Research On Numerical Simulation On Unstructured Grid In Turbomechinery

Because of the irregular geometry of turbomachinery isn’t easy to handle and there are somecomplex configurations such as tip clearance and film cooling hole, it is difficult to generatestructured grid with high quality in numerical simulation. Due to unstructured grid have greatflexibility to irregularly geometry, it was widely applied in engineering field.In this work, the method of numerical simulation on unstructured grid has been studied, and animplicit code for solve three-dimensional viscous compressible flow on unstructured grid hasdeveloped using Fortran. The governing equations were discretized in space using a finite-volumetechnique. The inviscid flux is calculated using the Roe approximate Riemann solver, withleast-square method extrapolation. Newton’s mehod and Roe approximate Jacobians scheme wereused to achieve implicit time advance. One equation Spalart-Allmaras model was used to simulatingturbulent flow. Three representative flow cases include plate, transonic turbine vane Mark-Ⅱ andCW-22were simulated. The results of numerical simulation show favorable agreement with exactsolution in theory and experimental date, the flow phenomenon such as shock and secondary flow ispredicted accurately, these suggest that this unstructured implicit Naver-Stokes flow solver predictaerodynamic performance correctly.Another work in this dissertation is study effect of the location of penny platform in variable statorvane on endwall flow. Most of modern jet engines used variable stator vanes(VSV), in order to enablethe required rotational movement of the vanes, the gap between the overhanging ends of the vane tipsand the endwalls need to be quite large and the effect of this gap cannot be ignored in compressordesign. Through experiment and numerical simulation of simplified VSV model, this paper studiedthe effect of different penny platform locations on the flow in endwalls region. The results show thatthere are two factors affect the loss of endwalls flow: the leakage lead by aerodynamic loading and themixing of flow around the penny platform; Optimization of the location and size of the pennyplatform in order to cover the front end of the aerofoil could decrease the leakage and flow loss andimprove aerodynamic performance.