Simultaneous measurements of flow-induced noise and two-phase flow regime in expansion valves.

Flow-induced noise generated by the expansion devices is disturbing to the user because of its highfrequency properties. In the paper, a pumped R134a loop and the simultaneous measurements including the accelerometer, the microphone, the high-speed pressure transducer, and the high-speed camera are utilized. Thus, the flow-induced noise can be related to specific flow movements recorded by the camera. The observed frequency range of the gurgling noise is between 7.5 kHz to 10 kHz, whereas that for the hissing noise is above 10 kHz. The gurgling noise is generated by the flow oscillating movement whereas the hissing noise is caused by the flow-structure interaction. The hissing noise can be enhanced by the structural modes and exists in all kinds of flow regimes. The gurgling noise only exists when TXV inlet has two-phase flow. The acceleration signal matches the microphone signal and the accelerometer can be used to simulate the flow-induced noise.