Abstract: To address the issue of indoor unit operating noise affecting user comfort, structural optimization was employed to reduce surging noise at the air outlet. Based on an extreme dimensional analysis of the fan and base housing assembly, it was discovered that the gap between the rear fan surface and the left end of the base housing was too large, which could easily lead to surging noise at the air outlet. The following structural optimization schemes were proposed: firstly, applying adhesive to the left air duct end surface of the base housing, and secondly, adding ribs to the right end surface of the base housing. Experimental results show that this scheme allows the rear fan surface to exceed the interior left end surface of the base housing air duct, creating a more uniform airflow channel on the left side and effectively reducing surging noise at the air outlet.

Key words: Air conditioning, Indoor unit, Noise, Fan, Bottom shell