汽轮机低压排汽缸与末两级耦合流动的三维数值模拟  

Combined 3D Numerical Analysis of the Low Pressure Exhaust Hood Coupling With the Last Two Cascades in Steam Turbine

作　　者：樊涛[1] 谢永慧[1] 张荻[1] 孙弼[1] 

机构地区：[1]西安交通大学能源与动力工程学院,陕西省西安市710049

出　　处：《中国电机工程学报》2007年第26期90-95,共6页Proceedings of the CSEE

基　　金：国家863高技术基金项目(2006AA04Z404)~~

摘　　要：数值模拟一直是研究大功率汽轮机低压排汽缸内流场的主要方法之一。但是,国内外的研究大多只构造单个排汽缸模型进行分析,并未考虑到末级动叶排出汽流的不均匀性等因素的影响。为了更加透彻地认识排汽缸内三维流动的细节,文中通过求解由RNGk-ε双方程湍流模型封闭的三维时均N-S方程对汽轮机低压排汽缸和末两级耦合流动进行了数值分析,并采用"混合平面"方法处理末两级叶栅及其与排汽缸之间动静面的参数传递和相互干扰的问题,获得了排汽缸内部的压力和速度分布。与单独排汽缸数值分析相比,该方法能够获得更为接近实际的数值结果,并为汽轮机通流部分及排汽缸的设计研究提供了新思路,所得到的结果可为排汽缸的优化设计提供参考。Numerical methods are widely used to study the flow field in large power steam turbines. However, most of the previous numerical simulations studied the exhaust hood separately without taking account of the effect of the inhomogeneous flow from the last stage. In order to obtain more accurate and detailed information of the three dimensional flow in exhaust hood, a combined numerical model, which couples the exhaust hood with the last two stages, was introduced in this paper, meanwhile, the mixing plane approach was used. The Reynolds averaged N-S equations with RNG k-e turbulence model was adopted to analyze the flow field in the exhaust hood considering the coupling effect between the exhaust hood and the last two stages. It is shown clearly that the presented combined model can give more accurate numerical results than the previous single model. The study provides a more reasonable numerical model for investigating the flow filed in the exhaust hood and it may give some significant data for the optimal design of exhaust hood in steam turbine.

关 键 词：排汽缸 数值分析 耦合计算 混合平面 

分 类 号：TK262[动力工程及工程热物理—动力机械及工程]