TourTourAerostatic collar bearing fed through simple orifice restrictors
 Diameter 2R0 (outer diameter bearing)   10-3 m
 Diameter 2R1 (center of groove)   10-3 m
 Diameter 2R2 (inner diameter collar bearing)   10-3 m
 Groove width δ   10-3 m
 Groove depth h2   10-3 m
 Film thickness h0   10-6 m
 Supply pressure pS   106 Pa
 Ambient pressure pA   106 Pa
 Pressure factor β  
 Coefficient of discharge Cd  
 Number of orifices  
 Pressure ratio pR/pS  
 Annulus area Ac  
 Flow rate M   10-6 kg/s
 Flow ratio M1/M2  
 Diameter orifices d   10-3 m
 Load capacity F   N
 Stiffness S=-dF/dh   106 N/m
 Flow rate Q   l/min

h0: A high axial bearing stiffness, self-aligning capability and the minimal flow is obtained with small film thickness. The minimal value of the film thickness is limited by bearing deflections and flatness of the bearing surface and is usually related to the bearing size.

δ, h2: The volume of the pocket must be as small as possible to make the bearing less sensitive to instability. The pocket however is needed to get a smooth pressure distribution in the circumference and secondly to realize simple orifice compensation. The pressure distribution in the groove is assumed to be homogenous which is a good approximation for a large groove depth. Numerical calculations are required to calculate the effect of the pressure drop in shallow grooves.

Ac: The restrictor can become inherent with shallow grooves and Ac must therefore be checked. The pressure drop over passage A1 of the simple orifice restrictor is more than four times higher than that over the annulus area A2 when Ac>1 (Fig 12.2 of the book).