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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

# Measurement and Simulation of Turbulent Mixing in a Jet in Crossflow

[+] Author and Article Information
Flavio Cesar Cunha Galeazzo

Division of Combustion Technology, Engler-Bunte-Institute, Karlsruhe Institute of Technology, Engler-Bunte-Ring 1, 76131 Karlsruhe, Germanyflavio.galeazzo@kit.edu

Georg Donnert1

Division of Combustion Technology, Engler-Bunte-Institute, Karlsruhe Institute of Technology, Engler-Bunte-Ring 1, 76131 Karlsruhe, Germany

Peter Habisreuther, Nikolaos Zarzalis

Division of Combustion Technology, Engler-Bunte-Institute, Karlsruhe Institute of Technology, Engler-Bunte-Ring 1, 76131 Karlsruhe, Germany

Richard J. Valdes

Siemens Energy, Inc., EN 323, 4400 Alafaya Trail, MC Q3-042, Orlando, FL 32826

Werner Krebs

Siemens AG, PG PE3, Mellinghofer Str. 55, 45466 Muelheim an der Ruhr, Germany

1

J. Eng. Gas Turbines Power 133(6), 061504 (Feb 16, 2011) (10 pages) doi:10.1115/1.4002319 History: Received June 10, 2010; Revised July 02, 2010; Published February 16, 2011; Online February 16, 2011

## Abstract

Computational fluid dynamics (CFD) has an important role in current research. While large eddy simulations (LES) are now common practice in academia, Reynolds-averaged Navier–Stokes (RANS) simulations are still very common in the industry. Using RANS allows faster simulations, however, the choice of the turbulence model has a bigger impact on the results. An important influence of the turbulence modeling is the description of turbulent mixing. Experience has shown that often inaccurate simulations of combustion processes originate from an inadequate description of the mixing field. A simple turbulent flow and mixing configuration of major theoretical and practical importance is the jet in crossflow (JIC). Due to its good fuel-air mixing capability over a small distance, JIC is favored by gas turbine manufacturers. As the design of the mixing process is the key to creating stable low $NOx$ combustion systems, reliable predictive tools and detailed understanding of this basic system are still demanded. Therefore, the current study has re-investigated the JIC configuration under engine relevant conditions both experimentally and numerically using the most sophisticated tools available today. The combination of planar particle image velocimetry and laser induced fluorescence was used to measure the turbulent velocity and concentration fields as well as to determine the correlations of the Reynolds stress tensor $ui′uj′¯$ and the Reynolds flux vector $ui′c′¯$. Boundary conditions were determined using laser Doppler velocimetry. The comparisons between the measurements and simulation using RANS and LES showed that the mean velocity field was well described using the SST turbulence model. However, the Reynolds stresses and more so, the Reynolds fluxes deviate substantially from the measured data. The systematic variation of the turbulent Schmidt number reveals the limited influence of this parameter indicating that the basic modeling is amiss. The results of the LES simulation using the standard Smagorinsky model were found to provide much better agreement with the experiments also in the description of turbulent mixing.

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## Figures

Figure 1

Scheme of the jet in crossflow phenomenology

Figure 2

Overview of the channel with dimensions

Figure 3

Overview of the 2D-PIV/LIF measurement technique

Figure 4

Computational grid on the symmetry plane, fine grid. Detail of the jet inlet at the lower right side.

Figure 5

Profiles of the velocity components U/Ucross and W/Ucross and specific Reynolds stresses u′u′¯/Ucross2 and w′w′¯/Ucross2 using different grids. Dashed line, coarse grid; solid line, fine grid; dashed-dotted, finest grid.

Figure 6

Profiles of velocity components U/Ucross and W/Ucross and specific Reynolds stresses u′u′¯/Ucross2 and w′w′¯/Ucross2 1D above the jet inlet, z/D=1 and y/D=0. Dashed line, k-ε model; solid line, SST model; dashed-dotted line, LES; points, measurement.

Figure 7

Developing velocity U/Ucross along the x direction, z/D=6.75, and y/D=0. Dashed line, k-ε model; solid line, SST model; points, measurement.

Figure 8

Line plots of velocity component U/Ucross at the symmetry plane, y/D=0. Dashed line, k-ε model; solid line, SST model; dashed-dotted line, LES; points, measurement.

Figure 9

Two-dimensional maps of velocity components U/Ucross and V/Ucross and specific Reynolds stress components u′u′¯/Ucross2, v′v′¯/Ucross2, and u′v′¯/Ucross2, z/D=1.5. Measurements, left column; simulation using the k-ε turbulence model, middle column; and using the SST turbulence model, right column.

Figure 10

Line plots of velocity component U/Ucross and specific Reynolds stress component u′u′¯/Ucross2 at the symmetry plane, y/D=0. Dashed line, k-ε model; solid line, SST model; dashed-dotted line, LES; points, measurement.

Figure 11

Two-dimensional maps of specific Reynolds stress component u′u′¯/Ucross, z/D=1.5. Measurements, left column; simulation using LES, right column.

Figure 12

Two-dimensional maps of dimensionless concentration C and specific Reynolds flux component u′c′¯/Ucross, z/D=1.5. Measurements, left column; simulation using the k-ε turbulence model, middle column; and using the SST turbulence model, right column.

Figure 13

Two dimensional maps of dimensionless concentration C and specific Reynolds flux component u′c′¯/Ucross, z/D=1.5. Measurements, left column; simulation using LES, right column.

Figure 14

Line plots of dimensionless concentration C, dimensionless concentration standard variation c′¯ and specific Reynolds flux component u′c′¯/Ucross at the symmetry plane; y/D=0. Dashed line, k-ε model; solid line, SST model; dashed-dotted line, LES; points, measurement.

Figure 15

Two-dimensional maps of dimensionless concentration C, z/D=1.5, for simulations using the SST turbulence model and turbulent Schmidt numbers of 0.3, 0.5, and 0.7.

## Errata

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