Cavitating flows entail phase change and hence very large and steep density variations in the low pressure regions. These are also very sensitive to: (a) the formation and transport of vapor bubbles, (b) the turbulent fluctuations of pressure and velocity, and (c) the magnitude of noncondensible gases, which are dissolved or ingested in the operating liquid. The presented cavitation model accounts for all these first-order effects, and thus is named as the “full cavitation model.” The phase-change rate expressions are derived from a reduced form of Rayleigh-Plesset equation for bubble dynamics. These rates depend upon local flow conditions (pressure, velocities, turbulence) as well as fluid properties (saturation pressure, densities, and surface tension). The rate expressions employ two empirical constants, which have been calibrated with experimental data covering a very wide range of flow conditions, and do not require adjustments for different problems. The model has been implemented in an advanced, commercial, general-purpose CFD code, CFD-ACE+. Final validation results are presented for flows over hydrofoils, submerged cylindrical bodies, and sharp-edged orifices. Suggestions for possible extensions of the model implementation, e.g., to nonisothermal flows, for ingestion and mixing of noncondensible gases, and for predictions of noise and surface damage are outlined.

Due to complexities in geometry and physics, Computational Fluid Dynamics (CFD) pump simulation has historically been very challenging and time consuming, especially for cases with cavitation. However, with the evolution and innovation of CFD technologies, pump cavitation simulation has improved significantly in recent years. In view of these developments, this paper will discuss a new generation CFD tool for pump cavitation simulation, using an axial flow water pump as a demonstration case. A novel CFD methodology and advanced cavitation model will be presented and discussed. Key components that are relevant to improvement of accuracy and CFD simulation speed will be discussed in detail. An axial flow water pump is chosen as the test case to demonstrate and validate the capability and accuracy of the code discussed. Simulation results include pump head, hydraulic efficiency and cavitation characteristic in terms of incipient Net Positive Suction Head (NPSHi) for the whole pump flow passages using both multiple reference frame (MRF) and transient approaches. Multiple operation conditions, from 70% to 120% of duty flow rate have been evaluated and will be projected against experimental data. Furthermore, simulated cavitation patterns will be compared with video images recorded during the experiments.

Due to complexities in geometry and physics, computational fluid dynamics (CFD) pump simulation has historically been very challenging and time consuming, especially for cases with cavitation. However, with the evolution and innovation of CFD technologies, pump cavitation simulation has improved significantly in recent years. In view of these developments, this paper will discuss a new generation CFD tool for pump cavitation simulation, using an axial flow water pump as a demonstration case. A novel CFD methodology and advanced cavitation model will be presented and discussed. Key components that are relevant to the improvement of accuracy and CFD simulation speed will be discussed in detail. An axial flow water pump is chosen as the test case to demonstrate and validate the capability and accuracy of the code discussed. Simulation results include pump head, hydraulic efficiency, and cavitation characteristic in terms of incipient net positive suction head for the whole pump flow passages using both multiple reference frame and transient approaches. Multiple operation conditions, from 70% to 120% of duty flow rate, have been evaluated and will be projected against experimental data. Furthermore, simulated cavitation patterns will be compared with video images recorded during the experiments.

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