Experimental and Numerical Analysis of Two-Phase Flows in Plunge Pools

The current capacity of many spillways may be insufficient due to the increase in flood flows as a result of climate change. In those cases, the dam may be overtopped, generating new loading scenarios downstream of the dam. To date, information regarding the behavior of air-water flows in the plunge pool of free-falling jets is scarce. This study combines experimental and numerical approaches to analyze the submerged hydraulic jump generated downstream of overflow nappe impinging jets. A back-flushing Pitot tube and an optical probe were used to measure the velocity field and air entrainment rate. The velocity field allows to validate computational fluid dynamics (CFD) simulations. The choice of the turbulence model played a key role in the wall jet resolution. To the best of our knowledge, for the first time, it was possible to estimate the Sauter mean air bubble diameter in the entire submerged hydraulic jump. The results are in agreement with recordings obtained with a high-speed camera.