Large Eddy Simulation of a Supersonic Coaxial Helium-Air Jet

The experiment of A. D. Cutler et al. (NASA Langley Research Center) was modeled, in which a round cold helium jet issued into a co-flow air stream. Both flows were nominally at Mach number 1.8 with convective Mach number equal to 0.7. This test provides high accuracy measurements of Pitot pressure, mass fraction, longitudinal velocity and its root mean square. Presented computations were carried out with the use of in-house code zFlare developed in TsAGI. Two sets of multiblock hexahedral grids were constructed, one for RANS computations and the other for LES. Computational domain reproduces the supplying channels, nozzles and the initial region of the jet. LES computational domain spans a full circle in azimuthal direction, while RANS implies axial symmetry. Due to the presence of near-wall domains, the approach adopted for LES was actually hybrid SST-DDES model. SLA modification was enabled to accelerate the development of the mixing layers. Steady RANS computations were conducted with SST and q-omega turbulence models using relaxation method. Time-averaged fields of Pitot pressure, Mach number, longitudinal velocity component and mass fraction were extracted and compared with the experiment.