Enhancing Cryogenic Cavitation Prediction Through Incorporating Modified Cavitation and Turbulence Models

Abstract

Cavitating flow prediction is essential for designing cavitation-resistant hydraulic machines. Despite the advances achieved in normal-temperature cavitation prediction, cryogenic cavitation prediction has remained a challenging task in which thermal effects play a significant role. The present study aims to enhance the prediction of cryogenic cavitation, and both the cavitation and turbulence models are improved simultaneously. The original cavitation model embedded in the CFX flow solver is modified by incorporating additional source terms (such as mass and heat transfer rates) for dual evaporation and condensation processes. The RNG k-e turbulence model is modified on the basis of the filter-based turbulence model and density correction method to permit a smooth prediction of turbulence eddy viscosity, which mitigates the overestimation of the turbulence length scale in the cryogenic cavity (which is intrinsic to the original RNG k-e turbulence model). The modified cavitation and turbulence models are implemented through CFX Expression Language (CEL) within the CFX frame. To verify the modified models and the enhancement of cryogenic cavitation prediction, Hord's liquified nitrogen (LN2) and liquefied hydrogen (LH2) experiments over a hydrofoil and ogive are used, and cavitating flow simulation is conducted for each of the test cases. When using the modified models, the predicted temperature and pressure curves agree well with the measured values, and the predicted cavity lengths are much closer to the measured lengths. It is proven that the cryogenic cavitating flow can be well depicted by the modified models.

Preliminary design and performance analysis of the liquid turbine for supercritical compressed air energy storage systems

“…The maximum total efficiency of the radial inflow liquid turbine was 74.8%. Li et al [22], Song et al [23,24], He et al [25] and Sun et al [26] studied numerically the cavitation behaviour of the liquid turbine. Ren et al [27] studied the strength of the impeller, while Wang et al [28] predicted the axial thrust loading on the impeller.…”

Performance and flow characteristics of the liquid turbine for supercritical compressed air energy storage system

“…The positive displacement expander was preliminarily applied in refrigeration systems, but its performance was limited by the friction and internal leakage inside the expander. The liquid turbine was widely used in various systems and mainly included the impulse type [12][13][14]21,22] and the reaction type [5,[23][24][25][26][27]. Elliot [12] studied experimentally the performance of the single-stage and two-stages two-phase turbines with various two-phase fluids, including nitrogen-water, R22 and steam-water.…”

“…Wang et al [39] studied the influence of the impeller faring cone on cavitation. Sun et al [23] added thermal and turbulence effects into the Rayleigh-Plasset model. Li et al [40,41] presented preliminary design method of liquid turbines for SC-CAES and applied cavitation models to design the annular nozzle used in multistage two-phase turbines.…”