Averaged Reynolds Equation Extended to Gas Lubrication Possessing Surface Roughness in the Slip Flow Regime: Approximate Method and Confirmation Experiments

[+] Author and Article Information
Y. Mitsuya, H. Ota

Department of Mechanical Engineering, School of Engineering, Nagoya University, Nagoya 464, Japan

T. Ohkubo

Magnetic Storage Group, NTT Electrical Communications Laboratories, Nippon Telegraph and Telephone Corp., Musashino, Tokyo 180, Japan

J. Tribol 111(3), 495-503 (Jul 01, 1989) (9 pages) doi:10.1115/1.3261957 History: Received March 05, 1988; Online October 29, 2009


The average film thickness theory is extended to gas lubrication possessing surface roughness in the slip flow regime. A simplified averaged Reynolds equation is derived and its applicability is confirmed through comparing with experiments. This averaging equation makes use of the mixed average film thickness defined as Have m = αHm + (1 − α)Hmˆ, where m = 1, 2 and 3; α indicates the mixing ratio; and H̄ and Ĥ denote the arithmetically and harmonically averaged film thicknesses. The experiments were performed using computer flying heads having precisely photolithography-fabricated longitudinal, transverse or checkered pattern roughnesses under submicron spacing conditions. From the excellent agreement obtained between the calculated and experimental results, it can be concluded that the assumption that velocity slippage occurs along the surface even if roughnes is present is justified, and that the approximate method is applicable for determining the surface roughness effects in the slip flow regime.

Copyright © 1989 by ASME
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