The development and utilization of some equipment for low Reynolds number supersonic flow research

[摘要] NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.A low Reynolds number supersonic wind tunnel is a useful tool for the investigation of viscous effects in a high-speed flow. In order to avoid some of the difficulties inherent in a conventional wind tunnel system when operating at low Reynolds numbers, a two-phase cycle is proposed. By examining the thermodynamics of the wind tunnel the relative merits of two methods of operation -- the one-phase cycle and the two-phase cycle -- are compared, indicating certain advantages the two-phase cycle possesses over the conventional one-phase cycle when the tunnel is operated at high-speed and low Reynolds number. The design, construction and operation of a small (about 5 cm.[superscript 2] test section area) supersonic (M[.....]2) wind tunnel using a two-phase cycle with water (in liquid and vapor phases) as the working medium are described.Difficulties in pressure measurement and flow visualization, due to the nature of the working medium and the low density of the flow, are encountered. Means of meeting these difficulties are proposed, including a critical analysis of the schlieren technique, from which is evolved a workable arrangement for visualizing the low Reynolds number flow.As an example of the possible utilizations of the tunnel, the curvature, due to viscosity, of the attached shock wave on a wedge in uniform supersonic flow is investigated, using schlieren photography. The effective shape of the wedge is deduced from the shape of the shock wave, and is compared to theory with satisfactory qualitative agreement.

[发布机构] University:California Institute of Technology;Department:Engineering and Applied Science

[关键词] Aeronautics, Physics and Mathematics