Abstract
In this paper, first, the principle, structures, operations, and performances of the cryogenic wind tunnel are described. By changing the pressure, temperature and velocity of gas a high Reynolds number flow (5 × 104 < Re < 107) can be obtained. From the research results, a high Reynolds number flow with comparatively low power, LN2 consumptions was attained. It was with Mach number independent of each other.To show some examples of high Reynolds number flow, the effects of surface roughness and grooves on the surface of a cylinder on the flow are measured using models with various values of roughness and size. A model test of an airship was also conducted. With the high Reynolds number flow, the thickness of the boundary layer becomes thinner. Then the surface conditions of a body have great effect on the flow phenomena and on the drag of the body. Some attempts to reduce the drag of the body were shown.
Highlights
In this paper, first, the principle, structures, operations, and performances of the cryogenic wind tunnel are described
Number at the critical point, i.e., Re(Camin with
For a cylinder with a larger surface roughness than (Ks/d)rit, the Reynolds number at the critical point became smaller with an increase in (Ks/d )
Summary
Faculty of Engineering, Osaka Sangyo University, 3-1-1, Nakagaito, Daito, Osaka, Japan(574). A high Reynolds number flow with comparatively low power, LNz consumptions was attained. It was with Mach number independent of each other. With the high Reynolds number flow, the thickness of the boundary layer becomes thinner. Some attempts to reduce the drag of the body were shown. In order to make it stay at one point, the drag on the body must be small. The flow around the body are high Reynolds and low Mach number flows. It was shown that its drag can be made smaller if suction is applied to the boundary layer
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