Study On Friction-thermal-vibration Coupling Simulation For The Large-megawatt Wind Turbine Brakes

With the development of wind power technology,wind turbine has been studied.The brake disc/pad change has a very important influence on the stability and safety of braking.The actual work of the large megawatt wind power brakes is a complex coupling process including temperature field,stress field and vibration.In this study,based on the thermal-structure coupling establishing and studying the friction-thermal-vibration coupling model of large-megawatt wind turbine.The main researches are listed as follow:(1)According to the structure composition of large-megawatt wind turbine brakes and the vibration occurring in the braking process,calculating the natural frequency and load-displacement of brake spring and verify the form of vibration.Based on this,according to the law of energy conservation to analyzing the forces on the brake pad after vibration.Considering the actual size of the brake and the deformation in the braking process.Put forward the expression of vibration coupling force on the brake pad.(2)Based on the theories and methods of thermal-structure coupling and vibration coupling force and consideration of the effect of vibration during the braking process,establishing friction-thermal-vibration coupling for large-megawatt wind turbine.By comparing the results of friction-thermal-vibration coupling analysis and thermal-structure coupling analysis,concluding that the vibration aggravates the instability of the braking process.The correctness of the finite element model is verified by the comparison test results.(3)The initial braking pressure is chosen to be 13000N,17000N and 21000N by equal interval method.The initial speed of brake disc is 800rmp,1000rmp and 1200rmp respectively.The effect of different initial braking pressure and initial speed of brake disc on braking efficiency is analyzed.Researching results indicates the brake pad temperature field in the friction area is circular arc ring staircase distribution,and the maximum temperature appears at the entrance of the friction interface.The temperature in the circumferential direction of the brake disc friction area begins to decrease in the counterclockwise direction with the contact position of the brake disc and the brake pad.The temperature field is annular and has obvious temperature gradient in the radial direction.Compared with different working conditions,the results show that increasing the initial braking pressure will aggravate the uneven distribution of temperature field and stress field in brake pad and brake disc.Increasing the initial brake disc speed will make the distribution of temperature field and stress field of brake pad and brake disc even.In this study,the friction-thermal-vibration coupling analysis of the braking process for large-megawatt wind turbine.The coupling variation and distribution law of temperature distribution and thermal deformation of friction material.The analysis results provide a theoretical basis for the design of high performance wind turbine brakes.