PRESSURE MEASUREMENT IN TRANSITION AND FREE MOLECULAR FLOWS USING ORIFICE PROBES,
Abstract
When bodies travel in a gas so rarefied that the mean-free-path of the molecules is much larger than any of the dimensions of the body the aerodynamic properties of the body can be calcu lated using kinetic theory ignoring the collision between the molecules that have struck the body and those directed towards it. At slightly higher densities such collisions start to become of importance and deviations from the freemolecular theoretical results will occur. A series of experiments, performed in a rotating arm apparatus to study the deviations from freemolecular flow that occur at low subsonic speeds, are described. The specific criterion used in these tests was the pressure measured by an orifice probe in the walls of cylinders and flat plates of rectangular and circular shape which were perpendicular to the flow direction. It was found that the deviations from free-molecular flow depend on both dimensions perpendicular to the flow in relation to the mean-free-path and on the speed ratio. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1963
- Accession Number
- AD0428157
Entities
People
- J. C. Lafrance
Organizations
- University of Toronto