Research on the mechanism of high-frequency whistling noise of air conditioners based on LES

Abstract This study investigates the generation mechanism of high-frequency whistling noise in the pipeline system of air-conditioner compressors using Large Eddy Simulation (LES) combined with numerical computation and experimental analysis. The research finds that the L-shaped insert structure induces vortex shedding due to the abrupt reduction in cross-sectional area, generating flow-induced noise. Moreover, when the vortex shedding frequency is close to the natural frequency of the pipeline, it excites deep-cavity vortex-sound coupling resonance, further amplifying the noise. Simulations and experiments demonstrate that increasing the insertion depth (e.g., from 6 mm to 9 mm) significantly increases the noise intensity, while using a T-shaped tee structure can effectively eliminate the noise. The study proposes optimization recommendations: limiting the insertion depth to 0.3 times the exhaust pipe diameter and replacing the right-angle welded structure with a streamlined T-shaped tee to suppress noise. The results provide a theoretical basis for high-frequency noise control in engineering applications.