Computation And Analysis Of Complicated Flow Field By Large-eddy Simulation

Though numerous gas turbines have been used worldwide for over half a century, the flow on the turbomachinery blades is not yet completely understood. Precise calculation is needed to achieve high efficiency engines. With increasing computing power, Large Eddy Simulation could be a useful simulation tool for gas turbine axial compressor design.The large eddy simulation, which adopted Dynamic Subgrid-Scalel, six order precision WENO-SYM scheme for the convection flux and the compact scheme for the Viscous flux, is used in the thesis. The implicit Newton iteraction scheme was used for temporal discretization. Deep investigations were conducted.Firstly, the supersonic turbulence boundary layer on a flat plate was simulated, which the inlet boundary condition adopted synthetic eddy method. The supersonic boundary layer coherent structures were similar to compressible turbulence. Strips of uniform positive and negative fluctuations existed and the cane(or single-leg hairpin) cortices were dominant.Secondly, on the foundation of the validity of the SEM inlet boundary condition, the shock wave turbulence boundary layer interaction was simulated. The low-frequency shock motions were related to the low-frequency pulsation of the separation bubbleFinally, the sharp leading edge, acting as a tripping device, disturbed the freestream; the suction surface profiles appear to separate both at the leading edge and again somewhat beyond midchord. With an incidence angle of 5 degrees, the pressure surface exhibits a large region of laminar flow, transition on the pressure surface appears to be incomplete.