Three-dimensional simulation of turbulent cavitating flows in a hollow-jet valve

Cavitation appears in a wide variety of fluid machinery, and can often cause negative impacts on performance and structural integrity. A main computational difficulty for cavitation is the large density ratio between liquid and vapor phases, around 1000 for water under normal temperature and pressure conditions. Moreover, cavitating flows are usually turbulent and the interfacial dynamics is complex. The fast time scales associated with turbulent cavitation also poses substantial challenges computationally and experimentally. In the present study, pressure-based algorithms are adopted to simulate three-dimensional turbulent cavitating flows in a hollow-jet valve. The Favre-averaged Navier-Stokes equations are employed along with a transport equation-based cavitation model and the k - Ε two-equation turbulence model. Both steady state and time dependant computations are conducted. The time dependency of the flow field reflects the auto-oscillations of the cavity, formed at the needle tip of the hollow-jet valve. The pressure field throughout the flow domain, as well as the density field inside the cavity oscillates quasi-periodically in response to cavity oscillations. For the case investigated, the difference in the detailed cavitation dynamics between time dependent and steady state cases does not exhibit substantial influence on the overall flow pattern.