Active Control of Flow Induced Resonance in Continuous Corrugated Tubes
Final technical rept. 1 Jul-30 Sep 92,
CALIFORNIA UNIV SAN DIEGO LA JOLLA OFFICE OF CONTRACT AND GRANT ADMINISTRATION
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Wind tunnel experiments were conducted to study sound generation from corrugate tubes. Hot-wire and microphone measurements were used to determine the response of the following tube geometries to flow excitation fully corrugated tube, tube with two corrugations, tube with one corrugation only, and tube with no corrugations at all. For the tube with at least two bumps, it was found that the acoustic output peaks when there is an integer number K of vortical structures in the cavities between two bumps. The highest peak corresponds to K1. Some experiments were undertaken to suppress or at least minimize the sound level. One method which significantly reduced the sound intensity consisted of cutting a narrow strip off the tube along the whole length and replacing it with a smooth strip. This is equivalent to cutting apiece off each bump. A more active method of control consisted of forcing the first bump or cavity by using a set of twelve small speakers positioned in a circle around the tube. This technique only allowed the elimination of the lower sound levels K 1. whereas the Kl mode was only partially reduced.
- Pumps, Filters, Pipes, Tubing, Fittings and Valves
- Fluid Mechanics