Study on integrated control for supersonic inlet and turbofan engine model

Considering the supersonic inlet model with normal shock position feedback, the integrated control method of inlet and turbofan engine is studied. The integrated model includes the supersonic inlet model and the component level model of engine. Combining the relationship between the normal shock position and the total pressure recovery coefficient, the supersonic inlet and engine model is constructed. On the basis of this model, the normal shock position closed-loop control simulation is carried out, which shows that the normal shock position matching point could be stabilized near the optimal value while restraining the inlet stream disturbance. Furthermore, based on the H∞ control algorithm, an inlet and engine integrated control is designed to control the installation thrust and turbine pressure ratio with fuel, nozzle throat area, and normal shock position as control variables. The simulation results show that the response time of the integrated control is faster than the independent control. The integrated control has stronger ability to restrain the atmospheric disturbance, which could ensure the stable and reliable operation of the propulsion system.

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Study on Inlet and Engine Integrated Model with Normal Shock Position Feedback

International Journal of Aerospace Engineering ◽

10.1155/2020/5313941 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Haoying Chen ◽

Haibo Zhang ◽

Zhihua Xi ◽

Qiangang Zheng

Keyword(s):

Flow Rate ◽

Integrated Model ◽

Normal Shock ◽

Dynamic Identification ◽

Component Level ◽

Recovery Coefficient ◽

Loop Control ◽

Level Model ◽

Shock Position ◽

And Control

In order to consider the inlet and engine integrated model of supersonic airliner, the dynamic identification and control of inlet normal shock are studied. The research is based on the bleed air flow rate under supersonic conditions. With the two-dimensional CFD model of supersonic inlet, the dynamic and static effects of the bleeding flow rate on the normal shock position were investigated. The transfer function was identified, and simultaneously the paper carried out a comprehensive study of inlet and engine integrated model, which is established based on the inlet shock position model and engine component level model. The relationship between normal shock position and total pressure recovery coefficient has been taken into consideration in this model. Based on the inlet and engine integrated model, the closed-loop control simulation of normal shock position is carried out. The results show that the model could resist the disturbance of the inlet flow and keep the inlet and engine matching operation point stable near the optimal value.

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A new solution to the coupled problems of aero-propulsion system deceleration under supersonic state

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211052840 ◽

2021 ◽

pp. 095440622110528

Author(s):

Fengyong Sun ◽

Chunsheng Ji ◽

Tengfei Zhang

Keyword(s):

Integrated Control ◽

Control Variable ◽

Propulsion System ◽

Effective Control ◽

Coupled Problems ◽

Component Level ◽

Turbofan Engine ◽

Control Scheme ◽

Level Model ◽

Rapid Drop

Under supersonic state, the aero-propulsion system exhibits different coupled characters in deceleration from that in acceleration. However, the deceleration control has not been fully studied. In order to solve the coupled problems, an integrated component-level model including inlet and turbofan engine was established. Based on the integrated model, the particularity of inlet adjustment during deceleration was analyzed. And the analyzed results showed that the inlet regulation is not necessary to keep the inlet and engine working in well-matched at any time under supersonic state. Due to the coupled relationship between inlet and turbofan engine, a new optimal integrated control scheme is proposed in this paper. The inlet ramp angle is taken as an optimal control variable as the same as main fuel mass flow and nozzle throat area. The simulation results indicate that inlet ramp angle regulation showed a more effective control quality in the rapid drop of aero-propulsion–installed thrust. Furthermore, the deceleration could be completed in a shorter control time.

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The Shock Position in Overexpanded Nozzles.

