Investigating the aerodynamic design of a novel tandem fan with a partial-span booster rotor

Abstract

This paper investigates the modified design of a conventional transonic fan based on a new tandem fan concept with a partial-span rotor, which can significantly enhance the pressurization capacity and flow capacity of the fan's core. The design principles of essential geometric parameters are determined, and the advantages of the new concept are confirmed. The results reveal that the tandem rotor performs better when the pressure surface of the booster rotor is closer to the suction surface of the fan rotor (PP=15%) and its trailing edge is farther from the leading edge of the fan rotor (AO=12%). The introduction of the booster rotor enhances the load near the stator's hub, which can be controlled by modifying the hub profile. Owing to the deficit of the throat area, the blade number of stators must be reduced, but this will lead to an insufficient operation range. After comprehensive consideration, the end-bending angle is fixed at 6°, which can extend the stall margin by 5.5%. In comparison to the baseline fan, the new concept improves the flow capacity by 6.1% and the core's total pressure ratio by approximately 20%. Furthermore, an improvement in the efficiency of more than 5% is obtained at the same specific mass flow compared with the trend line. The time-averaged results of the performance are almost the same as the steady results, and the fluctuation is mainly induced by the interaction between the tip vortex and the stator surfaces.