US 4,363,237 AGranted

Sound shield

AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration

InventorsTheodore R. Creel, Jr., Ivan E. Beckwith

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Abstract

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.degree. 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.

Claims5

Dependent claims

A noise shielding system for high speed transition research in supersonic and hypersonic wind tunnels provided with a source of supersonic or hypersonic fluid flow, a nozzle area through which the fluid flows, a test section for receiving the fluid flow and subjecting a test model positioned therein to the fluid flow and an exit area for the fluid flow, the improvement therewith comprising:

said test section being substantially a rectangular configuration;
a vacuum chamber surrounding each side of the test chamber and having conduits leading therefrom to a vacuum source;
a plurality of spaced individual rod elements forming the four sides of said test chamber thereby providing fluid communication between said test chamber and said vacuum chamber;
one end of each said spaced rod elements terminating and merging with a faired entrance shield portion of said vacuum chamber at the end of said test chamber receiving the fluid flow;
the other end of each said rod element terminating and merging with a rectangular passageway leading to the wind tunnel exit;
said rod elements and said entrance shield portion being slightly inclined inwardly toward the downstream end of said test chamber to provide a taper and slightly reduced cross-section dimensions to said test chamber at the exit end thereof.

3 more elements

Dependencies are inferred from the claim text.