Journal of the Royal Aeronautical Society ◽

10.1017/s0368393100078445 ◽

1963 ◽

Vol 67 (628) ◽

pp. 268-269 ◽

Cited By ~ 4

Author(s):

M. Arens

Keyword(s):

Nozzle Exit ◽

Pressure Ratio ◽

Separated Flow ◽

Normal Shock ◽

Nozzle Flow ◽

Nozzle Pressure Ratio ◽

Continuous Increase ◽

Nozzle Pressure ◽

Shock Position ◽

Exit Mach Number

References 1 and 2 discuss the shock position in over-expanded nozzles, and in particular the transition from nozzle flow characterised by a normal shock in the nozzle to nozzle flow characterised by oblique shocks and separation from the wall. As is well known, the shock position and pressure distribution for unseparated overexpanded flow can be adequately explained using one-dimensional fluid mechanics. Ref. 2, while suggesting a criterion for transition to separated flow, maintains that the separation point is not predictable. The criterion suggested by ref. 2 is that whenever the pressure ratio p2/p0, associated with expansion to the nozzle exit plane followed by normal shock compression at the exit Mach number exceeds the nozzle pressure ratio pb/p0, separated flow will occur. Based on this criterion and the double valuedness of the p2/p0 locus, it is argued that at a nozzle pressure ratio of 0·624, a continuous increase of nozzle exit to throat area ratio will provide for transition from unseparated normal shock flow to separated flow and back to unseparated normal shock flow.

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Research on Integrated Control Method of Tiltrotor with Variable Rotor Speed Based on Two-Speed Gearbox

International Journal of Turbo and Jet Engines ◽

10.1515/tjj-2018-0004 ◽

2018 ◽

Vol 0 (0) ◽

Cited By ~ 2

Author(s):

Yong Wang ◽

Qiangang Zheng ◽

Haibo Zhang ◽

Zhigui Xu

Keyword(s):

Control Method ◽

Integrated Control ◽

Classical Mechanics ◽

Fast Response ◽

Rotor Speed ◽

Component Level ◽

Variable Model ◽

Element Analysis ◽

Shift Control ◽

Turboshaft Engine

Abstract The process of rotor speed variation under tiltrotor cruise state has been studied, and the integrated variable speed control method of tiltrotor based on two-speed gearbox is proposed. Firstly, a nonlinear model predictive controller (NMPC) based on state variable model of the component-level model of the turboshaft engine is designed. Then based on the integrated engine model, the two-speed dual path tiltrotor driveline comprehensive simulation model was developed by utilizing gear kinematics theory, blade element analysis and the theory of classical mechanics. Finally, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy in tiltrotor cruise state were analyzed and compared with conventional PID controller. It is shown that the rotors’ speed can synchronously vary by 50 percent under the PSC strategy in tiltrotor cruise state. Meanwhile, disengaging the engine in turn by freewheel clutches can reduce the rotors’ speed from 190 rpm to 102.5 rpm along the specified path under the SSC strategy. The overshoot and droop amount of the power turbine speed can be reduced to less than 1.5 % with the steady error no more than 0.2 % through NMPC, which realizes the fast response control of the turboshaft engine.

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Control-Oriented Modeling for Nonlinear MIMO Turbofan Engine Based on Equilibrium Manifold Expansion Model

Energies ◽

10.3390/en14196277 ◽

2021 ◽

Vol 14 (19) ◽

pp. 6277

Author(s):

Chengkun Lv ◽

Ziao Wang ◽

Lei Dai ◽

Hao Liu ◽

Juntao Chang ◽

...

Keyword(s):

