improves with the number of fabric layers. The energy absorbed by multi-layer fabrics increases slightly at the beginning and then decreases substantially with pre-tension. The work in this paper can provide guidance for designing light-weight multi-layer fabrics containment systems.展开更多
The submerged inlet is an attractive configuration for advanced helicopters due to its high stealth performance and low external drag.In this paper,a submerged inlet,integrated with a ROBIN helicopter fuselage and a s...The submerged inlet is an attractive configuration for advanced helicopters due to its high stealth performance and low external drag.In this paper,a submerged inlet,integrated with a ROBIN helicopter fuselage and a simplified power output shaft,is experimentally and numerically investigated to obtain the basic flow characteristics under a freestream velocity of 23.6 m/s.The results indicate that the pylon ahead of the inlet induces a horseshoe vortex.Though the vortex is ingested into the inlet,it has little effect on the internal flows and can be neglected.When the airflow enters into the inlet,it interacts with the shaft with a large incidence angle,yielding a vortex pair.At the leeside of the shaft,the two side flows of the shaft impinge at the center plane,generating a local high-pressure region at the azimuthal angle of 180°,which forces the boundary layer to roll up a counter-rotating vortex pair.In addition,the airflow adjacent to the cowl lip accelerates rapidly,resulting in a local low-pressure region at the azimuthal angle of 0°.Therefore,the inlet duct has a strong circumferential pressure gradient,which originates from an azimuthal angle of 180°to 0°and induces a vortex pair at the azimuthal angle of 0°.The three vortex pairs are the main origins of the distortion at the duct exit plane,among which the one near the cowl lip with the azimuthal angle of 0°plays the dominant role.Additionally,as the velocity ratio increases from 3.9 to 5.5,the circumferential pressure gradient and the cowl lip vortex get intensified,which causes that the total-pressure recovery coefficient drops by 0.5%and the distortion index increases by 28%.展开更多
This paper addresses the gas path component and sensor fault diagnosis and isolation(FDI) for the auxiliary power unit(APU). A nonlinear dynamic model and a distributed state estimator are combined for the distributed...This paper addresses the gas path component and sensor fault diagnosis and isolation(FDI) for the auxiliary power unit(APU). A nonlinear dynamic model and a distributed state estimator are combined for the distributed control system. The distributed extended Kalman filter(DEKF)is served as a state estimator,which is utilized to estimate the gas path components’ flow capacity. The DEKF includes one main filter and five sub-filter groups related to five sensors of APU and each sub-filter yields local state flow capacity. The main filter collects and fuses the local state information,and then the state estimations are feedback to the sub-filters. The packet loss model is introduced in the DEKF algorithm in the APU distributed control architecture. FDI strategy with a performance index named weight sum of squared residuals(WSSR) is designed and used to identify the APU sensor fault by removing one sub-filter each time. The very sensor fault occurs as its performance index WSSR is different from the remaining sub-filter combinations. And the estimated value of the soft redundancy replaces the fault sensor measurement to isolate the fault measurement. It is worth noting that the proposed approach serves for not only the sensor failure but also the hybrid fault issue of APU gas path components and sensors. The simulation and comparison are systematically carried out by using the APU test data,and the superiority of the proposed methodology is verified.展开更多
Cowl-induced incident Shock Wave/Boundary Layer Interactions (SWBLI) under the influence of gradual expansion waves are frequently observed in supersonic inlets. However, the analysis and prediction of interaction len...Cowl-induced incident Shock Wave/Boundary Layer Interactions (SWBLI) under the influence of gradual expansion waves are frequently observed in supersonic inlets. However, the analysis and prediction of interaction lengths have not been sufficiently investigated. First, this study presents a theoretical scaling analysis and validates it through wind tunnel experiments. It conducts detailed control volume analysis of mass conservation, considering the differences between inviscid and viscous cases. Then, three models for analysing interaction length under gradual expansion waves are derived. Related experiments using schlieren photography are conducted to validate the models in a Mach 2.73 flow. The interaction scales are captured at various relative distances between the shock impingement location and the expansion regions with wedge angles ranging from 12° to 15° and expansion angles of 9°, 12°, and 15°. Three trend lines are plotted based on different expansion angles to depict the relationship between normalised interaction length and normalised interaction strength metric. In addition, the relationship between the coefficients of the trend line and the expansion angles is introduced to predict the interaction length influenced by gradual expansion waves. Finally, the estimation of normalised interaction length is derived for various coefficients within a unified form.展开更多
Variable Cycle Engine(VCE)serves as the core system in achieving future advanced fighters with cross-generational performance and mission versatility.However,the resultant complex configuration and strong coupling of ...Variable Cycle Engine(VCE)serves as the core system in achieving future advanced fighters with cross-generational performance and mission versatility.However,the resultant complex configuration and strong coupling of control parameters present significant challenges in designing acceleration and deceleration control schedules.To thoroughly explore the performance potential of engine,a global integration design method for acceleration and deceleration control schedule based on inner and outer loop optimization is proposed.The outer loop optimization module employs Integrated Surrogate-Assisted Co-Differential Evolutionary(ISACDE)algorithm to optimize the variable geometry adjustment laws based on B-spline curve,and the inner loop optimization module adopts the fixed-state method to design the open-loop fuel–air ratio control schedules,which are aimed at minimizing the acceleration and deceleration time under multiple constraints.Simulation results demonstrate that the proposed global integration design method not only furthest shortens the acceleration and deceleration time,but also effectively safeguards the engine from overlimit.展开更多
