Journal of South China University of Technology(Natural Science Edition) ›› 2012, Vol. 40 ›› Issue (2): 39-44.

• Mechanics • Previous Articles     Next Articles

Space-Time Unsteady Flow of Moving Grids in Pelton Bucket Based on Differential Geometry

Shen Na1  Han Feng-qin2  Kubota Takashi2   

  1.  1.School of Electrical Engineering,Guangzhou College of South China University of Technology,Guangzhou 510800,Guangdong,China; 2. School of Electric Power,South China University of Technology,Guangzhou 510640,Guangdong,China
  • Received:2011-03-14 Online:2012-02-25 Published:2012-01-04
  • Contact: 沈娜(1984-) ，女，博士，主要从事流体机械数值仿真及优化设计研究． E-mail:ShenNa@ foxmail.com
  • About author:沈娜(1984-) ，女，博士，主要从事流体机械数值仿真及优化设计研究．
  • Supported by:

    浙江省重大科技专项资助项目( 2008C11057) ; 广东省教改委项目( BKYB2011099)

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Abstract:

In order to apply the concept of unsteady flow in space and time domains to the design of Pelton buckets,a numerical visualization of the complicated unsteady water film flow on the free surface of a rotating bucket is indispensable. In this paper,the inner surface of a bucket is described by using the boundary-fitted grids with nonorthogonal curvilinear local coordinates. Then,the natural basic vectors and their partial differentials are precisely
acquired based on the differential geometry,and the local curvature along the inner surface,the geodesic and the small surface area of the bucket are obtained. Moreover,the moving grids of the water film are successfully projected onto the bucket’s inner surface,and a projection algorithm is proposed to numerically visualize the moving grids of the unsteady water film flowing from the bucket cutout and the water separation edge. The visualization results are finally compared with the photos taken in the model test,which verifies the effectiveness of the proposed method.

Key words: Pelton turbine, rotating bucket, unsteady flow, water film flow, natural basic vector, differential geometry