文档介绍：Journal of Sound and <ibration (1999) 225(3), 515}526
Article No. , available online at
NOISE CAUSED BY CAVITATING BUTTERFLY
AND MONOVAR VALVES
H. HASSIS
& & %
Ecole Nationale d1Ingenieurs de ¹unis, . 37, ¸e Belvedere 1002, ¹unis, ¹unisia
(Received 7 September 1998, and in ,nal form 11 March 1999)
An experimental study of the e!ects of cavitation was carried out through an
analysis of cavitating Butter#y and Monovar values. Focus is particularly placed
on both unsteady pressure and acoustic pressure #uctuations. In this paper,
the e!ects of cavitation on local #uctuation pressure (turbulence), acoustic
propagation (damping and sound velocity), resonance frequencies and level of
noise are presented.
( 1999 Academic Press
1. INTRODUCTION
Industrial piping systems can experience severe low-frequency vibration caused by
internal #ow of the conveyed #uid. Valves, diaphragms (singularities) 2 can result
in annoying and even unbearable noise and high vibration [1}8]. Prediction
methods are needed to design costly piping systems against such risks.
In the case of single-phase -ow, Gibert [1, 9] showed with experimental
investigations that the source of vibration is often related to the unsteady turbulent
#ow which occurs at any singularities. Pressure #uctuations arising from such #ow
singularities can be separated into two quite distinct zones: (1) in the downstream
region nearby to the singularity location (de"ned by a length 4}10 times the pipe's
diameter, D), the #uctuations of pressure and velocity are dominated by an
unsteady turbulent "eld; it cannot excite any low-frequencies vibration of pipes; (2)
away from the singularity, the #uctuations of pressure and velocity are dominated
by an acoustic pressure #uctuation caused by a system of standing waves which
oscillate randomly in time; at su$ciently low frequencies, only plane waves should
be considered.
In the case of cavitating -ow, the medium is highl