多分流喷咀叶栅气动变分有限元分析

在蒸汽透平的高压级中,喷咀叶栅的高宽比相当小,一般l/B<1,端损比较严重。为了减少这种损失,本文提出一种新的由主、分流叶片组成的多分流喷咀叶栅结构,以改善高压级喷咀叶栅的气动性能。为了对这种多分流喷咀叶栅进行全流场计算,本文采用了较先进的气动变分有限元方法。以国产30万千瓦机组高压第一压力级为例,对实际运行的带矩形加强筋的窜喷咀结构,带锥形加强筋的窄喷咀结构以及由主、分流叶片组成的多分流喷咀叶栅结构进行了全流场的气动有限元计算。从计算所得的速度分布曲线可知,带矩形加强筋的窄喷咀结构的气动性能最差,而由主、分流叶片组成的多分流喷咀叶栅的气动性能最好,它是改善蒸汽透平高压级热经济性的有效途径。

Aerodynamic Analysis of the Nozzle Cascade with Many Splitter Vanes by the Finite Element Method

In the high pressure stages of a steam turbine, the ratio of the height to the width of the nozzle cascade is very small (generally, l/B<1); as a result there is heavy flow losses at the ends. To reduce the great losses, this paper presents a new nozzle cascade with many splitter vanes consisting of main blades and splitter vanes to improve the aerodynamic performance of the nozzle cascade of the high pressure stages.To solve the problem of the flow in the nozzle cascade with many splitter vanes, this paper adopts the more advanced finite element method. Taking the first high pressure stage of the home-made 300,000 Kilowatt generating set for example, the authors work out an aerodynamic calculation, by means of the finite element method, for the narrow nozzle cascade with rectangular ribs used in practice and with wedged ribs and with the nozzle cascade consisting of many splitter vanes made up of main blades and splitter vanes.From the curvilineals of the velocity distribution obtained by the calculation, the aerodynamic performance of the narrow nozzle cascade with rectangular ribs is the worst, and the aerodynamic performance of the nozzle cascade with many splitter vanes consisting of main blades and splitter vanes is the best. Therefore it is an effective method to improve thermo-economy of the high pressure stages in the steam turbine.