The development of the adaptive cycle engine is a crucial direction of advanced fighter power sources in the near future.However,this new technology brings more uncertainty to the design of the control system.To addre...The development of the adaptive cycle engine is a crucial direction of advanced fighter power sources in the near future.However,this new technology brings more uncertainty to the design of the control system.To address the versatile thrust demand under complex dynamic characteristics of the adaptive cycle engine,this paper proposes a direct thrust estimation and control method based on the Model-Free Adaptive Control(MFAC)algorithm.First,an improved Sliding Mode Control-MFAC(SMC-MFAC)algorithm has been developed by introducing a sliding mode variable structure into the standard Full Format Dynamic Linearization-MFAC(FFDL-MFAC)and designing self-adaptive weight coefficients.Then a trivariate double-loop direct thrust control structure with a controller-based thrust estimator and an outer command compensation loop has been established.Through thrust feedback and command correction,accurate control under multi-mode and operation conditions is achieved.The main contribution of this paper is the improved algorithm that combines the tracking capability of the MFAC and the robustness of the SMC,thus enhancing the dynamic performance.Considering the requirements of the online thrust feedback,the designed MFAC-based thrust estimator significantly speeds up the calculation.Additionally,the proposed command correction module can achieve the adaptive thrust control without affecting the operation of the inner loop.Simulations and Hardware-in-Loop(HIL)experiments have been performed on an adaptive cycle engine component-level model to investigate the estimation and control effect under different modes and health conditions.The results demonstrate that both the thrust estimation precision and operation speed are significantly improved compared with Extended Kalman Filter(EKF).Furthermore,the system can accelerate the response of the controlled plant,reduce the overshoot,and realize the thrust recovery within the safety range when the engine encounters the degradation.展开更多
In order to realize the automatic recognition and classification of cracks with different depths,in this study,several deep convolutional neural networks including AlexNet,ResNet,and DenseNet were employed to identify...In order to realize the automatic recognition and classification of cracks with different depths,in this study,several deep convolutional neural networks including AlexNet,ResNet,and DenseNet were employed to identify and classify cracks at different depths and in various materials.An analysis process for the automatic classification of crack damage was presented.The image dataset used for model training was obtained from scanning experiments on aluminum and titanium alloy plates using an ultrasonic phased-array flaw detector.All models were trained and validated with the dataset;the proposed models were compared using classification precision and loss values.The results show that the automatic recognition and classification of crack depth can be realized by using the deep learning algorithm to analyze the ultrasonic phased array images,and the classification precision of DenseNet is the highest.The problem that ultrasonic damage identification relies on manual experience is solved.展开更多
Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore it...Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore its creep properties.In this work,a series of RHT experiments were carried out on a directionally solidified(DS)nickel-based superalloy under different solution temperatures and primary aging temperatures based on the standard heat treatment(SHT)process parameters to investigate the mechanism of temperature influence on DS's microstructure after RHT.It is indicated that a more uniform microstructure can be obtained under higher solution temperatures and lower primary aging temperatures compared to the SHT process.Furthermore,by employing the image processing methods to quantify microstructural parameters,a comprehensive indicator parameter for the RHT effect(marked as Prej)was proposed to characterize the effects of RHT on DS superalloy's microstructure and creep property combined with the entropy weight method.Based on this,a regression model to describe the relationship between RHT process parameters and Prej was constructed by using the response surface methodology(RSM).It is revealed that the optimal solution temperature and primary aging temperature for this DS superalloy are 1283°C and 1095°C,respectively.Then the conclusion was validated through complete creep experiments on the DS superalloy,which showed the creep life after RHT reaches 95.5%of the SHT specimen,and the total life has increased by 20.6%.展开更多
The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Pl...The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Plasticized Polyether(NEPE) propellant/Hydroxyl-terminated Polybutadiene(HTPB) liner/Ethylene Propylene Diene Monomer(EPDM) insulation bonding system. This paper proposes an innovative surface modification method attempting to modify the EPDM insulation layer coated with reduced graphene oxide(RGO), which exhibits ability to weaken the NG absorption by EPDM insulation layer,blocking the pathway of NG migration into EPDM insulation materials. The microstructure of RGO-coated layer was analyzed and the formation mechanism was investigated. The RGO-coated layer is well bonded to the HTPB liner, and its anti-migration performance to NG at different temperatures has been evaluated. Comparing with blank samples under the same storage conditions, the RGO-coated layers can reduce the diffusion coefficient of NG by up to 87.3% and increase the diffusion activation energy of NG by14.8 kJ,mol^(-1). This research provides a new strategy to effectively inhibit NG migration in NEPE propellant/HTPB liner/EPDM insulation bonding system.展开更多
The advancement of functional adhesives featuring recyclable and repairable properties is of great significance in interfacial science and engineering.Herein,a series of high-strength,recyclable fluorine-containing ad...The advancement of functional adhesives featuring recyclable and repairable properties is of great significance in interfacial science and engineering.Herein,a series of high-strength,recyclable fluorine-containing adhesives(ESOx-FPF)were designed and synthesized by crosslinking two prepolymers,FPF-B(derived from side-chain fluorinated diol,isocyanate,and aminoboric acid)and ESO-B(synthesized from biobased epoxy soybean oil and aminoboric acid),through dynamic boro-oxygen bonds.The resulting adhesive exhibited an optimal tensile strength of 42 MPa and the shear strength on steel plates reached as high as 3.89 MPa.More importantly,benefiting from the dynamic reversibility of the boron-oxygen bonds along with the hydrogen bonds interaction,ESOx-FPF can be welded with the assistance of solvents and recycled for multiple cycles.The outstanding healing efficiency and excellent reprocessability of these functional adhesives were confirmed by mechanical testing.Moreover,the as-prepared adhesives demonstrated universal and remarkable adhesion to various substrates,such as aromatic polyamide,aluminum plates and polycarbonate,meanwhile,they could be easily disassembled and recycled using ethanol without damaging the substrates surface.This study not only provides a simple strategy for the synthesis of eco-friendly adhesives with weldable and recyclable properties,but also sheds light on the development of other functional materials utilizing dynamic covalent chemistry.展开更多
Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local...Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local resonance can effectively balance the volume occupation and low-frequency absorption performance.However,these materials often exhibit a very narrow and fixed absorption band.Inspired by Helmholtz resonators and bistable structures,we propose bistable reconfigurable acoustic metamaterials(BRAMs)that offer multiband low-frequency absorption.These BRAMs are fabricated using shape-memory polylactic acid(SM-PLA)via four-dimension(4D)printing technology.Consequently,the geometry and absorption performance of the BRAMs can be adjusted by applying thermal stimuli(at 55℃)to switch between two stable states.The BRAMs demonstrate excellent low-frequency absorption with multiband characteristics,achieving an absorption coefficient of 0.981 at 136 Hz and 0.998 at 230 Hz for stable state I,and coefficients of 0.984 at 156 Hz and 0.961 at 542 Hz for stable state II.It was found that the BRAMs with different inclined plate angles had linear recovery stages,and the recovery speeds range from 0.75 mm/s to 1.1 mm/s.By combining a rational structural design and 4D printing,the reported reconfigurable acoustic metamaterials will inspire further studies on the design of dynamic and broadband absorption devices.展开更多
Aero-engine gas path health monitoring plays a critical role in Engine Health Management(EHM). To achieve unbiased estimation, traditional filtering methods have strict requirements on measurement parameters which som...Aero-engine gas path health monitoring plays a critical role in Engine Health Management(EHM). To achieve unbiased estimation, traditional filtering methods have strict requirements on measurement parameters which sometimes cannot be measured in engineering. The most typical one is the High-Pressure Turbine(HPT) exit pressure, which is vital to distinguishing failure modes between different turbines. For the case of an abrupt failure occurring in a single turbine component, a model-based sensor measurement reconstruction method is proposed in this paper. First,to estimate the missing measurements, the forward algorithm and the backward algorithm are developed based on corresponding component models according to the failure hypotheses. Then,a new fault diagnosis logic is designed and the traditional nonlinear filter is improved by adding the measurement estimation module and the health parameter correction module, which uses the reconstructed measurement to complete the health parameters estimation. Simulation results show that the proposed method can well restore the desired measurement and the estimated measurement can be used in the turbofan engine gas path diagnosis. Compared with the diagnosis under the condition of missing sensors, this method can distinguish between different failure modes, quantify the variations of health parameters, and achieve good performance at multiple operating points in the flight envelope.展开更多
An experimental study is made to investigate the film cooling performance of imperfect holes due to in-hole blockage over a flat plate. A specifically pyramid-shaped element is used to simulate the in-hole blockage. S...An experimental study is made to investigate the film cooling performance of imperfect holes due to in-hole blockage over a flat plate. A specifically pyramid-shaped element is used to simulate the in-hole blockage. Six in-hole blockage orientations（such as leading-inlet, leading-middle,leading-exit, trailing-inlet, trailing-middle and trailing-exit） and four blocking ratios（ranging from 0.1 to 0.4） are taken into considerations. Based on the experimental results, the influences of in-hole blockage on the film cooling effectiveness and discharge coefficient under typical blowing ratios are analyzed. It is confirmed that the in-hole blockage results in a reduction of discharge coefficient related to the perfect film cooling holes, especially for the leading-exit and trailing-inlet orientations with a big blocking ratio. However, in the view of film cooling effectiveness, the in-hole blockage shows complicated affecting roles. In general, except for the leading-exit orientation, the in-hole blockages produce detrimental influence on the film cooling effectiveness.展开更多
To address the curvature effect on single-row chevron-nozzle jet impingement heat transfer on concave surface,a series of experiments are conducted in the present investigation.Four concave surfaces including one semi...To address the curvature effect on single-row chevron-nozzle jet impingement heat transfer on concave surface,a series of experiments are conducted in the present investigation.Four concave surfaces including one semi-cylindrical concave surface and three parabolic concave surfaces with different width-to-depth ratios are tested under three typical Reynolds numbers(Re=5000,10000 and 15000)and several dimensionless nozzle-to-surface distances ranging from 1 to 8.The results show that the concave curvature has a clear impact on chevron-nozzle jet impingement heat transfer,tightly dependent on jet Reynolds number and impinging distance.In general,the semicylindrical concave surface produces the highest longitudinally-averaged Nusselt number at the leading line of concave surface.Under a low jet Reynolds number,the parabolic concave surface with a highly curved curvature produces higher longitudinally-averaged Nusselt number at the leading line and more uniform longitudinally-averaged Nusselt number distribution along the curvilinear direction.However,the longitudinally-averaged Nusselt number at the leading line of concave surface is the lowest for the highly curved surface under a high jet Reynolds number and large impinging distance.In comparison with the round-nozzle,chevron nozzle plays a more significant role on improving jet impingement heat transfer at small impinging distances.展开更多
In order to analyze the stress and strain fields in the fibers and the matrix in composite materials,a fiber-scale unit cell model is established and the corresponding periodical boundary conditions are introduced.Ass...In order to analyze the stress and strain fields in the fibers and the matrix in composite materials,a fiber-scale unit cell model is established and the corresponding periodical boundary conditions are introduced.Assuming matrix cracking as the failure mode of composite materials,an energy-based fatigue damage parameter and a multiaxial fatigue life prediction method are established.This method only needs the material properties of the fibers and the matrix to be known.After the relationship between the fatigue damage parameter and the fatigue life under any arbitrary test condition is established,the multiaxial fatigue life under any other load condition can be predicted.The proposed method has been verified using two different kinds of load forms.One is unidirectional laminates subjected to cyclic off-axis loading,and the other is filament wound composites subjected to cyclic tension-torsion loading.The fatigue lives predicted using the proposed model are in good agreements with the experimental results for both kinds of load forms.展开更多
