向心透平叶片角动量分布的优化

OPTIMIZATION OF ANGULAR MOMENTUM DISTRIBUTION FOR RADIAL INWARD FLOW TURBINES

以 n条子午流线 ,给出满足约束条件的各自角动量分布的若干不同组合构成初始复合形 ,做复合形每一顶点处该向心透平叶轮 S2 流面与跨叶片面势流场分析 ,并以二元紊流边界层动量厚度计算经三元修正 ,分析叶轮效率 ,最终使复合形法成功应用于向心透平叶片角动量分布的优化。该方法也适用于离心叶轮中叶片加载量的优化。

A complex method is used in optimization of angular momentum distribution for radial inward flow turbines. Firstly, select a number of points ｛X j｝=｛(λ 1 λ 2 … λ n) T j｝ which satisfy all restriction conditions and are taken as the apexes of an initial complex. Then, at every kind of angular momentum distribution ( λ 1 λ 2 … λ n) T j do computation of the main flow field for the S 2 flow surface and for the S 1 flow surface of the turbine impeller, do computation of momentum thickness of the blade’s two dimensional turbulent boundary layer, and do correction of the three dimensional effect on the thickness. By that, estimate the impeller efficiency η . Finally, it can make object function f (X)=1-η have a minimum value. This method can also suit centrifugal impellers. In this paper, an application example is given for a radial inward flow turbine. This optimization of angular momentum distribution can make the turbine have isentropic efficiency 86% and have better off design characteristics.