Effects of Geometric Parameters and Inflow Conditions on Flow in Aggressive Inter-Turbine Ducts

Abstract

Demands for high efficient and environmental friendly aircrafts drive civil engines towards higher bypass ratios and smaller axial length. Both of these lead to great increase in the mean rise angle of inter-turbine ducts (ITDs), which determines the high curvature and high diffusion rate of its internal flow fields. In order to reduce the flow loss of aggressive ITDs, it is necessary to study the complex flow mechanism in ITDs, explore the factors influencing the flow and performance in ITDs, and provide technical supports to develop advanced turbine design technologies for highbypass turbofan engines. In this paper, numerical simulations of a typical aggressive ITD with struts between high and low pressure turbines of a large civil engine are carried out, and a method for comprehensively evaluating the aerodynamic performance of ITDs considering compressibility, area ratio, outlet flow angle is proposed. With this method, the influence of geometric parameters on ITDs flow structure and performance is discussed. The study shows that the area ratio has important influence on the flow field inside the ITDs, and the optimization of area distribution can improve the aerodynamic performance of ITDs. Finally, the influence of inlet aerodynamic conditions such as inlet Mach number and turbulence intensity on flow structure and performance of ITDs is analysed.