Expertise Facility Types

Research tagged "airframe noise"

Effects of Distributed Source Coherence on the Response of Phased Acoustic Arrays

Phased acoustic arrays have been used successfully to locate propulsive and nonpropulsive aeroacoustic sources with the array located both in a moving wind-tunnel stream and in still air. Multiple or distributed sources may vary over the full range in coherence level, particularly when local reflections are present. A constant contour level integration boundary is defined […]...
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Effect of Surface Treatment on Array Microphone Self-noise

A method for reducing the flow-induced self-noise of acoustic array microphones was demonstrated in a wind tunnel. Unsteady boundary-layer flow in the wind tunnel induces large pressure fluctuations on exposed, flush-mounted microphone diaphragms, reducing the signal-to-noise capability of microphone arrays. Two important steps were take to reduce this background noise. First, the microphones were recessed […]...
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