A nonlinear model predictive control method based on fuzzy-Sequential Quadratic Programming(SQP)for direct thrust control is proposed in this paper for the sake of improving the accuracy of thrust control.The designed...A nonlinear model predictive control method based on fuzzy-Sequential Quadratic Programming(SQP)for direct thrust control is proposed in this paper for the sake of improving the accuracy of thrust control.The designed control system includes four parts,namely a predictive model,rolling optimization,online correction,and feedback correction.Considering the strong nonlinearity of engine,a predictive model is established by Back Propagation(BP)neural network for the entire flight envelope,whose input and output are determined with random forest algorithm and actual situation analysis.Rolling optimization typically uses SQP as the optimization algorithm,but SQP algorithm is easy to trap into local optimization.Therefore,the fuzzy-SQP algorithm is proposed to prevent this disadvantage using fuzzy algorithm to determine the initial value of SQP.In addition to the traditional three parts of model predictive control,an online correction module is added to improve the predictive accuracy of the predictive model in the predictive time domain.Simulation results show that the BP predictive model can reach a certain degree of predictive accuracy,and the proposed control system can achieve good tracking performance with the limited parameters within the safe range。展开更多
Bypass Dual Throat Nozzle(BDTN)is a novel type of fluidic thrust vectoring nozzle.To improve the infrared stealth performance of BDTN,a nozzle based on BDTN is proposed and numerically simulated.Each cross-section alo...Bypass Dual Throat Nozzle(BDTN)is a novel type of fluidic thrust vectoring nozzle.To improve the infrared stealth performance of BDTN,a nozzle based on BDTN is proposed and numerically simulated.Each cross-section along the x-axis of the novel nozzle becomes a trapezoid,which is named“BDTN-TRA.”The main numerical simulation results show that BDTN-TRA can produce a thrust vectoring angle when the upper or lower bypass valve is open.The angle difference between the two conditions mentioned above is usually approximately 1°-2°.Even if the two bypasses are closed,BDTN-TRA can produce a small thrust vectoring angle at around 3°-5°.When the sidewall angle increases from 60°to 90°,the thrust coefficient and thrust vectoring angle under each work condition usually decrease.A larger aspect ratio indicates better performance.As the aspect ratio increases over 7.2,the performance of BDTN-TRA is quite close to that of BDTN with rectangular cross-sections at the same aspect ratio.These features will benefit the control and trimming for future aircraft design,especially for the flying wing layout aircraft.Last but not least,BDTN-TRA has a more extraordinary mixing performance compared with BDTN.The distributions of static temperature and axial velocity along the x-axis of BDTN-TRA with sidewall angle of 60°decrease faster than those of BDTN.When the total temperature of the inlet equals 1600 K,the static temperature difference between BDTN-TRA with sidewall angles of 60°and 90°is over 360 K at twice the length of the nozzle downstream of the nozzle exit,which is the reflection for excellent infrared stealth for the fighter.展开更多
A novel turbofan Direct Thrust Control(DTC)architecture based on Linear ParameterVarying(LPV)approach for a two-spool turbofan engine thrust control is proposed in this paper.Instead of transforming thrust command to ...A novel turbofan Direct Thrust Control(DTC)architecture based on Linear ParameterVarying(LPV)approach for a two-spool turbofan engine thrust control is proposed in this paper.Instead of transforming thrust command to shaft speed command and pressure ratio command,the thrust will be directly controlled by an optimal controller with two control variables.LPV model of the engine is established for the designing of thrust estimator and controller.A robust LPV H∞filter is introduced to estimate the unmeasurable thrust according to measurable engine states.The thrust estimation error system is proved to be Affinely Quadratically Stable(AQS)in the whole parameter box with a prescribed H∞performance indexγ.Due to the existence of overdetermined equations,the solving of controller parameters is a multi-solution problem.Therefore,Particle Swarm Optimization(PSO)algorithm is used to optimize the controller parameters to obtain satisfactory control performance based on the engine’s LPV model.Numerical simulations show that the thrust estimator can acquire smooth and accurate estimating results when sensor noise exists.The optimal controller can receive desired control performance both in steady and transition control tasks within the engine working states above the idle,verifying the effectiveness of the proposed DTC architecture’s application in thrust direct control problem.展开更多
基金co-supported by the National Natural Science Foundation of China(Nos.52376138 and 52025064)the Science Center for Gas Turbine Project,China(No.P2022B-Ⅱ-018-001)the Foundation Research Project,China(No.1002TJA22010)。
文摘The reignition of aero-engine combustors at high altitudes poses significant challenges due to the low-temperature and low-pressure environment.A novel Long Pulse-Width Plasma Ignition(LPWPI)system has been developed to enhance ignition performance.The LPWPI system can effectively prolong the discharge duration time,improve ignition efficacy,and increase the plasma penetration depth.Experimental comparisons with the traditional Spark Ignition(SI)system demonstrate that the LPWPI increased discharge duration to 2.03 ms,which is 45 times longer than that of the SI system,while also doubling the spark penetration depth to 24.1 mm.The LPWPI system achieved a discharge efficiency of 61.1%,significantly surpassing the SI system's efficiency of23.3%.These advancements facilitated an extension of the lean ignition boundary by approximately 22.7%to 39.3%.High-speed camera recordings reveal that the spark duration of the LPWPI system was extended to 2.1 ms,compared to 0.6 ms in the SI system.Ignition progress with LPWPI shows a sustained spark kernel without the flame residence stage observed in the SI system.The impressive performance of the LPWPI system suggests that it is a promising alternative for aero-engine ignition systems.
基金co-supported by the Fundamental Research Funds for the Central Universities(No:NZ2016103)the National Natural Science Foundation of China(No: 51576096)
文摘In order to solve the aero-propulsion system acceleration optimal problem,the necessity of inlet control is discussed,and a fully new aero-propulsion system acceleration process control design including the inlet,engine,and nozzle is proposed in this paper.In the proposed propulsion system control scheme,the inlet,engine,and nozzle are simultaneously adjusted through the FSQP method.In order to implement the control scheme design,an aero-propulsion system componentlevel model is built to simulate the inlet working performance and the matching problems between the inlet and engine.Meanwhile,a stabilizing inlet control scheme is designed to solve the inlet control problems.In optimal control of the aero-propulsion system acceleration process,the inlet is an emphasized control unit in the optimal acceleration control system.Two inlet control patterns are discussed in the simulation.The simulation results prove that by taking the inlet ramp angle as an active control variable instead of being modulated passively,acceleration performance could be obviously enhanced.Acceleration objectives could be obtained with a faster acceleration time by5%.
