Development of a test rig for the investigation of flow-induced mechanisms of sound generation at radial fans

A low sound pressure level is a crucial quality feature for industrial and non-industrial radial fans. The scientific literature documents numerous mechanisms of flow-induced sound generation that can occur in a radial fan. Nevertheless, not all sound generation mechanisms are considered well-understood today and thus are still dealt with in ongoing research. This work develops an experimental setup to investigate the different mechanisms of flow-induced sound generation in radial fans. The aim is to close the existing gap between available experimental research on axial and radial fans. One critical factor for the experimental investigation of flow-induced sound generation in fans is the control of inflow. Due to the design of radial fans, the fluid flow deflects from the axial supply duct to the radial direction upstream of the impeller, generating a complex flow field with limited control possibilities. Hence, we designed a test rig that improves the control of inflow conditions, aiming to resolve the superposed sound generation mechanisms in acoustic measurements. This paper presents the key features of the test rig and some first experimental results. The investigation of the distinct sound generation mechanisms is left to future work based on the introduced test rig.