微型动压气体止推轴承表面凹槽织构的参数优化

摘要

The axisymmetrical parabolic grooves are designed on the surface of thrust pad to im-prove the lubrication performance of micro aerodynamic thrust bearings.In order to maximize the load-carrying capacity,a hybrid optimization method is developed based on the multi-obj ective particle swarm search algorithm and sequential quadratic programming.In addition,the hybrid optimization method coupled with CFD code is used to implement geometry parametric optimiza-tion of parabolic grooves in micro aerodynamic thrust bearings.The influences of convergence ra-tio,width-to-diameter ratio,outlet height of gas film and velocity of rotor on the Pareto front are investigated.The relative depth,area ratio,untextured outlet length and the number of grooves on the pressure distribution and load-carrying capacity are also analyzed.Results show that the load-carrying capacity is an increasing function of width-to-diameter ratio and area ratio of groove.The load-carrying capacity is improved for the bearing with optimal parameters,with the improvement being more significant under the condition of small convergence ratio;the untex-tured outlet length and relative depth have a great influence on pressure distribution of the thrust bearing;there exists the optimal number of the grooves with the maximum load-carrying capaci-ty.%在推力盘表面织构加工出轴对称分布的抛物线凹槽，以改善微型动压气体止推轴承的润滑性能。为了获得最大的轴承承载力，针对试凑法耗时费力的特点，提出了基于粒子群多目标搜索和序列二次规划的混合优化方法，并结合CFD，对抛物线凹槽织构的参数进行了 Pareto优化。在此基础上分析了轴承收敛比、宽径比、气膜出口高度、速度对 Pareto优化解集的影响，研究了出口未织构率、相对凹槽深度、织构面积率和凹槽织构的数量等对轴承压力分布和承载力的影响。结果表明：承载力是宽径比和织构面积率的增函数；优化后的抛物线凹槽织构能够大幅提高轴承的承载力，尤其是在小收敛比范围内；出口未织构率和织构面积率对轴承的压力分布有较大影响；存在最优的凹槽织构数量使得轴承的承载力最大。