Numerical Study of Steady and Unsteady Turbine Cascade Flows by an Adaptive Unstructured Upwind Approach

• Main Authors: Shun-Jyh Wu, 吳順治
• Other Authors: Chii-Jong Hwang
• Format: Others
• Language: en_US
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/77487208779978018047

博士 === 國立成功大學 === 航空太空工程學系 === 81 === The purpose of this thesis is to study the steady and unsteadyphenomena of subsonic and transonic turbine cascade flows by using a new adaptive upwind finite-volume algorithm on mixed type of meshes. For inviscid and viscous compressible flows, the Euler and full Navier-Stokes equations are solved on the unstructured triangular and/or mixed quadrilateral- triangular meshes. To obtain the unstructured mesh system, several adaptive mesh generation techniques, which includes the concepts of single and dual background meshes, the error indicators for evaluating remeshing parameters, the nodes- clustering methods for generating interior nodes, and the techniques for forming triangles and quadrilaterals, are presented. In the present approach, the multi-step Runge-Kutta time integration, Roe''s flux-difference-splitting Riemann solver, MUSCL differencing with characteristic interpolation variables, and appropriate treatments of boundary conditions are included. For steady-state problems, the non-standard weighting of Runge-Kutta stages, local time steps and residual smoothing are introduced to accelerate the calculations. To validate the current adaptive upwind approaches, the oblique shock reflection at a wall, supersonic flow passing through a channel with a 4% circular arc bump, transonic flows around single and two-element airfoils, laminar boundary layer flow on a flat plate, oblique shock/laminar boundary layer interaction, and turbulent boundary layer flow on a flat plate are investigated. By using the current adaptive approach, steady and unsteady flows of subsonic and transonic turbine cascades are studied. For the inviscid unsteady flows in the rotor passages, the viscous-wake and potential-flow interactions are modeled. These are achieved by prescribing a velocity defect and a small pressure disturbance at the inlet plane of the rotor blade row.