Implementation of a roughness element to trip transition in large-eddy simulation

The increase of the thrust/weight ratio of aircraft engines is extremely restricted by different 3-D flow loss mechanisms. One of them is the corner separation that can form at the junction between a blade suction side and a hub or shroud. In this paper, in order to further investigate the turbulent characteristics of corner separation, large-eddy simulation (LES) is conducted on a compressor cascade configuration using NACA65 blade profiles (chord based Reynolds number: 3.82 × 10 5), in comparison with the previous obtained experimental data. Using the shear-improved Smagorinsky model as subgrid-scale model, the LES gives a good description of the mean aerodynamics of the corner separation, especially for the blade surface static pressure coefficient and the total pressure losses. The turbulent dynamics is then analyzed in detail, in consideration of the turbulent structures, the one-point velocity spectra, and the turbulence anisotropy. Within the recirculation region, the energy appears to concentrate around the largest turbulent eddies, with fairly isotropic characteristics. Concerning the dynamics, an aperiodic shedding of hairpin vortices seems to induce an unsteadiness of the separation envelope.

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“…More details about the numerical schemes, and evaluations on a flat-plate boundary layer case, can be found in Ref. 39.…”

Section: A Numerical Schemesmentioning

confidence: 99%

Large-eddy simulation of 3-D corner separation in a linear compressor cascade

Gao

Zambonini

et al. 2015

Physics of Fluids

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“…The inviscid flux interpolation uses a four-point centered scheme. In the LES zone, a fourth-order artificial / 1 viscosity is used (definition in Boudet et al [15]), with a coefficient evolving smoothly from 0.003 at the lower end-wall, up to 0.02 above. Increased numerical viscosity is used in peripheral regions.…”

Section: B Zonal Large-eddy Simulationmentioning

confidence: 99%

Wavelet Analysis of a Blade Tip-Leakage Flow

et al. 2018

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“…The IVM is tested with a flat-plate boundary layer at Re δ2 = 1968, inspired by Jiménez et al [40]. The reference geometry defined in [39] is used in this study: the streamwise extent L x = 0.3m, the wall-normal height L y = 2δ(x = L x ) = 11.7mm and the spanwise width…”

Section: Convergence Check With Longer Channel: 3πhmentioning

confidence: 99%

“…A global constant time step of 4 × 10 −8 s is used for the flat-plate LES simulations, which gives a Courant number of 1.8. The laminar-turbulent transition is forced by a source term that acts as a tripping band, following Boudet et al [39].…”

Section: Convergence Check With Longer Channel: 3πhmentioning

confidence: 99%