Abstract: To study the effects of impellers in a cover-plate pre-swirl system，based on a 3D simplified model，steady numerical simulations were carried out to study the characteristics of the flow，power consumption and temperature reduction in the pre-swirl system with and without impellers，with the inlet total pressure and total temperature，outlet pressure，and the mass flow delivered to the blade being constant. The results show that，as the air accelerated by the impellers，the difference of velocity between the air and the rotating supply holes would be reduced，and the centrifugal boost pressure rise in the cover-plate cavity would be enhanced. And with a smaller velocity difference，the pressure loss at the entrance and in the passage of supply hole will also be reduced. As a result，the static pressure at the outlet of pre-swirl nozzle would be reduced，which would lead to a higher pressure ratio and a higher swirl ratio at the nozzle outlet. Eventually the higher swirl ratio would cause the system power consumption to decrease by 56.88kW and the temperature reduction to increase by 10.2K.

Key words: Pre-swirl system；Rotating flow；Impellers；Power consumption；Temperature reduction

摘要： 为了研究叶轮在盖板式预旋系统中的作用，基于简化三维模型，在保证系统进口总压总温、出口压力以及供气流量不变的条件下，分别对有/无叶轮的预旋系统流动特性、功耗特性和温降特性进行了稳态数值模拟。结果表明:叶轮通过对盖板腔内的气体做功，提高了气流的旋转比，增大了盖板腔的离心升压效果，并因为降低了供气孔入口气流的相对速度从而减小了供气孔内的压力损失。进而使得喷嘴出口的静压降低，喷嘴进出口压比和喷嘴出口气流旋转比随之增大。最终更高的喷嘴出口气流旋转比会导致预旋系统的整体功耗减小约56.88kW，系统温降提高约10.2K。

关键词: 预旋系统；旋流；叶轮；功耗；温降