Experimental Investigation of Hydrodynamic Self-Acting Gas Bearings at High Knudsen Numbers.
Abstract
This investigation gives experimental confirmation of the 'slip flow' theory, developed by Burgdorfer, for modelling hydrodynamic gas bearing with clearances below 0.25 micrometers. An interferometric technique using two CW lasers is used to measure the small clearances with an 0.025 micrometers accuracy. The pitch and roll angles of the slider bearing and the surface contour of the slider are also measured interferometrically. The effects of molecular rarefaction are studied by operating the bearing in different gas media with different mean free paths. Air is used to study Knudsen number below 0.5 while helium is used to study Knudsen number above 0.5. Experimentally measured trailing edge clearances and pitch angles are compared with theoretical predictions using the 'modified' Reynolds equation with velocity slip boundary conditions. The modified Reynolds equation is solved numerically using two different numerical algorithms. Excellent agreement between experiment and theory is found for clearances as high as 1.60 micrometers to as low as 0.075 micrometers with corresponding ambient Knudsen number of 0.04 and 2.51, respectively. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1980
- Accession Number
- ADA087400
Entities
People
- Gerald A. Domoto
- Yiao-tee Hsia
Organizations
- Columbia University