基于分离变量算法的静压止推气体轴承节流孔特性研究

Orifice characteristics of aerostatic thrust bearing based on MSV

首先基于分离变量算法(method of separation of variables, MSV)求解了单节流孔静压气体轴承的层流边界层方程,研究了节流孔附近流场特性,阐明了节流孔出口附近压降现象是由于惯性效应导致,并研究了轴承几何参数和供气参数对压降现象的影响规律。最终提出了压降现象产生的临界条件为压比为0.940 9,也即压比大于临界压比时,压降现象消失。其次基于质量流量相等原则,结合层流边界层的MSV方法及雷诺方程的解析算法,提出了一种计算节流孔系数的新方法,并研究了轴承的几何参数及供气参数对节流孔系数的影响规律。结果显示,节流孔系数存在着参数敏感和不敏感区域,这是由于当压比小于等于0.6左右时,节流孔系数趋近于一个常数0.86左右。

Here,firstly,laminar flow boundary-layer equation of a single-orifice static pressure gas bearing was solved based on the method of separation of variables(MSV)to study flow field characteristics near orifice.It was clarified that pressure depression near orifice outlet is caused by inertia effect.Then,influence laws of bearing geometric parameters and gas supply parameters on pressure depression were analyzed.Finally,the critical condition of the pressure ratio reaching 0.9409 for the occurrence of pressure depression was proposed,it was called the critical pressure ratio.It was shown that when gas pressure ratio is larger than the critical pressure ratio,pressure depression disappears.Secondly,based on the principle of equal mass flow rate,combined with MSV for laminar flow boundary-layer and the analytical algorithm of Reynolds equation,a new method for calculating discharge coefficient was proposed,and effects of bearing geometric parameters and gas supply parameters on discharge coefficient were studied.The results showed that discharge coefficient has parameter insensitive and parameter sensitive regions,it is due to discharge coefficient approaching a constant of around 0.86 if pressure ratio being less than or equal to around 0.6.