Pressure Ratio ◽

Multiple Input Multiple Output ◽

Rotor Speed ◽

Model Accuracy ◽

Component Level ◽

Turbofan Engine ◽

Turbofan Engines ◽

Input Noise ◽

Equilibrium Manifold ◽

Expansion Model

This paper investigates the control-oriented modeling for turbofan engines. The nonlinear equilibrium manifold expansion (EME) model of the multiple input multiple output (MIMO) turbofan engine is established, which can simulate the variation of high-pressure rotor speed, low-pressure rotor speed and pressure ratio of compressor with fuel flow and throat area of the nozzle. Firstly, the definitions and properties of the equilibrium manifold method are presented. Secondly, the steady-state and dynamic two-step identification method of the MIMO EME model is given, and the effects of scheduling variables and input noise on model accuracy are discussed. By selecting specific path, a small amount of dynamic data is used to identify a complete EME model. Thirdly, modeling and simulation at dynamic off-design conditions show that the EME model has model accuracy close to the nonlinear component-level (NCL) model, but the model structure is simpler and the calculation is faster than that. Finally, the linearization results are obtained based on the properties of the EME model, and the stability of the model is proved through the analysis of the eigenvalues, which all have negative real parts. The EME model constructed in this paper can meet the requirements of real-time simulation and control system design.

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Evaluation on the performance fluctuation after water ingestion for a turbofan engine compressor during flight descent

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410020977982 ◽

2020 ◽

pp. 095441002097798

Author(s):

Lu Yang ◽

Qun Zheng ◽

Aqiang Lin

Keyword(s):

Droplet Diameter ◽

Pressure Ratio ◽

Critical Role ◽

Water Film ◽

Heavy Rain ◽

Diameter Distribution ◽

Turbofan Engine ◽

Water Ingestion ◽

The Core ◽

Engine Compressor

Turbofan engine compressor is most severely threatened by the entry of liquid water during flight descent. This study aims to deeply understand the fluctuations of compressor performance parameters caused by water ingestion through frequency spectrum analysis. The water content and droplet diameter distribution are determined based on the real heavy rain environment. Results reveal that most of the droplets actually entering the core compressor have a particle size of less than 100 μm. In addition, the formation and motion of water film plays a critical role in affecting the fluctuation characteristics. Water ingestion deteriorates the compression performance and aggravates the unsteady fluctuations of the fan. However, the performance of the core compressor is less affected by water ingestion, but their fluctuations are still exacerbated. For some important parameters, such as inlet mass flow rate, total pressure ratio, total temperature ratio, compression work and efficiency, their main frequency of fluctuation are switched from the original blade passing frequency to the rotor passing frequency, and their amplitudes are correspondingly amplified to varying degrees. These phenomena can be observed in both the fluctuations of the fan and core compressor. Moreover, the operating point of them will be in the long-period and large-amplitude fluctuations, which leads them experiences the non-optimal state for a long time and threatens their operating stability.

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Aero-engine dynamic model based on an improved compact propulsion system dynamic model

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1177/0959651820984081 ◽

2021 ◽

pp. 095965182098408

Author(s):

Qiangang Zheng ◽

Yong Wang ◽

Chongwen Jin ◽

Haibo Zhang

Keyword(s):

Dynamic Model ◽

Propulsion System ◽

System Dynamic ◽

Inlet Temperature ◽

System Dynamic Model ◽

Component Level ◽

Engine Model ◽

Surge Margin ◽

Aero Engine ◽

Engine Dynamic

The modern advanced aero-engine control methods are onboard dynamic model–based algorithms. In this article, a novel aero-engine dynamic modeling method based on improved compact propulsion system dynamic model is proposed. The aero-engine model is divided into inlet, core engine, surge margin and nozzle models for establishing sub-model in the compact propulsion system dynamic model. The model of core engine is state variable model. The models of inlet, surge margin and nozzle are nonlinear models which are similar to the component level model. A new scheduling scheme for basepoint control vector, basepoint state vector and basepoint output vector which considers the change of engine total inlet temperature is proposed to improve engine model accuracy especially the steady. The online feedback correction of measurable parameters is adopted to improve the steady and dynamic accuracy of model. The modeling errors of improved compact propulsion system dynamic model remain unchanged when engine total inlet temperature of different conditions are the same or changes small. The model accuracy of compact propulsion system dynamic model, especially the measurable parameters, is improved by online feedback correction. Moreover, the real-time performance of compact propulsion system dynamic model and improved compact propulsion system dynamic model are much better than component level model.

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