Fluid Transient Phenomena Accompanied with Column Separation in Fluid Power Pipeline : 1st Report, On the Horizontal Pipeline Downstream of a Valve Instantaneously Closed

Abstract

A mathematical model capable of predicting a pressure rise associated with cavity collapse and cavitation duration following a column separation with accuracy enough for practical usage, on the downstream side of a valve instantaneously closed in a fluid power pipeline, was investigated. Particular attention has been paid to assessing the effect of gas released from liquid during the growing phase of the cavity. For that purpose, mechanism of commencement, growth and collapse of gas bubbles and volume of gas released were observed by using a valve made of transparent acrylic resin and a high speed camera. So far as the timing and pressure peak upon collapse of the first cavity are concerned, the predicted results from the present "gas-nonbubbly flow" model, in which the effects of gas released at the separated cavity and of an unsteady shear resistance in pipe flow were considered, agreed with the measured results within 5 per cent at worst.