Ignition delay time in swirling supersonic flow

Supersonic hydrogen–air cylindrical mixing layer is numerically analyzed to investigate the effect of inlet swirl on ignition delay time in scramjets. Combustion is treated using detailed chemical kinetics. One-equation turbulence model of Spalart and Allmaras is chosen to study the problem and advection upstream splitting method is used as computational scheme. The results show that swirling both fuel and oxidizer streams may drastically decrease the ignition distance in supersonic combustion, unlike using the swirl just in fuel stream which has no helpful effect.

► Ignition of hydrogen–air supersonic cylindrical mixing layer is numerically analyzed.
► Attention is paid to the ignition distance estimation and reduction by inflow swirl.
► Using the swirl just in fuel stream has no useful effect on ignition distance.
► If the swirl is used in both streams, the ignition distance decreases significantly by increasing swirl angle.