Investigation Of Aerodynamic Design Method For Last Stage Blade Of Turbine And Non-axisymmetric Endwall Profiling Technology

Aerodynamic design method for the last stage of steam turbine is investigated systematically. Two important components of turbine long blade aerodynamic design system- S2 design calculation and S1 flow solution is concentrated on. Because of large secondary flow loss located in hub region of last stage rotor of steam turbine, which results from large flow turning angle, the mechanism of non-axisymmetric endwall profiling for reduction of secondary flow loss in turbine cascade is explored by numerical simulation.Streamline curvature method is applied to solve S2 design calculation problem of the last stage of a steam turbine. Some discussion about aerodynamic design of last stage of steam turbine has been given basing on the result of S2 design calculation mentioned above. Comparison and appraise has been presented for uniform circulation control and controlled-vortex aerodynamics. Analysis shows that controlled-vortex aerodynamics can make reaction more uniform ,but it is limited to some extent because of larger leaving loss when it is applied to last stage of steam turbine.Finite volume time marching method is applied to solve blade-to-blade flow on any revolution surface. Multi-grid technology is used to speed up the converge process. In addition, this paper has introduced a kind of new method to obtain H-grid of two-dimension cascade which involves solution of Possion equation. The grid from this method can simulate leading and trailing edge of blade much more accurately than that from algebraic method when grid number is equal, at the same time the grid from solution of Possion equation is better in orthogonality and smoothness than that from algebraic method. Calculation result of blade-to-blade flow shows: much more clear shock originated from trailing edge of blade can be captured when grid from solution of Possion equation is used than equal number grid from algebraic method.As an advanced method for reduction of secondary flow loss within turbine cascade, non-axisymmetric endwall profiling has a promising future in gas turbine and power engineer. In this paper, numerical simulation has been carried out to obtained detailed flow structure in conventional turbine cascade and two kinds of turbine cascade...