Accession Number : AD0265547

Title :   PRESSURE PROBES IN FREE MOLECULE FLOW

Corporate Author : TORONTO UNIV (ONTARIO) INST FOR AEROSPACE STUDIES

Personal Author(s) : ENKENHUS,K.R. ; HARRIS,E.L. ; PATTERSON,G.N.

Report Date : JUL 1961

Pagination or Media Count : 1

Abstract : When the mean free path becomes a significant fraction of a characteristic dimension of a pressure probe, the usual continuum formulae relating the measured pressure to the free-stream pressure and Mach number are no longer valid. The case where the mean free path is so large compared with the probe diameter that intermolecular collisions may be neglected is treated. This is the condition for free molecule flow. Theoretical expressions are given for the pressure measured in a flowing gas with an orifice probe and a long-tube pressure probe. Experimental investigations were conducted using a low-density wind tunnel and a rotating-arm apparatus. Agreement between theory and experiment was quite satisfactory. Although this work was done primarily in connection with the flow of low density gases over models in the laboratory, the results are equally applicable to situations encountered in upper atmospheric research. (Author)

Descriptors :   *RAREFIED GAS DYNAMICS, DIFFUSION, EXPERIMENTAL DATA, GAS FLOW, KINETIC THEORY, ORIFICES, PITOT TUBES, PRESSURE, SHEETS, STATISTICAL FUNCTIONS, VELOCITY, WIND TUNNEL MODELS

Distribution Statement : APPROVED FOR PUBLIC RELEASE