1996-02-01

Elimination of a High-Frequency Narrow-Band Noise Component in a Low-Noise Automobile Wind Tunnel 960904

ABSTACTThe out-of-flow background noise spectrum in the test section of the full-scale low-noise automobile wind tunnel facility of BMW Technik GmbH in Munich showed a pronounced hump around 2 kHz Although this excess noise component was audible, it did not interfere with the automobile flow noise studies conducted in the tunnel An experimental study was performed to identify the source mechanism. It was found that the excess noise is generated by small cavities in the face side of the impeller blade tips When the cavities were closed the excess noise component completely dissappered The peak spectral level of the fan noise was reduced by as much as 30 dB The overall out-of-flow level reduction in the test section was 3 dB(A).

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: Purchase more aerospace standards and aerospace material specifications and save! AeroPaks off a customized subscription plan that lets you pay for just the documents that you need, when you need them.
X