Analysis of Waterhammer in Pipes With Non-Condensable Gases

This paper analyzes waterhammer due to pump transients in pipes containing pockets of non-condensable gases. Solutions ranging between rigid and compressible liquid columns with pressure wave propagation are considered. An energy model is introduced to show if a system is dominated by either rigid or compressible liquid column properties. This “up-front” energy determination results in choosing an efficient formulation for predicting the transient pressure and piping forces for a given system. Example cases are given to demonstrate the solution methods. The effect of different assumptions and parameters are studied. Compressibility of water, gas bubble size, and pump startup are all studied for their effect on the peak pressure reached during a waterhammer event.