Investigation on the combustion characteristics of scramjet engine with steady air throttling

Abstract

It is significant to improve the performance of air throttling for combustion control in scramjet engines. Therefore, in order to achieve better combustion enhancement effects with less flowrate, the mechanism of air throttling has been studied in depth. The effects of steady air throttling on the flow field structure of an ethylene scramjet combustor are examined under the condition of isolator entrance Mach number of 3.0, the static temperature of 675 K, and the static pressure of 66 kPa by using numerical simulation. The influences of different jet mass flowrate, jet positions, and jet temperatures on the combustion property of the combustor are also investigated. The results demonstrate that the injection of steady air throttling into the cold flow field of combustor produces more shock wave structures and interacts with the boundary layer, which reduces the actual area of the flow path and leads to lower mainstream velocity and higher pressure. Moreover, the injection of steady air throttling into the combustion flow field of combustor enhances the mixing of ethylene with air, enabling higher combustion efficiency. The results also reveal that as the increasing of injected jet mass flowrate, moving forward of injection position, or the raising in temperature all enhance the combustion performance of combustor. Under the assumption of ensuring the same improvement impact of combustor combustion performance, compared with the 300 K jet, the steady air throttling mass flowrate at a total temperature of 1500 K can be reduced by at least 33.3%.