Flame stabilization enhancement by microjet-based virtual shock wave generators in a supersonic combustor

Abstract

Two flow control methods, namely, the microjet array (MJA) and the conventional shock wave generator (SWG), were employed to enhance the chemical reaction in a strut-based supersonic combustor. The Mach number, stagnation temperature, and stagnation pressure of the inflow were 2.92 K, 1650 K, and 2.60 MPa, respectively. The combustor was fueled by hydrogen and liquid kerosene. The case without any flow control method (the baseline case) was also reported for comparison. It was found that the recirculation flow at the strut base was essential to flame stabilization. A self-sustaining hydrogen flame was achieved in the baseline case. However, a flame blow-off was observed when kerosene was injected into the combustor. This was attributed to the short residence time in the recirculation flow and the long ignition delay time of kerosene. To extend the operation envelope of the combustor, additional shock waves were introduced into the combustor using MJAs and SWGs. The shock waves successfully enlarged the recirculation flow at the strut base and significantly enhanced the chemical reaction. Self-sustaining hydrogen/kerosene flames were achieved in the cases with MJAs and SWGs. Although the chemical reaction in the case with MJAs was slightly less vigorous than that in the case with SWGs, these two cases shared the same combustion mode. The MJAs had the potential to replace the conventional SWGs in terms of flame stabilization enhancement.