Pressure probes in free molecule flow

Title

Pressure probes in free molecule flow

 Author

Enkenhus, K.R.
Harris, E.L.
Patterson, G.N.

Institution

University of Toronto Institute of Aerophysics

 Date

1961-07-01

 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probe, the usual continuum formulae relating the measured pressure to the free-stream pressure and Mach number are no longer valid.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 present paper treats the case where the mean free path is so large compared with the probe diameter that intermolecular collisions may be neglected. 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 have been conducted using a low-density wind tunnel and a rotating-arm apparatus. Agreement between theory and experiment was quite satisfactory. Although the reported work was do ne 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.

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 Publisher

University of Toronto

 Source

UTIA Review, No. 19

 Part of collection

Aerospace Engineering Reports

 Document type

report

 Rights

(c)1961 University of Toronto
Files
PDF 019.pdf 14.16 MB
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