中文摘要：

对自主开发的7—40风机进行了性能试验测量和全工况整机数值模拟，并对大中小三种流量下风机蜗壳的内部流场进行了全面的研究。通过对蜗壳内多个横截面的通流速度、静压和二次流分布的详细分析，探讨了三种流量下离心风机蜗壳内部二次旋涡流动的形成和发展、最大和最小主流速度的位置的变动，研究了蜗壳内通流速度方向的扩压等蜗壳空腔内部流动的变化规律，分析了蜗壳对叶轮流动的影响。

英文摘要：

The performance test and numerical simulations on the flow fields of the whole fan of 7-40 type developed by us are conducted. Additionally the variations of the flow fields in the volute casing of the fan at flow rates below, near and above the best efficient point are investigated extensively, focusing on the distributions of the main through flow, static pressure and secondary flow. The variation rules of the flow structures in different sections of the volute casing are discussed, mainly on＂ the formation of the secondary flow eddies, the shift of the positions of the maximum and minimum main through flow as well as the static pressure diffusion along the main flow direction in the casing. The influences of the casing on the exit flow of the impeller are also discussed.