A Numerical Study on Flow Structures around a Rotating Small Axial Fan with High-resolution Computational Scheme

This paper numerically studies flow structures around a rotating small axial fan that is one of general-purpose products. A reference length and velocity are a diameter of the fan and the velocity of impeller at the tip. Based on such reference length and velocity, a Reynolds number is 160,000. The flow around the fan is computed by using large-eddy simulations (LES) with highly accurate and resolution computational scheme. The LES is conducted using the supercomputer in Japan. Results show that flow separates from the edges of the impeller and the tip of the impeller during the rotation. It is observed that multiple vortices are shed from the separated shear layers. Also, it is found that the leading edge and tip vortices show periodic behavior while the trailing edge vortex has unsteady behavior. From above-mentioned observations, it is suggested that an interaction among the vortices observed at the suction side of the impeller could be one of aerodynamic noise sources.