Modeling Research Of Micro Turbojet Engine Power System Based On Test Dat

The micro turbojet engine has the advantages of high thrust to weight ratio and small size,which plays an important role in various aircraft.And it has a broad market application prospect in the future.As the core part of the engine,the dynamical system has a significant impact on the development of aircraft.In this paper,based on the test data of the ground micro turbojet engine,the dynamical system model of the micro turbojet engine is established with the Matlab software.The main research work is as follows:(1)According to the composition and structure of the micro turbojet engine test stand,the working principle of the test stand is analyzed,and the starting process of the micro turbojet engine is described.The functions are introduced from the fuel supply system,the electronic control system and the data acquisition system.The data such as engine speed,thrust and fuel flow are obtained through the data acquisition system,which provides data support for the establishment of the model of the micro turbojet engine dynamical system.By analyzing the functions of each system of the engine,the design scheme of the test stand is established.(2)First of all,the working characteristics of the single-shaft turbojet engine is analyzed.The main working states of the engine are divided into takeoff,maximum continuous,maximum climb,maximum cruise and idle.The flight characteristics of a single-axis turbojet engine are described,including altitude characteristics and speed characteristics.According to the test data of the ground turbojet engine,the method of maximum likelihood and the ordinary least squares are used to carry out the logistic fitting of the thrust data of the micro turbojet engine.Through the fitting curve and the mean square error(Mse),it can be seen that the ordinary least squares is used to fit the thrust data of the ground turbojet engine.The curve can pass through most of the test data points with the good stability and convergence.(3)This paper introduces the generalized regression neural network and fuzzy least squares support vector machine into the modeling research of micro turbojet engine speed.And the model of turbojet engine speed are established respectively.Through the analysis of R-squared(R~2)and mean absolute percentage error(Mape),it is concluded that using fuzzy least squares support vector machine to establish models has higher accuracy,good generalization ability,and better model generalization ability.Based on this advantage,this paper selects fuzzy least square support vector machines to model the rotational speed of micro turbojet engines.The accuracy of the engine speed prediction model is verified through simulation,it provides a theoretical reference for the subsequent development of micro turbojet engines.