基金co-supported by the National Natural Science Foundation of China (No.51575262)the China Postdoctoral Science Foundation (No.2015M571754)the Aeronautical Science Foundation of China (No.2015ZB52008)
文摘In this paper, ballistic impact tests on wrapped multi-layer Kevlar 49 woven fabric systems were carried out with a flat blade projectile to investigate the impact response during a fan blade out event. The influences of the number of Kevlar layers and pre-tension were discussed particularly. Test results were used to analyze failure modes and energy absorption characteristics of multi-ply Kevlar fabrics. Results show that there are two kinds of impact damage for fabrics： global deformation mainly involving stretching of yarns in the impact region and fabric wrinkle from both sides to the impact zone, and local damage characterized by yarn fracture, yarn pull-out, and yarn unraveling. The energy absorption capability of Kevlar 49 woven fabrics improves with the number of fabric layers. The energy absorbed by multi-layer fabrics increases slightly at the beginning and then decreases substantially with pre-tension. The work in this paper can provide guidance for designing light-weight multi-layer fabrics containment systems.
基金the National Natural Science Foundation of China(Grants 51906104,11532007,12025202 and 11772156)the Natural Science Foundation of Jiangsu Province(Grant BK20190385)+2 种基金Aeronautics Power Foundation(Grants 6141B09050387,6141B09050341)Jiangsu Provincial 333 High-level Talent Cultivation Project(Grant BRA2018031)the Priority Academic Program Development of Jiangsu Higher Education Institutions,and the Fundamental Research Funds for the Central Universities(Grants 1002-YAH18026 and 1002-56XAA19050).
文摘The submerged inlet is an attractive configuration for advanced helicopters due to its high stealth performance and low external drag.In this paper,a submerged inlet,integrated with a ROBIN helicopter fuselage and a simplified power output shaft,is experimentally and numerically investigated to obtain the basic flow characteristics under a freestream velocity of 23.6 m/s.The results indicate that the pylon ahead of the inlet induces a horseshoe vortex.Though the vortex is ingested into the inlet,it has little effect on the internal flows and can be neglected.When the airflow enters into the inlet,it interacts with the shaft with a large incidence angle,yielding a vortex pair.At the leeside of the shaft,the two side flows of the shaft impinge at the center plane,generating a local high-pressure region at the azimuthal angle of 180°,which forces the boundary layer to roll up a counter-rotating vortex pair.In addition,the airflow adjacent to the cowl lip accelerates rapidly,resulting in a local low-pressure region at the azimuthal angle of 0°.Therefore,the inlet duct has a strong circumferential pressure gradient,which originates from an azimuthal angle of 180°to 0°and induces a vortex pair at the azimuthal angle of 0°.The three vortex pairs are the main origins of the distortion at the duct exit plane,among which the one near the cowl lip with the azimuthal angle of 0°plays the dominant role.Additionally,as the velocity ratio increases from 3.9 to 5.5,the circumferential pressure gradient and the cowl lip vortex get intensified,which causes that the total-pressure recovery coefficient drops by 0.5%and the distortion index increases by 28%.
基金supported by the National Natural Science Foundation of China(No.91960110)the National Science and Technology Major Project(No. 2017-I0006-0007)the Fundamental Research Funds for the Central Universities(NP2022418)。
文摘This paper addresses the gas path component and sensor fault diagnosis and isolation(FDI) for the auxiliary power unit(APU). A nonlinear dynamic model and a distributed state estimator are combined for the distributed control system. The distributed extended Kalman filter(DEKF)is served as a state estimator,which is utilized to estimate the gas path components’ flow capacity. The DEKF includes one main filter and five sub-filter groups related to five sensors of APU and each sub-filter yields local state flow capacity. The main filter collects and fuses the local state information,and then the state estimations are feedback to the sub-filters. The packet loss model is introduced in the DEKF algorithm in the APU distributed control architecture. FDI strategy with a performance index named weight sum of squared residuals(WSSR) is designed and used to identify the APU sensor fault by removing one sub-filter each time. The very sensor fault occurs as its performance index WSSR is different from the remaining sub-filter combinations. And the estimated value of the soft redundancy replaces the fault sensor measurement to isolate the fault measurement. It is worth noting that the proposed approach serves for not only the sensor failure but also the hybrid fault issue of APU gas path components and sensors. The simulation and comparison are systematically carried out by using the APU test data,and the superiority of the proposed methodology is verified.
基金co-supported by the National Natural Science Foundation of China (No. 12172175)the National Science and Technology Major Project, China (No. J2019-II0014-0035)the Science Center for Gas Turbine Project, China (Nos. P2022-C-II-002-001, P2022-A-II-002-001)
文摘Cowl-induced incident Shock Wave/Boundary Layer Interactions (SWBLI) under the influence of gradual expansion waves are frequently observed in supersonic inlets. However, the analysis and prediction of interaction lengths have not been sufficiently investigated. First, this study presents a theoretical scaling analysis and validates it through wind tunnel experiments. It conducts detailed control volume analysis of mass conservation, considering the differences between inviscid and viscous cases. Then, three models for analysing interaction length under gradual expansion waves are derived. Related experiments using schlieren photography are conducted to validate the models in a Mach 2.73 flow. The interaction scales are captured at various relative distances between the shock impingement location and the expansion regions with wedge angles ranging from 12° to 15° and expansion angles of 9°, 12°, and 15°. Three trend lines are plotted based on different expansion angles to depict the relationship between normalised interaction length and normalised interaction strength metric. In addition, the relationship between the coefficients of the trend line and the expansion angles is introduced to predict the interaction length influenced by gradual expansion waves. Finally, the estimation of normalised interaction length is derived for various coefficients within a unified form.
