GB836385A - Wind tunnel - Google Patents

Abstract

836,385. Wind tunnels. METALLBAU SEMLER G.m.b.H. Jan. 13, 1958 [Jan. 15, 1957 ; March 22, 1957], No. 1193/58. Class 4. A wind tunnel comprises means producing a main gas stream in the test section, and, surrounding the main stream, at least one auxiliary tubular gas stream flowing in the same direction as, but at a lower velocity than the main gas stream. In the figure, a compressor delivers gas to the tunnel inlet nozzle 1, comprising a fixed wall 2 and a movable flexible wall 3, one end of which is anchored to a flap 4 pivotable about axis 7 by an hydraulic jack 7, and the other end of which is attached to a hydraulic jack 10 maintaining the wall under tension. The wall rests on a shaped member 5 movable by an hydraulic jack 8 connected to a lever pivoted to member 5 and to fixed structure at 6. The flow characteristics of the inlet nozzle may thus be adjusted. At the inlet to the test section 15, an annular chamber fed with gas under pressure from a duct B, surrounds the outlet of nozzle 1, and produces a tubular gas stream flowing along the walls 12 of the section, and into an annular collecting chamber 16 discharging into a duct C. The velocity of the tubular stream is half that of the main flow, whereby turbulance is reduced to a minimum. There may be a plurality of tubular streams, their velocities decreasing in radially outwards sequence. The divergence of walls 12 is adjustable by hydraulic jacks 14. The diffusor section 17 comprises a fixed wall 18 and a movable flexible wall 19 which is anchored at the diffusor inlet end and maintained under tension by connection to an hydraulic jack 26 at its downstream end. The wall rests on a shaped member 20 movable by a hydraulic jack 21. The diffuser characteristics may thus beadjusted, and may be adjusted simultaneously with the inlet nozzle characteristics. Apertures 22 provided in walls 18 and 19 are used for injecting gas into or withdrawing gas from the diffuser. The diffuser has a right angled bend at 23, and adjustable apertures are provided at 24 for the withdrawal of hot exhaust gases from rested jet engines. A pressure sensitive device is provided upstream of the inlet to nozzle 1 to adjust automatically the orientation of the compresser stator vanes, to keep the gas stream pressure constant. Mechanical, pneumatic, or electrical devices may be substituted for the hydraulic jacks.