膨張弁から発生する自励音に関する研究

抄録

In air conditioning system, pure tone self-excited sound is generated around an expansion valve in rare case. However, the mechanism of the noise is unclear. In our previous report, self-excited sound generation experiments were performed when air was flown through the expansion valve by using an air compressor as the first stage of elucidation of the self-excited sound phenomenon. In this report, three-dimensional CFD analysis using air are performed and the numerical results are compared with the experimental results. The CDF analysis simulates self-excited sound of around 1400 Hz that is generated in the experiment. From the numerical results, a pseudo-shock wave is generated and vibrates in downstream of an expansion valve when the self-excited sound is generated. The pressure mode is also generated in the tube. We conjecture the self-excited sound occurs due to the couple problem between oscillation of pseudo-shock wave and variation of pressure in the tube.