基金supported by the Basic Research on Dynamic Real-time Modeling and Onboard Adaptive Modeling of Aero Engine,China(No.QZPY202308)。
文摘Variable Cycle Engine(VCE)serves as the core system in achieving future advanced fighters with cross-generational performance and mission versatility.However,the resultant complex configuration and strong coupling of control parameters present significant challenges in designing acceleration and deceleration control schedules.To thoroughly explore the performance potential of engine,a global integration design method for acceleration and deceleration control schedule based on inner and outer loop optimization is proposed.The outer loop optimization module employs Integrated Surrogate-Assisted Co-Differential Evolutionary(ISACDE)algorithm to optimize the variable geometry adjustment laws based on B-spline curve,and the inner loop optimization module adopts the fixed-state method to design the open-loop fuel–air ratio control schedules,which are aimed at minimizing the acceleration and deceleration time under multiple constraints.Simulation results demonstrate that the proposed global integration design method not only furthest shortens the acceleration and deceleration time,but also effectively safeguards the engine from overlimit.
基金supported by National Natural Science Foundation of China(No.52302472)。
文摘The development of the adaptive cycle engine is a crucial direction of advanced fighter power sources in the near future.However,this new technology brings more uncertainty to the design of the control system.To address the versatile thrust demand under complex dynamic characteristics of the adaptive cycle engine,this paper proposes a direct thrust estimation and control method based on the Model-Free Adaptive Control(MFAC)algorithm.First,an improved Sliding Mode Control-MFAC(SMC-MFAC)algorithm has been developed by introducing a sliding mode variable structure into the standard Full Format Dynamic Linearization-MFAC(FFDL-MFAC)and designing self-adaptive weight coefficients.Then a trivariate double-loop direct thrust control structure with a controller-based thrust estimator and an outer command compensation loop has been established.Through thrust feedback and command correction,accurate control under multi-mode and operation conditions is achieved.The main contribution of this paper is the improved algorithm that combines the tracking capability of the MFAC and the robustness of the SMC,thus enhancing the dynamic performance.Considering the requirements of the online thrust feedback,the designed MFAC-based thrust estimator significantly speeds up the calculation.Additionally,the proposed command correction module can achieve the adaptive thrust control without affecting the operation of the inner loop.Simulations and Hardware-in-Loop(HIL)experiments have been performed on an adaptive cycle engine component-level model to investigate the estimation and control effect under different modes and health conditions.The results demonstrate that both the thrust estimation precision and operation speed are significantly improved compared with Extended Kalman Filter(EKF).Furthermore,the system can accelerate the response of the controlled plant,reduce the overshoot,and realize the thrust recovery within the safety range when the engine encounters the degradation.
基金supported by the National Natural Science Foundation of China(Nos.52222504 and 52241502)the Natural Science Talents Foundation of Shaanxi Province(No.2021JC-04).
文摘In order to realize the automatic recognition and classification of cracks with different depths,in this study,several deep convolutional neural networks including AlexNet,ResNet,and DenseNet were employed to identify and classify cracks at different depths and in various materials.An analysis process for the automatic classification of crack damage was presented.The image dataset used for model training was obtained from scanning experiments on aluminum and titanium alloy plates using an ultrasonic phased-array flaw detector.All models were trained and validated with the dataset;the proposed models were compared using classification precision and loss values.The results show that the automatic recognition and classification of crack depth can be realized by using the deep learning algorithm to analyze the ultrasonic phased array images,and the classification precision of DenseNet is the highest.The problem that ultrasonic damage identification relies on manual experience is solved.
基金Supported by National Natural Science Foundation of China(Grant No.52275142)Science Center for Gas Turbine Project(Grant Nos.P2022-AIII-003-001,P2022-B-III-005-001)+1 种基金National Science and Technology Major Project(Grant Nos.J2019-IV-0009-0077,Y2022-IV-0002-0019,J2019-IV-0008-0076)National Basic Scientific Research Project(Grant No.JCKY2021601B204)。
文摘Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore its creep properties.In this work,a series of RHT experiments were carried out on a directionally solidified(DS)nickel-based superalloy under different solution temperatures and primary aging temperatures based on the standard heat treatment(SHT)process parameters to investigate the mechanism of temperature influence on DS's microstructure after RHT.It is indicated that a more uniform microstructure can be obtained under higher solution temperatures and lower primary aging temperatures compared to the SHT process.Furthermore,by employing the image processing methods to quantify microstructural parameters,a comprehensive indicator parameter for the RHT effect(marked as Prej)was proposed to characterize the effects of RHT on DS superalloy's microstructure and creep property combined with the entropy weight method.Based on this,a regression model to describe the relationship between RHT process parameters and Prej was constructed by using the response surface methodology(RSM).It is revealed that the optimal solution temperature and primary aging temperature for this DS superalloy are 1283°C and 1095°C,respectively.Then the conclusion was validated through complete creep experiments on the DS superalloy,which showed the creep life after RHT reaches 95.5%of the SHT specimen,and the total life has increased by 20.6%.
基金National Natural Science Foundation of China(Grant No.22175059)to provide fund for conducting experiments.
文摘The migration of nitroglycerin(NG) has always been the critical issue that harmfully impacts the structural integrity and operational reliability of the solid rocket motor, which is mainly composed by Nitrate Ester Plasticized Polyether(NEPE) propellant/Hydroxyl-terminated Polybutadiene(HTPB) liner/Ethylene Propylene Diene Monomer(EPDM) insulation bonding system. This paper proposes an innovative surface modification method attempting to modify the EPDM insulation layer coated with reduced graphene oxide(RGO), which exhibits ability to weaken the NG absorption by EPDM insulation layer,blocking the pathway of NG migration into EPDM insulation materials. The microstructure of RGO-coated layer was analyzed and the formation mechanism was investigated. The RGO-coated layer is well bonded to the HTPB liner, and its anti-migration performance to NG at different temperatures has been evaluated. Comparing with blank samples under the same storage conditions, the RGO-coated layers can reduce the diffusion coefficient of NG by up to 87.3% and increase the diffusion activation energy of NG by14.8 kJ,mol^(-1). This research provides a new strategy to effectively inhibit NG migration in NEPE propellant/HTPB liner/EPDM insulation bonding system.
