Asymptotic behavior of high-Reynolds-number flow through an array of blunt bodies

1993 ◽  
Vol 36 (4) ◽  
pp. 308-325
Author(s):  
S. I. Chernyshenko

This paper examines the theory of the unsteady motion caused by fluctuations in the driving pressure of a high Reynolds number mean flow through a circular aperture in a thin rigid plate. A theoretical model is proposed which is amenable to exact analytical treatment, and involves the shedding of vorticity from the rim of the aperture. The theory determines the dependence of the Rayleigh conductivity of the aperture on the Strouhal number, and provides quantitative estimates for the rate of dissipation of large scale ordered structures as a result of the generation of turbulence at the apertures in a perforated liner. The limit of zero Strouhal number yields a description of steady high Reynolds number flow, the contraction ratio of the emerging jet being predicted to be equal to the minimum theoretical value of ½. Application is made to the problem of sound trans­mission through a uniformly perforated screen in the presence of a low Mach number bias flow.


1995 ◽  
Vol 2 (1) ◽  
pp. 23-32
Author(s):  
Tsutomu adachi

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, LN consumptions was attained. It was with Mach-number independent of each other, o 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.


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