Influence of the Spacing of the Partially Porous Aerostatic Journal Bearings and the Rotating Speed on Performance of the Spindle

The influence of the spacing of the partially porous aerostatic journal bearings and the rotating speed of the spindle on the pressure distribution in the bearing gap and the housing gap were studied. Based on the finite volume method and the pressure-velocity coupling scheme of the SIMPLE algorithm with the standard k-ε turbulent model, A CFD software was used to solve the Navier-Stokes equations to figure out the pressure in the bearing gap and the housing gap. The computed results indicated that when the spacing of the bearings between air outlets was increased, the pressure got higher not only in the bearing gap, but also in the housing gap. The load carrying capacity of the bearings and the stiffness of the spindle could be improved. If the spacing of bearings was reduced by adding one more bearing to the location between the original bearings, the pressure in the narrower housing gap would decrease, while that in the wider housing gap would increase. Though the extra bearing could not help increase the net pressure exerted on the spindle effectively, it did help redistribute the housing gap pressure so that the pressure difference in the air gap could be reduced and the spindle was able to rotate stably.