Improvements in supersonic wind-tunnels for a variable mach number

摘要

783,046. Wind tunnels. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. Dec. 15, 1955 [Dec. 20, 1954], No. 36050/55. Class 4. A supersonic wind tunnel comprises one or more nozzles disposed at the throat upstream of the working section, to provide an auxiliary variable jet of gas to restrict the effective crosssection of the throat, enabling various Mach numbers to be obtained in the working section. In Fig. 2, two slots 10 are provided in the walls adjacent the throat 3 of a rectangular wind tunnel with a working section 4. Two cylinders 11 close these slots, and their hollow interiors are connected with a source of gas under high relative pressure, e.g. the wind tunnel compresser, an auxiliary compresser, or the atmosphere in the case of a suction operated tunnel. The gas issues from slots 7, which can be varied in direction by levers 12, interconnected to move equally and oppositely by a rack and pinion gear, Fig. 3 (not shown). A turnbuckle is provided in the linkage for datum shift of one lever. In Fig. 4, the gas is supplied through a valve 8 to three nozzles 7a, 7b and 7c, of which the first may be the largest, having different inclinations to the tunnel axis. A suction orifice 22 is controlled by a valve 23, to cause the flow to adhere to the tunnel wall. A further injection orifice 20 is supplied through a valve 21 and pipe 24 from a tapping point in the tunnel at a region of higher static pressure. This orifice is so inclined as to energize the boundary layer in the tunnel.