TY - JOUR

T1 - Testing Basic Gradient Turbulent Transport Models for Swirl Burners Using PIV and PLIF

AU - Savitskii, Alexey

AU - Lobasov, Aleksei

AU - Sharaborin, Dmitriy

AU - Dulin, Vladimir

N1 - Funding Information: Funding: This research was funded by the Russian Science Foundation, grant number 19‐79‐10225. The equipment was provided within the frame of the state contract with IT SB RAS. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021/11

Y1 - 2021/11

N2 - The present paper reports on the combined stereoscopic particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) measurements of turbulent transport for model swirl burners without combustion. Two flow types were considered, namely the mixing of a free jet with surrounding air for different swirl rates of the jet (Re = 5 × 103) and the mixing of a pilot jet (Re = 2 × 104) with a high‐swirl co‐flow of a generic gas turbine burner (Re = 3 × 104). The measured spatial distributions of the turbulent Reynolds stresses and fluxes were compared with their predictions by gradient turbulent transport models. The local values of the turbulent viscosity and turbulent diffusivity coefficients were evaluated based on Boussinesq’s and gradient diffusion hypotheses. The studied flows with high swirl were characterized by a vortex core breakdown and intensive coherent flow fluctuations associated with large‐scale vortex structures. Therefore, the contribution of the coherent flow fluctuations to the turbulent transport was evaluated based on proper orthogonal decomposition (POD). The turbulent viscosity and diffusion coefficients were also evaluated for the stochastic (residual) component of the velocity fluctuations. The high‐swirl flows with vortex breakdown for the free jet and for the combustion chamber were characterized by intensive turbulent fluctuations, which contributed substantially to the local turbulent transport of mass and momentum. Moreover, the high‐swirl flows were characterized by counter‐gradient transport for one Reynolds shear stress component near the jet axis and in the outer region of the mixing layer.

AB - The present paper reports on the combined stereoscopic particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) measurements of turbulent transport for model swirl burners without combustion. Two flow types were considered, namely the mixing of a free jet with surrounding air for different swirl rates of the jet (Re = 5 × 103) and the mixing of a pilot jet (Re = 2 × 104) with a high‐swirl co‐flow of a generic gas turbine burner (Re = 3 × 104). The measured spatial distributions of the turbulent Reynolds stresses and fluxes were compared with their predictions by gradient turbulent transport models. The local values of the turbulent viscosity and turbulent diffusivity coefficients were evaluated based on Boussinesq’s and gradient diffusion hypotheses. The studied flows with high swirl were characterized by a vortex core breakdown and intensive coherent flow fluctuations associated with large‐scale vortex structures. Therefore, the contribution of the coherent flow fluctuations to the turbulent transport was evaluated based on proper orthogonal decomposition (POD). The turbulent viscosity and diffusion coefficients were also evaluated for the stochastic (residual) component of the velocity fluctuations. The high‐swirl flows with vortex breakdown for the free jet and for the combustion chamber were characterized by intensive turbulent fluctuations, which contributed substantially to the local turbulent transport of mass and momentum. Moreover, the high‐swirl flows were characterized by counter‐gradient transport for one Reynolds shear stress component near the jet axis and in the outer region of the mixing layer.

KW - Boussinesq’s hypothesis

KW - Coherent structures

KW - Gradient diffusion hypothesis

KW - Particle image velocimetry

KW - Planar laser induced fluorescence

KW - Proper orthogonal decomposition

KW - Swirling flows

KW - Turbulent Schmidt number

KW - Vortex breakdown

UR - http://www.scopus.com/inward/record.url?scp=85118176220&partnerID=8YFLogxK

UR - https://www.elibrary.ru/item.asp?id=47518560

U2 - 10.3390/fluids6110383

DO - 10.3390/fluids6110383

M3 - Article

AN - SCOPUS:85118176220

VL - 6

JO - Fluids

JF - Fluids

SN - 2311-5521

IS - 11

M1 - 383

ER -