ISBN 9783843938198

978-3-8439-3819-8, Reihe Luftfahrt

Jan Habermann
Reynolds Stress Anisotropy in a Two-Stage Low-Pressure Turbine

131 Seiten, Dissertation Universität Stuttgart (2018), Softcover, A5

Zusammenfassung / Abstract

Computational fluid dynamics have become an essential part in the design process of aircraft engines to improve performance. The industrially used two-equation linear eddy viscosity turbulence models have weaknesses in predicting the Reynolds stress anisotropy in complex flow situations like in a low-pressure turbine. Higher-order turbulence models, such as differential Reynolds stress transport models (DRSM) are supposed to improve the numerical prediction quality. Until recently, the proposed DRSMs were far more unstable than the LEVMs and thus needed a significantly larger amount of computational time to converge, what made them less attractive for turbine design efforts. Further, DRSMs were not able to account for transition on airfoil surfaces. In 2010, a robust DRSM was presented, that has the potential to be successfully used in turbine design, the SSG/LRR-ω model with simple gradient diffusion. This DRSM was then coupled to the γ-Reθ transition model and, in course of this thesis, calibrated for low-pressure turbine flow conditions. To validate the suitability for low pressure turbine applications of this new model combination and to assess its advantages compared to the LEVMs in predicting the overall flow quantities and the Reynolds stress anisotropy, simulations with industrially used LEVMs (SST, k-ω and k-ω EARSM) and the new DRSM were conducted. For the validation and assessment of new numerical models or model combinations, it is indispensable to compare the numerical results with high sophisticated measured data. Therefore the full Reynolds stress tensor and its anisotropy are experimentally investigated in an engine representative two-stage low pressure axial turbine, the Advanced Turbine Research Demonstrator Rig (ATRD-Rig). Numerical and experimental results are compared to each other and discussed.