BibTex format
@inproceedings{Basley:2022,
author = {Basley, J and Gouder, K and Morrison, JF},
title = {MIXING AND LARGE-SCALE MODULATION OF A TURBULENT BOUNDARY LAYER PERTURBED BY AN EFFUSION FILM},
year = {2022}
}
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TY - CPAPER
AB - The large-scale modulation of an effusion film injected into a high Reynolds-number boundary layer is investigated for a wide range of film-velocity to freestream-velocity ratios. Particle Image Velocimetry (PIV), visualisations and hot-wire measurements are used to characterise the momentum effects underlying the mixing of the effusion film. For this experiment, the geometry of a turbine blade is idealised in a large-scale facility with a canonical upstream boundary layer where the effusion film and the boundary layer are isothermal. Spectral analysis shows that the injection of the effusion film first promotes near-wall turbulence until the film breaks away from the surface when the velocity ratio reaches a critical value. For higher velocity ratios, large-scale motions from the incoming boundary layer no longer penetrate the sublayer. The associated spectral signature is accompanied by enhanced inter-scale exchanges, as shown by the skewness of the streamwise velocity component and the amplitude modulation coefficients. Use of seeding in the film flow enables the estimation of the concentration of injected fluid in the laser sheet. Joint momentum-concentration data show that the mixing of the film is strongly modulated by the large-scale motions of the turbulent boundary layer, although in different ways depending on the velocity ratio. For very low velocity ratios, large-scale motions are largely unaffected by the film. They encompass the boundary layer down to the injected sublayer and modulate locally the concentration of injected film. For higher velocity ratios, mixing intensifies as the effusion film is injected with momentum and reaches further from the wall. As a result, the concentration of injected fluid in the near-wall region is remotely, yet more intensively modulated by the large-scale motions above the sublayer.
AU - Basley,J
AU - Gouder,K
AU - Morrison,JF
PY - 2022///
TI - MIXING AND LARGE-SCALE MODULATION OF A TURBULENT BOUNDARY LAYER PERTURBED BY AN EFFUSION FILM
ER -