| The value of hydro-turbine distributor'end clearance, flow field distribution in end clearance have great influence on the cavitation and leakage of guide vanes, thus have influence on the cavitation and operation stability of turbine. This paper mainly studies the effect of changes in height of end clearance on cavitation of guide vanes.The paper analyzed flow for gate operating mechanism includes end clearance of HL180/D06A turbine. On the basis of the known parameter, the 3D modeling is built by UG and CAD. Finally, the paper analyzed flow in different end clearance of maximum flow and optimum flow conditions.In the process of flow analysis, the paper use uncoupled implicit, choose the stationary continuity and Reynolds N-S as governing equations, finally, the equations closured by Realizable k ?ε. The grids of computational domain are Cooper, the mesh generation achieved in gambit. The selection of boundary conditions are velocity_inlet, pressure_outlet, periodic, interface and wall. The wall function method is adopted by near wall treatment. The second-order upwind applicated in equation dispersed and the SIMPLE applicated by coupling between pressure and velocity. Finally, the paper gets the velocity and pressure distribution and explored the flow characteristics in all the conditions. So the results provide evidence for improving performance.The results showed that: The cavitation happened in range of outlet on blade'front, inlet on blade'back and journal. With the increase of vane end clearance, the range of cavitation in end clearance generated greater, the stronger in reflowed after the journal. In conditions of installation, the end clearance as small as possible. This research can be a reference for choice of height of end clearance , design and installation of distributor. |
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