TURBULENT ENERGY BUDGET IN A TIP LEAKAGE FLOW: A COMPARISON BETWEEN RANS AND LES

摘要

An academic configuration of a single airfoil and a flat casing with clearance, put in the potential core of a jet at Re_c = 9.3 × 10~5, is studied in order to analyse the turbulence modelling. A zonal large-eddy simulation (ZLES), validated against experimental results, is considered as a reference to evaluate two steady Reynolds-averaged Navier-Stokes (RANS) simulations. Both RANS simulations use the original Wilcox k - ω model. They differ on the constitutive relation: one uses the classical Boussinesq constitutive relation, while the other relies on the quadratic constitutive relation (QCR). The analysis focuses on the mean velocities, the Reynolds stresses and a term-to-term decomposition of the turbulent kinetic energy budget on a plane through the clearance. RANS represents quite well the mean velocities, but under-estimates the Reynolds stresses, thus under-estimates every turbulent kinetic energy budget term. The QCR has little effect on the flow and the turbulent quantities. The method allowed a fine analysis of the physics of the turbulence.