Unsteady Simulations of Flow Field and Scalar Mixing in Transverse Jets

Abstract

This paper presents numerical simulations of flow and scalar mixing in two different jet in crossflow configurations. The testcases are chosen to resemble the dilution mixing processes in gas turbine combustion chambers. Unsteady simulations employing two different computational approaches are presented: unsteady Reynolds-Averaged Navier-Stokes (URANS) and Scale-Adaptive Simulations (SAS). The results obtained by each method are compared, analyzed, and validated against experimental data. The importance of the reproduction of the large-scale unsteady coherent vortical structures in the numerical simulation is demonstrated. Both URANS and SAS revealed the typical jet in crossflow vortical structures. The SAS method was able to resolve smaller structures than URANS on the same computational grid. The quantitative prediction accuracy of time-averaged velocities and temperatures is satisfactory for both methods. In contrast, the steady-state Reynolds-Averaged Navier-Stokes (RANS) computations failed for the present testcases.