AN EXPERIMENTAL INVESTIGATION OF FREE MOLECULE MOMENTUM TRANSFER BETWEEN GASES AND METALLIC SURFACES
Abstract
Measurements of the normal momentum transfer between gases and metallic surfaces were obtained under conditions of free molecule flow by means of a torsion balance and molecular beam apparatus. Helium, hydrogen, neon, nitrogen, argon, and carbon dioxide were investigated on tungsten, platinum- blackened-tungsten, platinum, and aluminum surfaces which were most likely contaminated with oxides and absorbed gases. In the majority of the tests a thermal beam of gas molecules was directed against a heated test surface at normal incidence; a small number of tests were performed at oblique angles of incidences. Momentum transfer measurements were obtained with the surface at various temperatures, the range being from 25 to 550 C. The efficiency of the momentum transfer process increases with the molecular weight of the test gas and the roughness of the test surface, but is relatively independent of the surface material under the present conditions. The momentum transfer rates for helium and hydrogen are significantly less than for the heavier gases. The accommodation to the surface temperature is incomplete except, possibly, for argon and carbon dioxide. he results were used to estimate the values of the coefficient of translational energy transfer and a modified form of the coefficient of normal momentum transfer.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 25, 1962
- Accession Number
- AD0273495
Entities
People
- Robert Erwin Stickney
Organizations
- University of California, Berkeley