Numerical Simulation of Confined Multiple Transverse Jets
Technical paper, May-Jun 2012
AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR
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Behavior of unconfined transverse jets has been studied extensively, but little work is reported on the flow characteristics of confined transverse jets. The latter has been numerically investigated using a number of RANS codes. The computational results obtained from these codes have been evaluated against the existing experimental data, and the results of a Large-Eddy Simulations LES code reported in the literature. Furthermore, an extensive validation effort has been conducted to characterize the performance of the codes for predicting the flow within a propulsion-related mixing configuration. The validation case involves eight circumferentially spaced transverse jets issuing radially into an axisymmetric main flow, a configuration relevant for gas turbine burners and new liquid rocket engine preburners. The main flow Reynolds number was 1.7 x 10exp 5 and the jet-to-main flow momentum flux ratio was sixteen. The momentum and scalar mixing was investigated through the solution of the Reynolds-Averaged Navier Stokes RANS equations. The solutions of three commercial RANS solvers, Fluent, STAR-CCM, and CFD, are compared to experimental data and large-eddy simulation LES results available in literature. Due to demonstrated periodicity, only a one-eighth pie-shaped section of the geometry was considered. The different commercial codes used the same geometry, grid, boundary conditions, and variations of the k-epsilon turbulence model. The LES results obtained from literature used a different grid, but the same geometry. All numerical simulations using the above mentioned codes capture salient flow structures such as the counter-rotating vortex pair CRVP. Experimental data used for validation of the codes include mean axial velocity and jet fluid mixture fraction profiles at three distinct axial locations, jet trajectory, turbulent kinetic energy distributions, and velocity and mixture fraction cross-plane distributions.
- Fluid Mechanics