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Corresponding Author

Hosien, M.

Subject Area

Mechanical Power Engineering

Article Type

Original Study

Abstract

In the present study the sound pressure measurements were obtained for five configurations, con. –div. wedge, circular cylinder, rear facing step, forward facing step and 60° symmetric wedge. For each configuration two sizes, 10 mm and 20 mm, were used. Spectrograms were recorded with a 1/3 octave band. A wide range of velocities and cavitation numbers were tested to observe its effect upon the noise. The results indicated that for all tested configurations, at constant flow velocity there was no clear relationship between the sound pressure level and cavitation number. The general trend was the sound pressure level increased as the cavitation number decreased reaching abroad peak and then decreased again. The sound pressure level was found to be strongly dependent on the flow velocity for the five configurations. For each configuration at fixed values of cavitation number there was a clear power relation between SPL and the flow velocity. The velocity exponent varied widely with both the cavitation number and cavitation source configurations, although not with cavitation source size. For instance, it is found that, for velocities ranging from 20-40 m / sec and constant cavitation source for 20 mm 60 symmetric wedge, the velocity exponent ranged from 2.3 to 6.2 depending on the cavitation number. The magnitude of the sound pressure level might be independent of the size of the cavitation source for all configurations tested except the con.-div. wedge. The velocity exponent for the broad band width was found to confirm the present theoretical results which indicate that the sound pressure level various at U4 at constant cavitation number.

Keywords

Cavitation; Noise; sounds pressure level

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