Numerical and experimental evaluation of cavitation flow around axisymmetric cavitators

摘要

The primary objective of this research is to study the cavitating effects of fluid flow past different axisymmetric cavitator in the upper sub-critical flow regime, which corresponds to the Reynolds number (2 × 10~4 to 2 × 10~5). Experiments are conducted in a water tunnel with a fluid flow velocity of 30 to 60 m/s at a constant rate of injection. The commercial software tool, ANSYS Fluent 18.1, is used to simplify three dimensional Reynolds averaged Navier Stokes equation with the compressible fluid flow by considering the pressure-based solver with standard K- ω turbulence model. The transport equation-based Schnerr and Sauer cavitation model is employed to study the cavitation phenomena. The finite volume discretisation method is implemented to evaluate the cavity length and diameter, respectively. A comparison of the numerical and experimental results shows that the numerical method can predict accurately the shape parameters of the natural cavitation phenomena such as cavity length, cavity diameter, and cavity shape. Results reported that with an increase in velocity, the cavity length and diameter increased to 250 and 20%, respectively. With a decrease in the cavitator angle at constant Reynolds number, the drag coefficient decreases up to 40%. Also, for the 30° cavitator, the drag coefficient rises by 28% when cavitation number is increased from 0.25 to 0.32.