The Effect of Load Control on the Performance of Contra-Rotating Fans

Abstract

In recent years, few studies focused on adjusting the load distribution of contra-rotating fan (CRF) blades. To improve the overall performance of CRFs, we used a design code to build 32 sets of CRFs to determine the effects of three factors—the front and rear rotor load matching, the load distribution of each rotor and the axial distance between the rotors—on the total pressure rise and efficiency of CRFs using numerical calculations. The relationship between the CRF blades load and velocity components was theoretically analyzed using blade element analysis and the forward problem method. According to the performance curve, it can be concluded that the rear rotor (RR) is the key factor that determines the performance of CRFs. Through analyzing Mach number contours from different perspectives, the relationship between velocity and adjustment load was verified. Furthermore, the flow field characteristics for three specific CRFs were explored at the stall points, design points and choke points to reveal their flow mechanisms. This study provides a reference for the CRF blade design method.

Suppression of Stall-Induced Instability and Positive Slope at Low Flow Rates of an Axial Fan With Two-Dimensional Anti-Stall Fin

“…This flow pattern could cause performance degradation in the stalling flow rates and be closely related to noise, vibration, and system instability. In particular, the backflow became more assertive at lower flow rates [13][14][15][16][17]. Here, in the case of centrifugal fluid machinery, the rotating stall may be observed only between the blade passages rather than the inlet passage; this study relates to an axial fan.…”