Modeling Vortex Generating Jet Induced Transition in Low Pressure Turbines

Abstract

The current design of lowpressure turbines (LPTs) with steadyblowing vortex generating jets (VGJs) uses steady computational fluid dynamics (CFD). The present work aims to support this design approach by proposing a new semiempirical transition model for injectioninduced laminarturbulent boundary layer transition. It is based on the detection of crossflow vortices in the boundary layer which cause inflectional crossflow velocity profiles. The model is implemented in the CFD code TRACE within the framework of the خ³Reخ¸ transition model and is a reformulated, recalibrated, and extended version of a previously presented model. It is extensively validated by means of VGJ as well as nonVGJ test cases capturing the local transition process in a physically reasonable way. Quantitative aerodynamic design parameters of several VGJ configurations including steady and periodicunsteady inflow conditions are predicted in good accordance with experimental values. Furthermore, the quantitative prediction of endwall 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.