Design and analysis of HP-turbine for variable cycle engine

A supersonic highly loaded high-pressure turbine with large enthalpy drop was designed for a variable cycle engine (VCE) in two operating modes of high and low bypass ratio by using similarity principle, and the blade profiles were implemented by means of a new three-dimensional (3-D) profile design method based on S₁ stream surface. Then, 3-D numerical simulations were performed for the turbine in both operating modes under different thermodynamic cycle parameters to confirm the design methods and results. One-equation turbulence model of Spalart-Allmaras was applied to solve Reynolds averaged Navier-Stokes equations, whilst the transition model of Abu-Ghanam Shaw was introduced into the calculations to capture the development process of boundary layer on blade surface. The results of simulations indicate that excellent aerodynamic performances are available in both operating modes with overall efficiency of 92.79% and 92.31%, respectively, which are superior to anticipated targets; the used profile design method by S₁ stream surface is more precise and effective than conventional cylinder method for turbine blade, since 3-D characteristics of flow fields are considered elaborately.