基金financially supported by the Natural Science Foundation of Shandong Province(No.ZR2022MB034)。
文摘The advancement of functional adhesives featuring recyclable and repairable properties is of great significance in interfacial science and engineering.Herein,a series of high-strength,recyclable fluorine-containing adhesives(ESOx-FPF)were designed and synthesized by crosslinking two prepolymers,FPF-B(derived from side-chain fluorinated diol,isocyanate,and aminoboric acid)and ESO-B(synthesized from biobased epoxy soybean oil and aminoboric acid),through dynamic boro-oxygen bonds.The resulting adhesive exhibited an optimal tensile strength of 42 MPa and the shear strength on steel plates reached as high as 3.89 MPa.More importantly,benefiting from the dynamic reversibility of the boron-oxygen bonds along with the hydrogen bonds interaction,ESOx-FPF can be welded with the assistance of solvents and recycled for multiple cycles.The outstanding healing efficiency and excellent reprocessability of these functional adhesives were confirmed by mechanical testing.Moreover,the as-prepared adhesives demonstrated universal and remarkable adhesion to various substrates,such as aromatic polyamide,aluminum plates and polycarbonate,meanwhile,they could be easily disassembled and recycled using ethanol without damaging the substrates surface.This study not only provides a simple strategy for the synthesis of eco-friendly adhesives with weldable and recyclable properties,but also sheds light on the development of other functional materials utilizing dynamic covalent chemistry.
基金financially supported by National Key Research and Development Program of China(Grant No.2023YFB4604800)National Natural Science Foundation of China(Grant No.52275331)financial support from the Hong Kong Scholars Program(Grant No.XJ2022014).
文摘Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local resonance can effectively balance the volume occupation and low-frequency absorption performance.However,these materials often exhibit a very narrow and fixed absorption band.Inspired by Helmholtz resonators and bistable structures,we propose bistable reconfigurable acoustic metamaterials(BRAMs)that offer multiband low-frequency absorption.These BRAMs are fabricated using shape-memory polylactic acid(SM-PLA)via four-dimension(4D)printing technology.Consequently,the geometry and absorption performance of the BRAMs can be adjusted by applying thermal stimuli(at 55℃)to switch between two stable states.The BRAMs demonstrate excellent low-frequency absorption with multiband characteristics,achieving an absorption coefficient of 0.981 at 136 Hz and 0.998 at 230 Hz for stable state I,and coefficients of 0.984 at 156 Hz and 0.961 at 542 Hz for stable state II.It was found that the BRAMs with different inclined plate angles had linear recovery stages,and the recovery speeds range from 0.75 mm/s to 1.1 mm/s.By combining a rational structural design and 4D printing,the reported reconfigurable acoustic metamaterials will inspire further studies on the design of dynamic and broadband absorption devices.
基金supported by the Fundamental Research Funds for the Central Universities(NO.NS2018018)
文摘Aero-engine gas path health monitoring plays a critical role in Engine Health Management(EHM). To achieve unbiased estimation, traditional filtering methods have strict requirements on measurement parameters which sometimes cannot be measured in engineering. The most typical one is the High-Pressure Turbine(HPT) exit pressure, which is vital to distinguishing failure modes between different turbines. For the case of an abrupt failure occurring in a single turbine component, a model-based sensor measurement reconstruction method is proposed in this paper. First,to estimate the missing measurements, the forward algorithm and the backward algorithm are developed based on corresponding component models according to the failure hypotheses. Then,a new fault diagnosis logic is designed and the traditional nonlinear filter is improved by adding the measurement estimation module and the health parameter correction module, which uses the reconstructed measurement to complete the health parameters estimation. Simulation results show that the proposed method can well restore the desired measurement and the estimated measurement can be used in the turbofan engine gas path diagnosis. Compared with the diagnosis under the condition of missing sensors, this method can distinguish between different failure modes, quantify the variations of health parameters, and achieve good performance at multiple operating points in the flight envelope.
基金the financial support for this project from the National Natural Science Foundation of China (Nos.51276090 and U1508212)
文摘An experimental study is made to investigate the film cooling performance of imperfect holes due to in-hole blockage over a flat plate. A specifically pyramid-shaped element is used to simulate the in-hole blockage. Six in-hole blockage orientations（such as leading-inlet, leading-middle,leading-exit, trailing-inlet, trailing-middle and trailing-exit） and four blocking ratios（ranging from 0.1 to 0.4） are taken into considerations. Based on the experimental results, the influences of in-hole blockage on the film cooling effectiveness and discharge coefficient under typical blowing ratios are analyzed. It is confirmed that the in-hole blockage results in a reduction of discharge coefficient related to the perfect film cooling holes, especially for the leading-exit and trailing-inlet orientations with a big blocking ratio. However, in the view of film cooling effectiveness, the in-hole blockage shows complicated affecting roles. In general, except for the leading-exit orientation, the in-hole blockages produce detrimental influence on the film cooling effectiveness.
基金the financial supports for this project from the National Natural Science Foundation of China(No.51776097)the Open Fund of Jiangsu Province Key Laboratory of Aerospace Power System(No.APS20A7002)the Postgraduate Research and Practice Innovation Project of Jiangsu Province(No.KYCX17 0280)
文摘To address the curvature effect on single-row chevron-nozzle jet impingement heat transfer on concave surface,a series of experiments are conducted in the present investigation.Four concave surfaces including one semi-cylindrical concave surface and three parabolic concave surfaces with different width-to-depth ratios are tested under three typical Reynolds numbers(Re=5000,10000 and 15000)and several dimensionless nozzle-to-surface distances ranging from 1 to 8.The results show that the concave curvature has a clear impact on chevron-nozzle jet impingement heat transfer,tightly dependent on jet Reynolds number and impinging distance.In general,the semicylindrical concave surface produces the highest longitudinally-averaged Nusselt number at the leading line of concave surface.Under a low jet Reynolds number,the parabolic concave surface with a highly curved curvature produces higher longitudinally-averaged Nusselt number at the leading line and more uniform longitudinally-averaged Nusselt number distribution along the curvilinear direction.However,the longitudinally-averaged Nusselt number at the leading line of concave surface is the lowest for the highly curved surface under a high jet Reynolds number and large impinging distance.In comparison with the round-nozzle,chevron nozzle plays a more significant role on improving jet impingement heat transfer at small impinging distances.
