Unsteady Flow Field and Noise Characteristics of a Small Axial Flow Fan Used in Narrow Space

Unsteady flow field and noise characteristics of a small axial flow fan used in narrow spaces are experimentally studied. To simulate the flow field in narrow spaces, a flat plate is placed at a certain distance downstream of the fan outlet. By varying the spacing between the plate and the fan, the blockage effect on the fan exit flow and the associated noise level is investigated. The flow field at the location of 3mm downstream of the fan casing in the axial direction is measured using a three-dimensional laser Doppler velocimetry. As for fan noise, the tested fan is installed in an anechoic room, and the noise is measured with a microphone located 100mm upstream of the fan inlet. The experimental results show that the flow field downstream of the axial flow fan and the fan noise change significantly in accordance with the spacing between the fan exit and the blockage plate.