具有阻尼拉金的汽轮机末级三维流动特性研究  

Influence of lashing wire on three dimensional viscous flow of last stage in steam turbine

作　　者：李平[1] 张荻[1] 何林[1] 谢永慧[1] 

机构地区：[1]西安交通大学能源与动力工程学院,陕西西安710049

出　　处：《热科学与技术》2011年第2期159-165,共7页Journal of Thermal Science and Technology

基　　金：国家高技术研究发展计划(863计划)资助项目(2009AA04Z102)

摘　　要：阻尼拉金可以有效提高汽轮机叶片的振动安全性,但是另一方面将影响叶栅通道流动,从而降低其效率。为了获得具有阻尼拉金叶片叶栅通道的详细流动状况,采用RNGkε-湍流模型、壁面函数法、结构化网格、混合平面法建立了某汽轮机末级三维黏性流动的数值模型,并且对比分析了具有阻尼拉金和不具有阻尼拉金时该末级的三维黏性流动状况。结果表明:阻尼拉金附近各特征截面处动叶表面静压和通道内流线相比无阻尼拉金时均发生了显著变化,拉金的存在对吸力面流场的影响更为显著,吸力面阻尼拉金周围形成了各种涡旋运动。同时具有阻尼拉金汽轮机等熵效率降低了0.39%,表明阻尼拉金对于汽轮机末级流动性能具有较大影响。Vibration safety of the turbine blade could be improved effectively by using lashing wires,however,the lashing wire would affect the flow of cascade passage,which resulted in the reduction of the efficiency.In order to gain the detail information of the flow in the cascade passage of the blade with lashing wire,the numerical model and calculation method have been developed by adopting the RNG k-ε turbulence model,wall-function method,structure grid and mixing plane approach for detailed three-dimensional viscous flow analysis of the last stage in a 150MW condensing steam turbine.Furthermore,the three-dimensional viscous flows of the last stage with lashing wire and without lashing wire were analyzed Numerical results indicate that the static pressure of blade and the streamline near the lashing wire change significantly,especially on the suction surface.It is shown that there are vortices system on the suction surface as flow separation appears.For the isentropic efficiency loss of last stage,the model with lashing wire compared with the model without lashing wire show reduction of 0.39%,so the lashing wire has great influence on the flow field of last stage in steam turbine.

关 键 词：汽轮机 末级 阻尼拉金 叶顶间隙 数值模拟 

分 类 号：TK262[动力工程及工程热物理—动力机械及工程]