Gas Release During Transient Cavitation in Pipes

Some applications are presented of a mathematical model concerning water hammer and release of dissolved gas in pipelines in the case where the pressure drops to the vapor pressure of the liquid transported. Column separation and cavitation in extensive parts of the pipeline, referred to as cavitating flow, are dealt with. A smoothing procedure is adopted in order to suppress nonlinear instability. Gas release is found to cause some damping of pressure waves in cases where only cavitating flow occurs. Gas release at a column separation cavity tends to increase the duration of column separation, whereas gas release in a possible cavitating flow region adjacent to the separation diminishes this duration, thus causing considerable damping of pressure peaks following subsequent column separations. Good agreement is obtained with experimental results available in the literature. Further experimentation is required as regards the parameters on which gas release depends.