The current design of low-pressure turbines (LPTs) with steady-blowing vortex generating jets (VGJ) uses steady computational fluid dynamics (CFD). The present work aims to support this design approach by proposing a new semi-empirical transition model for injection-induced laminar-turbulent boundary layer transition. It is based on the detection of cross-flow vortices in the boundary layer which cause inflectional cross-flow velocity profiles. The model is implemented in the CFD code TRACE within the framework of the γ-Reθ transition model and is a reformulated, re-calibrated, and extended version of a previously presented model. It is extensively validated by means of VGJ as well as non-VGJ test cases capturing the local transition process in a physically reasonable way. Quantitative aerodynamic design parameters of several VGJ configurations including steady and periodic-unsteady inflow conditions are predicted in good accordance with experimental values. Furthermore, the quantitative prediction of end-wall flows of LPTs is improved by detecting typical secondary flow structures. For the first time, the newly derived model allows the quantitative design and optimization of LPTs with VGJs.
Modelling Vortex Generating Jet-Induced Transition in Low-Pressure Turbines
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Herbst, F, Fiala, A, & Seume, JR. "Modelling Vortex Generating Jet-Induced Transition in Low-Pressure Turbines." Proceedings of the ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. Volume 6B: Turbomachinery. San Antonio, Texas, USA. June 3–7, 2013. V06BT37A023. ASME. https://doi.org/10.1115/GT2013-94962
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