平面静压气浮轴承的超声速流场特性

Characteristics of Subsonic Velocity Field of Externally Pressurized Gas Thrust Bearings

为研究轴承流场大间隙时激波的形态和激波与边界层的相互作用,建立供气孔和轴承间隙组成的完整气体轴承流场,采用层流和分段湍流模式计算大间隙下平面气浮轴承的流场特性,计算与试验测试结果基本吻合。计算结果较好模拟出轴承间隙内由激波/边界层干扰诱导的复杂流场的流场特性,再现不同间隙下流场中的激波结构和激波对流场的影响。从速度和压力的分析中可以看出,随着供气压力和气膜厚度的增加,进气孔转角处流速增大,产生局部回流,喉口过后可能出现超声速,在间隙相对较小时,粘性的影响大,超声速流通过压缩波时压力缓慢回升,速度降为亚声速;当间隙增大到一定程度,流场内形成斜激波和激波串,气流通过激波时压力突变。

The complete gas field including supply hole and clearance is built up, and a two-dimensional laminar flow model and local turbulent flow model are used to calculate the parameters of gas thrust bearing in different clearances. The calculation results basically agree with the experimental results. The numerical results illustrate the shock/boundary layer interaction and the shock train phenomenon. The analysis of velocity and pressure show that, with increase of both gas supply pressure and clearance thickness, the gas flows more quickly at the entrance of supply hole, which produces local back-flow, there is supersonic flow behind the throat, and pressure rise slowly with the dissipation effect at wall and oblique shock wave, the gas lowers down to subsonic velocity, gradually shows non-viscosity.