Journal Bearing Displacement

[417]

Hi, I'm try to measure the gap between a journal bearing and pressure while the shaft is rotating. I've install a pressure transducer inside the shaft to get the dynamic pressure. Do i need to take into consideration of the static pressure and how can i do it. I'm also looking at means to measure the minimun film thickness. Please provided me some guildance.

Regards,
Pat

 

[rhc]

Hi 417
When there is a true fluid film there will be a difference between the static and dynamic dimension in respect to the location of the journal relative to the bearing. When the pressure exerted via the journal is insufficient to displace the lubricating fluid the journal lifts and "skis" on the fluid. The mechanism here is that a fluid wedge is continuously forming and this provides new lubricant which is dragged between the sliding surfaces faster than it can be displaced. If there is no true fluid film then any difference will be neglible. Film thickness will vary significantly depending on the viscousity of the lubricating medium