Experimental aero-acoustic characterization of axial fan fitted with shaped tip end-plates

In the present work a new fan blade was fitted with tip end-plates, designed to control the swirl level of leakage vortex. The new geometry is characterized by a tip pressure side vortex that has been identified as an important contributor for controlling the leakage flow. The vortex results in a vena contracta effect and consequentially the mass leaking is un-fed close to the blade leading edge and in so doing leakage flow is reduced with an associated improvement in both aerodynamic and acoustic performance. The aerodynamic and acoustic effects of the MVB modified blade have been established by fitting them to a fan rotor and experimental testing in a fully ducted configuration and then in a semi-anechoic chamber. Three fans acoustic emissions were compared through a focus on coherent flow structures and tip-leakage flow.