Research On Friction Heat Of Friction Based Electro-hydraulic Load Simulator

Friction based electro-hydraulic load simulator(EHLS)is a ground experimental device used to simulate the air torque of aircraft steering engine in the actual operation process.Compared with the physical experiments,it has the advantages of low experimental cost and high reliability.Because of the influence of structural problems Traditional EHLS always exist of extra torque load performance,and the friction based EHLS is improved in the structure,the traditional hydraulic motor load replace with friction disk load,to eliminate the extra torque in theory,which improve the load performance obviously,and meet the needs of rapid development of the aerospace industry,and is of great significance for the promotion of national defense strength.Different from the traditional EHLS,the friction based EHLS loads the steering engine through the friction torque generated by the relative rotation of a pair of friction disks.Although this will not produce extra torque in theory,but the friction disk will produce large amounts of friction heat in the process of loading,the friction heat in friction disks with large contact surface causes friction disk surface temperature rise sharply,which will affect the friction coefficient of the friction disk,and lead to the degradation of loading performance,so far as to reduce friction system life and damage the friction disk.In this paper,we analyzed the friction heating of friction based EHLS and proposed the structure of friction disc which can effectively improve the temperature rise.First,this paper analyzed the characteristics of friction disk loading process of sliding friction and heat transfer,and established the mathematical model of the friction disk according to the different kinds of thermal load.Then we analyzed the influence factors of friction heating,and analyzed the changing rule of the transient temperature field of friction disk surface through the establishment of the friction disk finite element model and the simulation software,to study the influence of surface temperature and loading torque fluctuation from different loading parameters and friction plate thickness.In addition,we studied the influence of the temprerature rise form the characteristics of friction disk material,providing theoretical basis for the friction disk material selection.Secondly,we studied thermoelastic instability phenomenon by the temperature rise of frition disk.the pressure perturbation model and temperature perturbation model of the friction disk was established by using the perturbation method and deduce the thermoelastic instability critical speed equation of the loading system.Then we analyzed the influence factors of the critical speed,studing the influence of different factors on the critical speed,and proposed method to relieve thermoelastic instability phenomenon.Finally,we studied the heat dissipation structure of friction disk by using CFD numerical analyzing method to solve the problem of temperature rise.Establishing the CFD model of friction disk,we compare the heat dissipation efficiency of heat dissipation disk and traditional disk by using simulation software.Then we designed two kinds of heat dissipation structure and analyzed the influence factors of them,which will provide theoretical basis to design the disk structure.In the same time,we studied the influence of air environment for heat dissipation property,and provide the studing basis for auxiliary heat dissipation system.