Rarefied Gas Flow through a Pipe Orifice : Part II, Effects of an Orifice Plate of Finite Thickness

抄録

The flow characteristics of rarefied gas through a pipe orifice having an orifice plate of finite thickness is studied in the intermediate regime of rarefaction. The resistance and the pressure distribution are measured with emphasis on the effects of thickness of the orifice plate. The dependence of the overall conductance of the Knudsen number refers qualitatively to the case of a sharp edged pipe orifice which has been presented in Part I. As the flow approaches the free molecular limit, the conductance tends to a different constant value from Bureau's one. An improved formula to predict the overall conductance at the free molecular limit is proposed by the combination of conductances for a short tube and for a sharp edged pipe orifice. In the intermediate flow regime a method to estimate the overall conductance is also discussed, and an approximate formula for small pressure ratio is proposed comparing with the experimental results.