Answer Posted / pradip mungara
From Bernoullie's theorem since the flow velocity increases
at the restriction(e.g. orifice) the pressure drops at that
location. As the reduced pr. equals the vapour pr. of the
liquid ,flowing through, vapor bubbles are formed. A sudden
expansion in the flow area after the restriction causes the
pr. to increase and the vapour bubbles collapse resulting in
erosion of pipe wall and generation of mechanical vibration.
This phenomenom is known CAVITATION.
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