狭缝节流空气静压轴承局部气膜流场的直接数值模拟

采用3阶精度的迎风格式及2阶精度的中心差分格式,直接求解二维非定常N-S方程组,研究狭缝节流空气静压轴承压降恢复之后区域的流场特性。使用雷诺方程计算相同位置气膜中心处的流场状态,并与直接数值模拟方法的计算结果进行对比。结果表明:雷诺方程与N-S方程在计算域内计算结果基本一致,两者压力偏差为0.173%,速度偏差为1.217%;流场压力、密度沿气流方向逐渐减小,但在气膜方向几乎不变;流场速度、压力梯度沿气流方向逐渐增加,速度在流场出口处达到最大值;直接数值模拟方法得到了流场的温度变化,即整个流场的温度变化很小,温度整体呈上下高、中心低的分布,而雷诺方程无法计算得出整个流场的温度变化情况;采用雷诺方程计算轴承压降恢复之后区域的流场是合理的。

Direct Numerical Simulation of Local Gas Film Flow Field in Slot-restricted Aerostatic Bearing

A 3rd-order precision upwind scheme and a 2nd-order precision central difference scheme were adopted to directly solve two-dimensional unsteady N-S equations,and to study the flow field characteristics of the region after pres- sure drop recovery of aerostatic bearing with slot-restricted. The flow field state of gas film center at the same position was calculated by using the Reynolds equation and was compared with the calculation results of the direct numerical simulation method. The results show that calculation results of Reynolds equation and N-S equation are basically the same in the com- putational domain,with the pressure deviation of 0. 173% and the velocity deviation of 1. 217%. The flow field pressure and its density are gradually decreased along the direction of gas flow,but it is almost unchanged in the direction of gas film thickness. The speed of flow field and pressure gradient are gradually increased along the direction of gas flow,and the speed reaches a maximum at the outlet of flow field. The temperature change in the flow field was obtained by the direct simulation method,that is the temperature change in the flow field is very little,and the overall temperature is higher on the upper and lower wall and lower in the center. While the temperature change in the flow field cannot be calculated by Reyn- olds equatio