Research On Aerothermodynamics Of Blade Cascades In Turbines

With fast development of computer technology and maturation of CFD method, CFD plays an increasingly important role in the design and analysis of advanced turbomachinery. The researches in this dissertation are accordingly carried out around development of a CFD solver and numerical investigation of a multistage radial inflow turbine.With OpenFoam CFD solver software package, this paper develops a set of program based on the solution of Euler/Favre-averaged Navier-Stokes equations. It can predict inviscid and viscous, compressible, steady flow. This program employs TVD scheme with different limiter (MinMod, SMART, etc.) for the evaluation of numerical advective flux, ICCG and Biconjugate Gradients-CG algorithm for solving discretized system. For the prediction of turbulent flow fields, different turbulence models, such as high Reynold's number k- e model and renormalization group k- ε model, etc., are available for choice. A unified algorithm is derivated to predict flows at full speed. The reliability, accuracy, and flexibility of the developed solver is validated through a number of numerical test cases ranging from simple to complex.In addition, this article studys a multistage radial inflow turbine. Aerodynamic performance of a three-stage radial inflow turbine is investigated with numerical simulation. Detailed flow fields and flow patterns, such as secondary flows, etc., in the radial turbine impeller are presented and discussed in this paper. Fisrt, the global computational results are compared with the designed data. Second, the details of flow at the first stage of three stages radial turbine and at all are analysed. An aft load stator blade, a front load impeller and the optimized return channel are applicable in the multi stage radial inflow turbine design. Last, the working performances, that is, the variations of power and efficiency of the three stages radial turbine with the converted mass flow rate, are calculated under different rotational speeds.In order to independence establish CFD software, this paper derives Navier-Stokes equations on non-inertial system and Favre-averaged equations, and Reynolds stress tensor on the basis of fluid mechanical fundamental.