STUDY ON NOISE REDUCTION IN SMALL AXIAL FAN : RELATIONSHIPS BETWEEN INLET SHAPE OF CASING, INLET OBSTACLE AND AERODYNAMIC NOISE SOURCE

As the large data center for the latest IoT and AI technology has been increasing, the quantity of small axial flow fan used for server cooling will be drastically increasing. Additionally, the fans are often installed near obstacles such as electronic parts and computer case plates. In server room, since a great many fans are always in operation and the performance is given priority to over the noise reduction, fan noise level for server cooling is much higher than that for cooling other devices. As the result, fan noise becomes the main problem for the worker occupation.In the present study, by measuring the pressure fluctuation on the surface of casing related aerodynamic noise source in detail, relationships between changing inlet shape of casing, inlet obstacle and aerodynamic noise source were evaluated. In addition, by using CFD, factors in which inlet shape made pressure fluctuation decreased and inlet obstacle deteriorated the fluctuation on the casing inlet surface were clarified.