Sound shield

摘要

An improved test section 16 for a supersonic or hypersonic wind tunnel 10 is disclosed wherein the model tested is shielded from the noise normally radiated by the turbulent tunnel wall boundary layer. A vacuum plenum 23 surrounds spaced rod elements 28 making up test chamber 16 to extract some of the boundary layer as formed along the rod elements during a test to thereby delay the tendency of the rod boundary layers to become turbulent. Novel rod construction involves bending each rod slightly prior to machining the bent area to provide a flat segment 29 on each rod for connection with the flat entrance fairing 31. Rods 28 and fairing 31 are secured to provide a test chamber incline on the order of 1 DEG outward from the noise shield centerline to produce up to a 65% reduction of the root-mean-square (rms) pressure over previously employed wind tunnel test sections at equivalent Reynolds numbers.