Numerical Exploration of Staged Transverse Injection into Confined Supersonic

Abstract

Staged transverse sonic injection into supersonic flow in a confined environment usually employed in scramjet combustor has been explored numerically using an indigenously developed three-dimensional Reynolds Averaged Navier Stokes solver with Roes scheme and k-w turbulence model. Simulations were carried out for both without injection and with injection in Mach 2 flow behind a backward-facing step in a rectangular duct. Simulation captured all finer details of flow structures including recirculation bubble behind a backward-facing step, barrel shocks and Mach discs caused due to transverse injection and reattachment of shear layer in the downstream wake region. K-w turbulence model with compressibility correction performed extremely well in predicting the overall behaviour of the flow field. The jet from the second injector was found to penetrate more in the free-stream due to the loss of free-stream total pressure across the barrel shock of the first injection point. Excellent agreement of computed profiles of various flow parameters at different axial locations in the duct with experimental results and other numerical results available in the literature demonstrate the robustness and accuracy of the indigenously developed code.

Effects of Inflow Mach Number and Step Height on Supersonic Flows over a Backward-Facing Step

“…The reattachment point is determined where the surface velocity is zero and the reattachment length is defined as the length between the step corner and the reattachment point. Typically, both experimental and numerical studies in the past mainly focus on the low Mach number conditions [17,18,21,25,31]. However, with the hypersonic aircrafts being developed, the investigations of sudden expansion flow in high Mach number conditions such as the airfoil problem have become increasingly important.…”

“…Most of numerical investigations for the backward-facing step in supersonic flow are based on either RANS or LES [10,11,18,[24][25][26]. RANS can give the averaged parameters of the flow field and predict the large-scale fluctuations through modeling, while LES is supposed to be more accurate theoretically, provided that only the subgrid scale eddy should be modeled according to the basic hypothesis of LES that the sub-grid scale is isotropic, and the larger eddies are calculated using Navier-Stokes equations.…”

Dynamics of a supersonic transitional flow over a backward-facing step

“…For the supersonic regime, stability analysis also shows a strong shear-layer induced instability featured with a large frequency range in the separation region [15]. However, there are probably additional mechanisms involved, that are related to compressibility and the occurrence of compression waves at flow reattachment [16,17]. Therefore, it is reasonable to conjecture that a different mechanism may contribute to the transition process in the supersonic case.…”

Low-frequency unsteadiness mechanisms in shock wave/turbulent boundary layer interactions over a backward-facing step

“…The free shear layer then develops towards the downstream wall on which the flow reattaches. Compression waves are generated around the reattachment location, which coalesce into a reattachment shock (Loth, Kailasanath & Lohner 1992; Sriram & Chakraborty 2011). In this configuration the upstream limit of the separation bubble is stationary and only the downstream reattachment shock is present.…”