Evaluation of a liquid–vapor mass transfer model for string cavitation inside the liquid nozzle with non-condensable gas effects

To assess the prediction accuracy of existing cavitation models for in-nozzle string cavitation, elucidate the accumulation characteristics of the vortex flow field on the bubbles, and explore the influence of non-condensable gas in the string cavitation inception and development, a modified cavitation model has been proposed. This modified model is expected to be more precise in predicting string cavitation. In this paper, numerical simulations are carried out in conjunction with visualization experiments, where discrete-phase particles represent the non-condensable gas. Results indicate that the current Zwart–Gerber–Belamri cavitation model fails to account for the effect of the non-condensable gas factor in the modeling process, leading to inaccurate predictions of string cavitation within the nozzle. To address this issue, modification of the mass source term of the cavitation model is proposed based on the Rayleigh–Plesset equation and the bubble surface pressure equation. The modified model demonstrates better accuracy in predicting string cavitation inside the nozzle. The gas nuclei inside the fuel tend to accumulate around the vortex core, influenced by the internal vortex flow field, which further contributes to the string cavitation inception and development. This study proposed and evaluated a more accurate cavitation model and further improved the cavitation initiation and development mechanism.