| 摘要 |
A noise attenuation device for use in a jet engine test cell for testing a jet engine comprising a carbon steel pipe which is aligned axially with direction of exhaust from the jet engine. The carbon steel pipe is positioned within an augmenter within the test cell. Cold air enters the front end of the carbon-steel pipe. Adding three times the mass of cold air to that of the hot jet exhaust allows the hot jet exhaust to mix with the cold air forming an engine exhaust-cool air mixture. When the engine exhaust-cool air mixture reaches the outlet end of the carbon steel pipe, its temperature is reduced from 3800° F. to less than 1200° F., which substantially reduces noise generated by the jet exhaust. Located in proximity to the rear end of the carbon steel pipe is an annular region which is formed between perforated side plates within the carbon steel pipe and the inner wall of the augmenter. The flow is diffused as the flow area expands in the annular region. The combination of the carbon steel pipe and the annular region slow the velocity of the jet engine exhaust-cool air mixture, further reducing noise production from the jet engine.
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