1990 Fiscal Year Final Research Report Summary
Effect of Surface Roughness on the Rarefied Gas Internal Flow
Project/Area Number |
01550134
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Research Category |
Grant-in-Aid for General Scientific Research (C)
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Allocation Type | Single-year Grants |
Research Field |
Fluid engineering
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Research Institution | Akita University |
Principal Investigator |
SAWADA Tadashi Akita University, Mining College, Professor, 鉱山学部, 教授 (40087466)
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Project Period (FY) |
1989 – 1990
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Keywords | Rarefied gas / Internal flow / Slip flow / Free molecule flow / Conductance / Surface roughness / Specular reflection / Back scattering |
Research Abstract |
The flow passages were constructed of two flat plates so that the surface roughness could be controlled at arbitrary values and the conductances from viscous to free molecule conditions were measured. Combining linearly Knudsen's formula for free molecule flow and Navier-Stokes equation, the equation which could be applied for all the pressure ranges was derived. The free molecule flow conductance also was calculated by the kinetic theory of gases. The results are summarized as follows : 1. The conductances of polished glass, electro chemical buffed aluminum and stainless steel with the centerline average roughness of 0.004-0.040 mum are larger by 20% than ones of ground glass and rolled aluminum with centerline average roughness of 0.50-1.04 mum. 2. The materials of the passages make little difference in conductance. 3. The measured conductances agree with the values of the combined equation of Knudsen's and Navier-Stokes's over all the pressure ranges, but in the free molecule flow region, they are one second the other existing theoretical values. 4. The free molecule flow conductance calculated on the assumption of the diffuse reflection on the wall agrees well with the measured one of polished glass, electrochemical buffed aluminum and stainless steel passages. This suggests that the back scattering may take place in rolled aluminum and ground glass passages.
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Research Products
(2 results)