Effect of blended blade tip and winglet on aerodynamic and aeroacoustic performances of a diagonal fan

Tip clearance flow significantly influences the aerodynamic and aeroacoustic performances of a fan. Its mechanism and control have remained a hotspot in the field of turbomachinery. In this paper, blended blade tip and winglet (BBTW) technology is proposed based on the combination of blended blade and end wall and winglet technologies, while the flow field and sound field of an original blade and the BBTW-blade of a diagonal fan are numerically simulated. The calculation results show that the BBTW design reduces the pressure difference between the suction surface and the pressure surface in the blade tip area and enhances the necking effect of tip clearance, thus inhibiting tip clearance leakage flow and improving the aerodynamic performance of the diagonal fan. In addition, as BBTW weakens the tip leakage vortex intensity, thereby reducing the sound pressure level of the near-field and the far-field noise.