The flow of a rarefied gas through a circular orifice and a two-dimensional slit

Citation

Thach, Nathan Raymond (1969) The flow of a rarefied gas through a circular orifice and a two-dimensional slit. Engineer's thesis, California Institute of Technology. doi:10.7907/B8GW-KD14. https://resolver.caltech.edu/CaltechETD:etd-12162005-104414

Abstract

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Experiments were conducted to measure the mass flow of helium through a circular orifice and a two-dimensional slit over a wide range of Reynolds number for large pressure ratios across the test apertures. The Reynolds number, defined as [...] for the orifice and [...] for the slit, ranged nominally from 5 x [...] to 3 x [...]. The upstream-to-downstream pressure ratio, [...], was at all times greater than 100:1 so that the Mach number, defined as [...], was at all times approximately unity.

The results of the present experiments on the circular orifice are found to compare favorably with the results of experimental and theoretical work on the circular orifice by previous investigators. The results of the present experiments on the two-dimensional slit (which appear to be the first of this nature) do not compare favorably with the results of the meager amount of theoretical work on the two-dimensional slit.

The transition from free-molecule flow to continuum-limit flow for the circular orifice appears to be substantially complete within the range [...]. The two-dimensional slit behaves very much like the circular orifice for [...]. Unlike the circular orifice, however, the transition from free-molecule flow to continuum-limit flow for the two-dimensional slit appears to cover the range [...].

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