基金the supports from the Jiangsu Province Key Laboratory of Aerospace Power System of China(No.NJ20140019)the National Natural Science Foundation of China(No.51205190)
文摘In order to analyze the stress and strain fields in the fibers and the matrix in composite materials,a fiber-scale unit cell model is established and the corresponding periodical boundary conditions are introduced.Assuming matrix cracking as the failure mode of composite materials,an energy-based fatigue damage parameter and a multiaxial fatigue life prediction method are established.This method only needs the material properties of the fibers and the matrix to be known.After the relationship between the fatigue damage parameter and the fatigue life under any arbitrary test condition is established,the multiaxial fatigue life under any other load condition can be predicted.The proposed method has been verified using two different kinds of load forms.One is unidirectional laminates subjected to cyclic off-axis loading,and the other is filament wound composites subjected to cyclic tension-torsion loading.The fatigue lives predicted using the proposed model are in good agreements with the experimental results for both kinds of load forms.
基金supported by the Fundamental Research Enhancement Project,China(No.2017-JCJQ-ZD-047-21).
文摘A nonlinear model predictive control method based on fuzzy-Sequential Quadratic Programming(SQP)for direct thrust control is proposed in this paper for the sake of improving the accuracy of thrust control.The designed control system includes four parts,namely a predictive model,rolling optimization,online correction,and feedback correction.Considering the strong nonlinearity of engine,a predictive model is established by Back Propagation(BP)neural network for the entire flight envelope,whose input and output are determined with random forest algorithm and actual situation analysis.Rolling optimization typically uses SQP as the optimization algorithm,but SQP algorithm is easy to trap into local optimization.Therefore,the fuzzy-SQP algorithm is proposed to prevent this disadvantage using fuzzy algorithm to determine the initial value of SQP.In addition to the traditional three parts of model predictive control,an online correction module is added to improve the predictive accuracy of the predictive model in the predictive time domain.Simulation results show that the BP predictive model can reach a certain degree of predictive accuracy,and the proposed control system can achieve good tracking performance with the limited parameters within the safe range。
基金support of the National Science and Technology Major Project,China(No.2019-II-0007-0027)the Defense Industrial Technology Development Program,China(No.JCKY2019605D001)+3 种基金the Advanced Jet Propulsion Creativity Center,Aero Engine Academy of China(No.HKCX2020-02-011)the Aeronautics Power Foundation,China(No.6141B09050383)the Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory of China,the Jiangsu Funding Program for Excellent Postdoctoral Talent,China(No.2022ZB214)the China Postdoctoral Science Foundation。
文摘Bypass Dual Throat Nozzle(BDTN)is a novel type of fluidic thrust vectoring nozzle.To improve the infrared stealth performance of BDTN,a nozzle based on BDTN is proposed and numerically simulated.Each cross-section along the x-axis of the novel nozzle becomes a trapezoid,which is named“BDTN-TRA.”The main numerical simulation results show that BDTN-TRA can produce a thrust vectoring angle when the upper or lower bypass valve is open.The angle difference between the two conditions mentioned above is usually approximately 1°-2°.Even if the two bypasses are closed,BDTN-TRA can produce a small thrust vectoring angle at around 3°-5°.When the sidewall angle increases from 60°to 90°,the thrust coefficient and thrust vectoring angle under each work condition usually decrease.A larger aspect ratio indicates better performance.As the aspect ratio increases over 7.2,the performance of BDTN-TRA is quite close to that of BDTN with rectangular cross-sections at the same aspect ratio.These features will benefit the control and trimming for future aircraft design,especially for the flying wing layout aircraft.Last but not least,BDTN-TRA has a more extraordinary mixing performance compared with BDTN.The distributions of static temperature and axial velocity along the x-axis of BDTN-TRA with sidewall angle of 60°decrease faster than those of BDTN.When the total temperature of the inlet equals 1600 K,the static temperature difference between BDTN-TRA with sidewall angles of 60°and 90°is over 360 K at twice the length of the nozzle downstream of the nozzle exit,which is the reflection for excellent infrared stealth for the fighter.
基金supported by the National Science and Technology Major Project, China (No. 2017-V-0004-0054)
文摘A novel turbofan Direct Thrust Control(DTC)architecture based on Linear ParameterVarying(LPV)approach for a two-spool turbofan engine thrust control is proposed in this paper.Instead of transforming thrust command to shaft speed command and pressure ratio command,the thrust will be directly controlled by an optimal controller with two control variables.LPV model of the engine is established for the designing of thrust estimator and controller.A robust LPV H∞filter is introduced to estimate the unmeasurable thrust according to measurable engine states.The thrust estimation error system is proved to be Affinely Quadratically Stable(AQS)in the whole parameter box with a prescribed H∞performance indexγ.Due to the existence of overdetermined equations,the solving of controller parameters is a multi-solution problem.Therefore,Particle Swarm Optimization(PSO)algorithm is used to optimize the controller parameters to obtain satisfactory control performance based on the engine’s LPV model.Numerical simulations show that the thrust estimator can acquire smooth and accurate estimating results when sensor noise exists.The optimal controller can receive desired control performance both in steady and transition control tasks within the engine working states above the idle,verifying the effectiveness of the proposed DTC architecture’s application in thrust direct control problem.
