关键词: 叶片式预旋喷嘴;落后角;预旋效率;马赫数;雷诺数

Abstract: Cascade vane pre-swirl nozzle has the characteristics of small geometry size and large deviation angle. In order to investigate the performance of the pre-swirl nozzle with small size, the outlet flow field was tested using five hole probe for the cascade vane nozzle. The pressure, velocity and outlet flow angle distributions were measured at Ma=0.2 and 0.3. Deviation angle and pre-swirl effectiveness of the cascade vane nozzle were obtained experimentally, and the numerical simulations were also conducted for the same experimental operating conditions. The significant secondary endwall flow loss, trailing edge loss and obvious boundary layer separation can be observed through the measured total pressure contour and velocity contour. At Ma=0.2 with Reynolds number 5.76×10⁴, the deviation angle of cascade vane nozzle is around 2.84° and the tested pre-swirl effectiveness is only 0.73. At Ma=0.3 with Reynolds number 1.06×10⁵, the pre-swirl effectiveness increases to 0.77. However, the end wall of the experiment makes the tested pre-swirl effectiveness values 6.5% lower. Results also show that the calculations have good agreement with all the measured parameters: the deviations of area averaged total pressure and static pressure were less than 1%, and the deviations of velocity, tangential velocity and outlet flow angle were less than 4%. In addition, the pressure ratio has no influence on the pre-swirl effectiveness, while it would increase first and then remain almost constant with the Reynolds number. At high Reynolds number, the pre-swirl effectiveness of cascade vane nozzle remains 0.85.

Key words: Cascade vane nozzle;Deviation angle;Pre-swirl effectiveness;Mach number;Reynolds number