RE: Flow around lip seals

The centrifugal spinning force forces a tiny film into the sealing edge. the fluid draws the heat away.

Manufacturers literature often intimates this without giving away proprietary secrets, (like exact properties). Not necessary to CFD. good textbooks with tribology topics discuss/describe this, esp the slightly older ones.

-----Original Message-----
From: Steve McKenzie [mailto:mechproj@xtra.co.nz] Sent: Thursday, February 05, 2004 1:04 AM To: <a href="/group/PipingDesign/post?postID=1ebdMuLHn8rP4uyJAuw_op2NKSiB2-aMVn2CkREix1W1kPU-LmhzocallKqt8CivQsaEgUyAKXj8S_orVRXFJNdJ">PipingDesign@yahoogroups.com</a> Subject: [PipingDesign] Flow around lip seals

Gents
I have spent part of the day wondering about why lip (oil) seals dont run dry at the seal face and burn out. At first thought the rubber band action should squeeze the oil out of the sealing band. It was suggested that the seal taper on the oil side helps feed oil towards the sealing band. I have half convinced myself that this is true at low Reynolds numbers (due to viscous rotation) but would like some proof.
If it is true, then a rotating shaft running in a coned bearing should tend to pump oil out the small end of the cone. Provided the Reynolds number is low enough to stop centrifugal force throwing it the other way.
I could test it mathematically, but always seem to stuff up vector diagrams and the like.
Can it be done simply by CFD?
Is there any way I could CFD model this? Its only interest. In case you're uncertain, I am trying to bludge off someone to check this for free.
The independent variables would be diameter, speed, cone angle,clearance at outlet, density and viscosity. The output would be axial pumping rate and direction.
I have read the "state of the art" on the net, but the bottom line seems to be that the mechanism is unclear.

Cheers

Steve Received on Thu Feb 05 17:55:00 2004