Abstract The experimental investigation examined the influence of high turbulence intensity, large scales, and turbulence anisotropy on turbulence decay within the intermediate turbine duct (ITD). The paper focuses on two different test configurations of the intermediate turbine duct, which is an annular s-shaped channel used in turbofan engines to guide the flow from the high-pressure turbine (HPT) at a smaller radius to the low-pressure turbine (LPT) at a higher radius. Two state-of the-art intermediate turbine duct concepts are in focus. The most common duct is the turbine center frame (TCF), featuring nonturning struts. The exit-to-inlet area ratio of the TCF is higher than one, leading to a flow deceleration through the duct.—On the other hand, the turbine vane frame (TVF), also known as integrated concept, can be considered as a direct evolution of the diffusive duct. The integrated concept involves integrating the function of the LP turbine's first vane row into the duct by introducing turning struts and splitters. The overall Mach number increases from the inlet to the exit within the component. The present study obtained hot-wire anemometry measurements using a triaxial and a single hot-film probe. The acquired measurement data illustrates different turbulent mixing within the intermediate turbine duct. Moreover, the high turbulence quantities at the exit of the TCF duct dominated the shroud region. In contrast, the flow field at the TVF exit is dominated by TVF secondary flow and vane wakes.
Hafizovic et al. (Fri,) studied this question.