| Yaw brake is the key to wind turbine accurate wind,ensure the efficiency of wind power generation,and realize the efficient and stable operation of the unit.Due to the complex contact state of the yaw brake during operation,the friction and wear of the brake system are affected,resulting in system instability and inducing vibration and noise,which affects the normal operation of the wind turbine.Therefore,it is of great significance to study the vibration and noise characteristics of yaw brake to reduce the noise level.Based on numerical simulation and experimental methods,the effects of complex operating conditions and groove structure on vibration and noise characteristics and wear behavior of yaw brake are studied from the tribological perspective.(1)The effects of elastic modulus,number of grooves and friction coefficient on yaw brake stability were analyzed through complex mode simulation,and the interval and distribution of system vibration instability were obtained.Using response surface method,the regression equations of different evaluation objectives were established and the optimal parameter intervals were determined.The results show that the unstable modes of the system are concentrated in [3kHz,6kHz],the real part of the unstable modes increases with the increase of the elastic modulus of the friction plate,the stability of the system is improved with the increase of the number of grooves,and the stability of the system is decreased with the increase of the friction coefficient.Based on response surface analysis,the optimal parameters are as follows: friction coefficient 0.32,elastic modulus interval [2.2GPa,2.4GPa],and the number of grooves is 3.(2)Based on the frequency range of unstable modes obtained from complex modal analysis,VIRTUAL LAB was used to establish the mapping relationship between structural grid and acoustic grid,and the radiated sound field during yaw braking was simulated.Based on orthogonal test method,the influence of yaw parameters on sound pressure was explored.The results show that the radiated sound pressure radiates from the center of the brake to the periphery in the vertical direction and decreases gradually in the horizontal direction.The yaw velocity has the greatest influence on the radiation pressure distribution of friction plate.(3)Conduct friction noise test on wind power yaw brake,explore the influence of different pressure,speed and groove structure parameters on vibration and noise characteristics of friction system,obtain acoustic and vibration signals under different influencing factors,analyze the correlation between brake parameters and groove texture on friction noise characteristics and surface friction characteristics combined with friction coefficient and wear morphology.The results show that the increase of braking pressure will intensify the adhesive wear of the brake disc and lead to the increase of the friction noise intensity of the disc.The wear morphology of friction plate is dominated by furrow.During the wear process,with the exposure of metal filler,the wear degree of friction plate increases with the increase of braking pressure,and the amplitude of friction noise increases.The friction noise amplitude of brake disc and friction plate increases with the increase of speed.The grooves texture can effectively reduce the noise of the brake disc and the friction plate in the friction process.The sound pressure and vibration signal amplitude decrease first and then increase with the increase of the spacing between the grooves of the brake disc,and the friction coefficient increases.With the increase of groove width,the noise intensity decreases first and then increases,and the friction coefficient decreases. |
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