Simulation Of Flow Field In Micro Engine Turbine

III Rotor is the core component of many rotating machinery,and its safe operation directly affects the normal use of turbine and other equipment.With the development of micro electro mechanical system(MEMS)technology,the miniaturization of engine becomes a trend.The micro engine has the characteristics of small structure,high speed and light weight.As the rotating machinery working speed increasing,vibration induced by gas flow is also growing,leading to airflow induced problems are more serious.Once the impeller instability,the turbine rotor system will eventually affect the safe operation.This paper focuses on the research of frequency domain characteristics of internal flow field in rotor system under the action of Alford force and rotor unbalance.Work as follows:Firstly,the system motion model of Alford force and rotor unbalance is established,and the stability analysis of rotor system is carried out.To solve the motion equation of numerical simulation by using Runge-Kutta method,frequency domain rendering system diagram,the trajectory,and then analyze the impact of eccentricity,speed of system characteristics.By using the optimized formula of exciting force,the influence of inlet angle and fluid density on the exciting force is analyzed.Second,based on the axis orbit diagram of 2D flow field,and the simulation of rotor system using FLUENT.According to different speed,different mass flow,turbine rotor static eccentricity and dynamic analysis of the changes of the flow field in eccentric under various conditions Analysis and calculation of two-dimensional turbine rotor of the unsteady flow field,and different time to obtain the force curve of the turbine rotor Through the analysis of aerodynamic parameters nephogram and time-domain curve,to illustrate the different eccentricity and operation conditions,effects of rotor eccentricity on the turbine rotor and the aerodynamic performance of the internal flowThird,based on CFD simulation results,the influence of Alford force and rotor imbalance is analyzed from time domain and frequency domain in two aspects.Based on the simulation results of the inner flow field,the force of the blade in the rotor is obtained,and the periodicity of the force signal is discussed.By the fast Fourier transform,convert the force signal to the frequency domain to obtain the force signal spectrum analysis,the frequency characteristics of flow field in the unbalanced excitation force of rotor,under such circumstances,using the simulation method to verify the rotor imbalance fault characteristic frequency.The results show that:(1)the model of static eccentricity,the rotational speed of the turbine is greater,the greater the amount of eccentricity and mass flow increases,the greater the flow induced force;(2)in the computer under the condition of limited resources,select static eccentric model to calculate,calculation of high precision can be used to move eccentric model calculation;(3)effects of eccentric force on the blade is mainly concentrated in the vicinity of the fundamental frequency,stress amplitude should be reasonable control at the basic frequency,to avoid blade fatigue damage.