Initiation of Waterhammer in Horizontal and Nearly Horizontal Pipes Containing Steam and Subcooled Water

Localized slug formation from a stratified flow of steam and subcooled water in a pipe traps a steam bubble, which collapses rapidly and causes a waterhammer. This phenomenon was studied experimentally at low pressures. Several tests, including measurement of the critical conditions for waterhammer initiation, were performed. An analytical model was developed that can predict whether waterhammer initiation will occur for given flow conditions. Predictions of this model agree well with experimental results. The use of the model in evaluating the susceptibility of a piping system to condensation waterhammer is described.