The Effect of Gaseous Cavitation on Fluid Transients

Gaseous cavitation, alternately termed gas release, is investigated for turbulent pipe flows subjected to transient wave motion. Experimental data are presented that exhibit developing two-component flow (air or carbon dioxide and water mixtures) in a 295 m laboratory pipeline; the flow is characterized by wave dispersion due to the increase in void fraction. An analytical model based on the method of characteristics yields simultaneous solutions for pressure, velocity and void fraction. The greatest uncertainty in the formulation is the rate of gas release; here it is allowed to depend upon the difference between saturation and instantaneous line pressures.