A new type of low drag Scramjet combustor based on turbulent mixing enhancement

In the present study, a new type of low drag Scramjet engine is proposed by means of smooth wall design inside the combustor. The key technology to achieve this goal is the well mixing of fuel and air in the combustor. The new mixing technology is developed based on the stability theory of supersonic mixing layer. The stability of a planar supersonic free shear layer at Mc=0.5 has been analyzed. It has been found that the three-dimensional instability waves will accelerate the instability and transition in the mixing layer. The fuel injector using mixing enhancement method based on three - dimensional unstable structure has been applied in the new Scramjet combustor, with which no flame holders, cavities, compression and expansion ramps are needed. Demonstration experiment of the combustor at flight condition of Mach number around 6 has been conducted on the direct connecting facility. The experiments have shown that the ignition may be achieved automatically wi thout any artificial ignition and flam holder devices, and sustained stable combustion may take place. The significant thrust increments of the combustor models have been obtained, which are evaluated by means of wall pressure integration. Copyright © 2008 by Qing SHen and Faming Guan.