平面静压气浮轴承超音速流场的研究

Supersonic velocity field of externally pressurized gas-lubricated circular bearings

为了全面快速进行平面气浮轴承超音速流场的计算分析,对原有的简化建模方法进行了改进和完善.建立了包括供气孔在内的完整轴承流道,依据壅塞状态时轴承质量流量不变的条件,推导出流道各部分气流速度、马赫数、雷诺数和压力分布的计算公式.计算结果表明,激波位置、马赫数、雷诺数和气膜内压力与供气压力、气膜间隙、供气孔径大小有关.通过与实际的测试结果相比可以发现,随着供气压力的增大,采用改进后的简化模型的方法得到的压力与实验测试结果基本一致,而且简化模型得到的最大恢复压力位置与实验结果也基本一致,可从本质上反映出流场内受力状态.但由于简化模型将进气孔处的激波假设为正激波,忽略了气体粘性,导致求解的压力最小值与实测值误差较大.

In order to carry out an overall rapid calculation and analysis on supersonic gas bearings flow field, the original simplified model was greatly improved. The flow passage of externally pressurized gas thrust bearing with central supply hole was built. Based on the fixed flow rate under the choke condition, calculation formulas were derived for flow velocity, Math number, Reynolds number and press distribution in the flow passage to calculate the flow field. The result presents that, shock wave position, flow velocity, Math number and Reynolds number are related to the supply press, the bearing clearance and the diameter of supply hole. Compared with experimental results, it is found that, with the increase of supply press, the press force and the maximum raising press position obtained by the improved simplified model are basically consistent with experimental results, and the stress in the flow field can be reflected in essence. However, the shock wave at the entrance in the simplified model is assumed as the normal shock and gas viscousness is neglected, so the calculated minimum press deviates widely from the experimental result.