直板型叶片扩压器流场的实验测量与数值研究

利用激光多普勒测速仪（LDV）测量系统测量了3个不同的工况下离心风机直板型叶片扩压器内部的三维速度场，并对叶片扩压器内部流场及其随流量变化的规律进行了分析．同时，在实验测量的基础上对整个实验风机进行了非定常数值模拟，并对比分析了扩压器内部及其上游流场的数值计算和实验结果．结果表明：数值结果与实验结果吻合得很好；沿着扩压器的流道方向气流的速度逐渐减小，非定常速度脉动也逐渐减弱，非定常速度脉动的频率和叶轮的叶片通过频率一致；随着流量的减小，扩压器的扩压能力逐渐增强，扩压器叶片压力面附近的低速区逐渐减小，扩压器上游及内部流场受蜗壳的盘、盖侧空腔影响逐渐增大．

Experimental and Numerical Study on Flows in Straight Plate Diffuser of Centrifugal Fan

The experimental and numerical studies were conducted for the flows in a straight plate diffuser of a centrifugal fan under three different operating conditions. The detailed 3D flow field in the straight plate diffuser was measured via laser Doppler velocimetry under different flow rates. Numerical simulations for the transient process were performed and compared with the cor- responding experimental results. The time averaged numerical velocities in the straight plate dif- fuser and its upstream passage agree quite well with the experimental data. The results show that the air velocity declines gradually and the unsteady effect decays fast in the vaned diffuser with the distance from the impeller. With the decrease of flow flux, the low velocity region near the pressure side of the vaned diffuser reduces, and the secondary flow effect from the cavities near shroud and hub enhances. The diffuser loses its diffusion capability under large flux.