DESIGN AND ANALYSIS OF A HIGH PRESSURE TURBINE USING COMPUTATIONAL METHODS FOR SMALL GAS TURBINE APPLICATION

This paper describes the aerodynamic design and analysis of a high-pressure, single-stage axial flow turbine suitable for a small gas turbine engine application using the computational methods. The specifications of the turbine were based on the need of a typical high-pressure compressor and the geometric restrictions of the small gas turbine engine. Base-line design parameters such as flow coefficient, loading coefficient are close to 0.23 and 1.22 respectively with maximum flow expansion in the NGV rows. In the preliminary design mode, the mean-line approach is used to generate the turbine flow path and the design point performance is achieved with three blade sections at hub, mean and tip using the AMDC+KO+MK+BSM loss models to meet the design constraints. An average exit swirl angle of less than 5 degree is achieved leading to minimum losses in the stage. Also, NGV and rotor blade numbers were chosen based on the optimum blade solidity. Blade profile is redesigned using the results from blade-to-blade analysis and through-flow analysis based on the enhanced Dawes BTOB3D flow solver. Using PbCFD (Pushbutton CFD) and commercially available CFD software ANSYS-CFX, aerothermodynamics parameter like pressure ratios, aerodynamic power, and efficiencies are computed and the results are compared with one another. The boundary conditions, convergence criterion, and the turbulence model used in CFD computations are set uniform for comparison with a turbulence intensity of 8 per cent. Grid independence study is performed at design point to optimize the grid size to carryout off-design performance predictions. ANSYS-CFX and PbCFD have predicted higher efficiency of 3.42% and 1.23% respectively with respect to targeted efficiency of 89 per cent