Investigation of the Flow-Induced Noise and Optimization Design of a Short Tube Throttle Valve

Compared with the globe valves and other on-off valves, cavitation and noise are more severe in the throttle control valve of the refrigerating system due to the higher saturated vapor pressure of the refrigerant. A short tube throttle valve (STTV) is an important throttle control component and cavitation noise easily occurs because of the pressure drop caused by flow throttling. To suppress the cavitation noise, this paper proposed a numerical investigation verified by experimental data into cavitation and noise characteristics inside the STTV. Three kinds of typical throttle valve structures are proposed in this study. The flow field and cavitation noise of the STTV under different refrigerant flow rates were analyzed numerically. The noise levels of the prototype and three optimized structures are comparatively assessed and analyzed. The findings indicate that the level of cavitation noise rises with an increase in flow rate through the STTV. Specifically, when the flow rate transitions from 0.014 kg/s to 0.024 kg/s, there is a corresponding increase in noise levels, moving from 102.8 dB to 122.5 dB. There is less cavitation noise upstream and the flow is stable, while the noise is mainly concentrated downstream with symmetrical distribution characteristics. The distribution seems to have small noise near the internal wall, while large noise is in the center of the downstream in the STTV, and the maximum noise is observed at the corner of the valve seat of the valve outlet. The optimized valve featuring a slope structure on the valve seat significantly reduces cavitation noise, with a maximum noise reduction of 24.94 dB compared to the prototype valve.