纳米粒子气膜承载能力研究

Study on Load Capacity of Nanoparticles-laden Gas Film

利用自行研制的纳米粒子气膜承载能力测试平台,将粒径30 nm的SiO2球形纳米粒子添加到气体推力轴承中形成45μm厚纳米粒子气膜,研究不同纳米粒子体积分数对气膜承载能力的增强效果与作用机理。通过测试纳米粒子添加前后气膜承载能力和压力的变化与气膜厚度间的关系研究纳米粒子体积分数对承载能力的影响规律。结果发现,纳米粒子气膜的承载能力随着纳米粒子体积分数的增加而逐渐增加,在纳米粒子体积分数约为0.04%时,承载能力的增加幅度最大约为20%。纳米粒子体积分数进一步增加时承载能力增加幅度开始减小。为理解这一变化规律以及纳米粒子气膜对承载能力的增强机理,使用考虑纳米粒子气膜中气体和粒子相互作用的流体力学方程计算纳米粒子气膜中的压力分布。通过计算结果与试验数据的对比,验证纳米粒子体积分数对承载能力的影响规律。提出并证实纳米粒子对气膜承载能力的增强作用,纳米粒子气膜承载能力研究结果对纳米粒子气膜润滑新型转子轴承系统的设计具有工程意义。

Nanoparticles of 30 ftm in diameter are added into a gas thrust bearing, in which the film thickness is 45 ~m. Then, a nanoparticles-laden gas film with different nanoparticles volume fraction is formed. The enhancement effect of nanoparticles on gas film load capacity is studied with a self-developed experimental apparatus and the mechanism of this phenomenon is discussed. The load capacity and film pressure before and after adding nanoparticles, which varies with the film thickness, are measured. The variation tendency of load capacity with nanopartieles volume fraction is derived. It is found that the load capacity increases with the increase of nanopartieles volume fraction. When the nanoparticles volume fraction is about 0.04%, the increment of load capacity reaches about 20%. Then, the increment of load capacity decreases gradually. For understanding the variation and the mechanism of load capacity enhancement effects by nanoparticles, fluid mechanics equations that considered gas and nanoparticles interaction are employed to calculate the film pressure distributions. By comparing the numerical and the experimental results, the variations of load capacity with nanoparticles volume fraction are verified. The study proves that nanoparticles has an enhancement effect on gas film load capacity for the first time. Besides, the finding provides an engineering guidance for the design of novel nanoparticles-laden gas film rotor-bearing system.