Research On Adaptive Control Method Of Transcritical Speed Of ATR Engine

Air turbine rocket engine(ATR)has the advantages of wide flight envelope,high maneuverability,high thrust and specific impulse,etc.,and has broad prospects for application in near-space vehicles.Since the center of mass of each micro-segment of the rotor in the rotating system cannot be strictly on the rotating shaft,there will be lateral interference when the rotor rotates,and it will cause strong vibration of the system at certain speeds.The speed when this happens is the critical speed.Rotating speed.In order to improve the service life of the ATR engine,it is necessary to automatically identify the critical speed and adaptively change the controller parameters.This paper studies the adaptive control method of the ATR engine.The main research contents are as follows:Firstly,established the thermophysical properties model and combustion calculation model of an ATR engine,and built the component models in sequence according to the internal flow path,including the variable-geometry inlet,compressor,gas generator,turbine,combustion chamber,and variable-geometry exhaust nozzle.The dynamic model of the ATR engine with variable geometry has been established using the volume method,and the steady-state and dynamic performance have been calculated.The effects of variable-geometry and controller parameters on the dynamic performance of the ATR engine have been analyzed.The airflow path,rich-burn gas path,and gas path of the engine have been analyzed,and the thermodynamic parameter calculation of its internal working fluid has been simplified.Finally,the calculation results of the simplified model have been compared and analyzed with those of the original model.The results show that the dynamic model with variable geometry can simulate the dynamic process of the ATR engine without iteration,and can quickly and accurately obtain the dynamic performance of the engine under the condition of multivariable coupling.Secondly,by dividing the design parameters into six levels and evaluating them,the influence factors of engine design parameters are analyzed,including the influence of compressor pressure ratio,turbine pressure ratio,turbine inlet gas temperature and flight status on engine performance and other parameters.At the same time,the throttle characteristics,speed characteristics and height characteristics of the engine are analyzed.It was found that the common operating point of the engine will move to the left at a reduced relative conversion speed,which will lead to a decrease in the compressor pressure ratio,air flow and gas flow,which will rapidly reduce the engine performance.When the flight Mach number is low,as the Mach number increases,the thrust of the engine increases,while the specific impulse decreases slightly.When the flight Mach number is high,increasing the Mach number will cause the thrust of the engine to decrease,but the specific impulse will increase slightly.Finally,use the meshgrid function to create a three-dimensional grid,calculate the thrust-speed-betac surface in the steady-state program,and find the speed point that meets the thrust condition according to the thrust demand of the critical speed.A multiobjective optimization method for ATR engine controller parameters was established by using the fast non-dominated sorting genetic algorithm(NSGA-Ⅱ).This method can obtain a set of optimal controller parameter sets—Pareto frontier,and use the TOPSIS method(Technique for Order Preference by Similarity to Ideal Solution)based on the entropy weight method to process,and finally obtain the optimal controller for the current transition process parameter.Simulate the process of the ATR engine’s transcritical speed.When the critical speed is detected,the controller parameters will automatically replace the optimized parameters.Compared with continuing to use the previous controller parameters,the acceleration process of the ATR engine will be faster,more stable and more accurate.control process.