The Flow Analysis For Gate Operating Mechanism Of Middle And Small Sized Francis Turbine

The flow analysis for flow passage components of turbine is the key step of turbine optimization. Based on the flow rules are real reflected, we can propose the optimized scheme in order to improve performance of turbine. The paper analyzed flow for gate operating mechanism of 10MW vertical turbine. On the basis of the known parameter, the 3D modeling is built by UG and CAD. Finally, the paper analyzed flow of conditions(maximum opening,optimum operating condition and small opening).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 RNG 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 and wall. The wall function method is adopted by near wall treatment. The finite volume method(second-order upwind ) applicated in equation dispersed and the SIMPLEC 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 there are three points:1,The flow velocity and pressure distribution of gate operating mechanism are uniform changing(velocity decreasing and pressure increasing), and has a good symmetry along the circle.2,The meiobar range was liable to be occurred in the trailing edge of guide vane, as a results, the cavitation damage happened. 3,The guide vane opening could affect efficiency, the pressure difference between positive and back of guide vane is minimum in optimum operating condition, and also the hydraulic loss. And in any other conditions, the pressure difference and hydraulic loss will increase. So the newly developed guide vane should be seek for the optimum operating by model test.