【摘要】 三元流叶轮轴向长度的选择是高效节能叶轮设计中十分重要的环节。轴向长度在很大程度上决定着叶轮中的流动状态及叶轮性能。轴向长度过长、过短均会引起叶轮内部流动恶化性能变差。 文中比较了不同轴向长度叶轮内的流动特性,叶轮出口边界层动量厚度,参考动量厚度及控制叶轮内流动分离大小的两个参数△W/W_m及W₁/W₂,证明具有最佳轴向长度的叶轮其性能最佳。 文中给出了最佳轴向长度、当量最佳平均单位叶长载荷选择式,给三元流叶轮的设计带来极大方便。实践证明,本文提出的最佳轴向长度的确定方法是行之有效的。更多还原

【Abstract】 The axfal length of three-dimensional impellers in centrifugal compressors is an important geometry parameter for the impeller design with high efficiency and saving energy. To a greater degree, the flow behavior in an impeller and its performance depend on the axial length. If the axial length is too long or short, it will cause that the flow in an impeller is deteriorated and the performance is no good. So it is very important to select axial length in three-dimensional impeller design. In order to explore the axial length influence on the performance of impeller, flow behavior in different axial length impelllers are compared. It shows that in the case of the optimal axial length the diffusion ratio and the maximum Mach number at the entrance of the impellers are minimum and flow behavior is better. Truckenbradt equation is used to calculate the boundary layer momentum thickness and reference momentum thickness. It illustrates that at the optimal axial length the two thicknesses are minimum. Comparing with the parameters△W/ Wm and W1/W2 which control the separation region, at the condition of that △ω/ωm<1is satisfied, w1/w2 is minimum, i. e. separation region is minimum and flow behavior is good. The formulars of choosing the optimal length and equivalent optimal average load in an unit length are deduced. According to the method mentioned above, three samples are provided. They demonstrate that the non-dimension performance curves are flat, the operation regions are wide and the maximum polytropic efficiency of stage is all above 84%. By comparing with the results of experiments the feasibility of the formulars are verified.更多还原