An Improvement Method Based on Similarity Theory for Equilibrium Manifold Expansion Model

2019 ◽  
Author(s):  
Linhai Zhu ◽  
Jinfu Liu ◽  
Weixing Zhou ◽  
Daren Yu
Keyword(s):  
Similarity Theory ◽  
Equilibrium Manifold ◽  
Improvement Method ◽  
Expansion Model

scholarly journals A Corrected Equilibrium Manifold Expansion Model for Gas Turbine System Simulation and Control

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4904
Author(s):  
Linhai Zhu ◽  
Jinfu Liu ◽  
Yujia Ma ◽  
Weixing Zhou ◽  
Daren Yu
Keyword(s):  
Gas Turbine ◽  
Similarity Theory ◽  
State Space Model ◽  
Similarity Criterion ◽  
System Control ◽  
Turbine Engine ◽  
Engine Simulation ◽  
Identification Method ◽  
Equilibrium Manifold ◽  
Expansion Model

During recent decades, the equilibrium manifold expansion (EME) model has been considered as a powerful identification tool for complex industrial systems with the aim of system control and simulation. Based on a two-step “dynamic and static” identification method, an approximate nonlinear state-space model is built by using multiple polynomials. However, the existing identification method is only suitable for single-input (SI) systems, but not for multi-input (MI) systems, where EME models cannot guarantee global calculation stability. For solving such a problem, this paper proposes a corrected equilibrium manifold expansion (CEME) model based on gas turbine prior knowledge. The equilibrium manifold is extended in dimension by introducing similarity equations instead of the high dimensional polynomial fitting. The dynamic similarity criterion of similarity theory guarantees the global stability of the CEME model. Finally, the comparative test between the CEME model and the existing MI-EME model is carried out through case studies involving data that are generated by a general turbofan engine simulation. Simulations show superior precision and calculation stability of the proposed model in capturing nonlinear behaviors of the gas turbine engine.

Nonlinear System Modeling and Application Based on System Equilibrium Manifold and Expansion Model

2013 ◽  
Vol 9 (2) ◽  
Author(s):  
Xiaofeng Liu ◽  
Ye Yuan
Keyword(s):  
Nonlinear System ◽  
System Modeling ◽  
Nonlinear Behavior ◽  
Aircraft Engine ◽  
Good Precision ◽  
Identification Procedure ◽  
Nonlinear System Modeling ◽  
Equilibrium Manifold ◽  
System Equilibrium ◽  
Expansion Model

A new modeling method for a nonlinear system by using equilibrium manifold (EM) and its expansion model (EME model) was presented. The property of the EME model was discussed, and the effect of mapping design to the model has been discussed. This paper also has researched the adaptivity analysis to the EME model. Then an approximate nonlinear model for an aircraft engine is applied, followed by an identification procedure for an aircraft engine. Simulations showed good precision of this model in capturing the nonlinear behavior of nonlinearities and had the simpler structure.

A nonlinear switching control strategy of regulation and safety protection for aero-engines based on the equilibrium manifold expansion model

2017 ◽  
Vol 232 (4) ◽  
pp. 355-368 ◽  
Author(s):  
Chao Chen ◽  
Jun Zhao
Keyword(s):  
High Pressure ◽  
Control Strategy ◽  
Switching Control ◽  
Equilibrium Manifold ◽  
Safety Protection ◽  
Switching Control Strategy ◽  
Nonlinear Switching ◽  
Aero Engines ◽  
Expansion Model ◽  
Safety Boundary

This article proposes a nonlinear switching control strategy to solve the regulation control problem with safety constraint for aero-engines based on the equilibrium manifold expansion model. That is a kind of nonlinear model with satisfactory accuracy. The design procedure includes design of sub-controllers such as the nonlinear high-pressure spool speed tracking controller, high pressure turbine outlet temperature safety protection controller and the nonlinear dynamic feedback recovery controller. Also, switching law and dynamic controller state reset law are properly designed. Under the proposed strategy, system trajectory starting from temperature safety boundary will never return to the safety boundary. The designed reset law ensures a smooth switching from protection mode to recovery mode. Switch-off moment of the protection controller can be arbitrarily selected according to the tracking performance requirement. Freedom degree of selection is enlarged. The sub-controllers corresponding to objectives of regulation and safety protection are designed separately with more freedom degree and less conservatism. The effectiveness and the robustness of the proposed strategy are verified through a case study for a two-spool turbofan engine.

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

Energies ◽  
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.

Similarity theory in neutron kinetics and its implications for RFNC—VNIIEF applied research

2011 ◽  
Vol 181 (9) ◽  
pp. 953
Author(s):  
Nikolai B. Babichev ◽  
Pavel S. Bondarev ◽  
Vasilii P. Neznamov
Keyword(s):  
Applied Research ◽  
Similarity Theory ◽  
Neutron Kinetics
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