Pressure fluctuation and cavitation noise characteristics of hydrofoil at different temperatures.

The current work investigates the cavitating flow over a NACA0015 hydrofoil at temperatures of 285.65K and 305.95K using experiment and simulation. The results show that higher-temperature liquid flow can significantly decrease the periodic fluctuation frequency of the attached cavity, reduce the scale of shedding cavitation clouds, and suppress the collapse of discrete small bubbles downstream. It also inhibits the instability of the attached cavity, effectively mitigating the energy impact and the cavitation noise caused by collapse, especially the high-frequency region of cavitation noise. The simulation results indicated that higher-temperature liquid flow can reduce the range and the intensity of vortex structures in the flow field. At different temperatures, the strict periodic pulsation characteristics of cavitation noise are consistent with the attached cavity in the spectral-temporal domain. Although the cavitation states corresponding to the high sound intensity regions are different, they both have wideband characteristics. Especially over multiple cycles, the cavitation states corresponding to these high sound-intensity regions are consistent. The research results provide valuable references for predicting cavitation development state solely through noise signals. This paper discusses the significant influence of larger temperature difference on the cavitating flow and cavitation noise of the NACA0015 hydrofoil, leading to the following main conclusions: • From both experimental and simulation perspectives, it can be demonstrated that higher-temperature liquid flow effectively suppresses the intense periodic fluctuation frequency of the attached cavity. The scale of shedding cavitation clouds on the hydrofoil surface and the distribution of vorticity are significantly reduced. • Under higher-temperature liquid flow conditions, the tail of the attached cavity is more stable, and the detachment of cavities occurs at a faster condensation rate, effectively suppressing the impact of high-frequency small bubble collapse on the hydrofoil surface and the high-frequency cavitation noise generated by the collapse. • The spectral-temporal domain analysis of the hydrofoil cavitation noise shows consistent periodicity with the cavitation structure at different temperatures. Although the high-intensity regions of noise correspond to different cavitation flow structures, they all exhibit wideband characteristics. Notably, higher-temperature liquid flow significantly reduces cavitation noise across the entire frequency spectrum, providing a valuable reference for accurately predicting the cavitation development state. [ABSTRACT FROM AUTHOR]