A unique and innovative approach to significantly increasing the thrust performance of ejector-configured, rocket-based combined-cycle (RBCC) engines is proposed. The approach involves oscillating (switching) the rocket exhaust at high frequency (the dynamic ejector), rather than permitting it to simply flow coaxially with the induced air as in a conventional ejector configuration. Since the sole mechanism for transferring momentum and energy between the two streams in a conventional ejector is viscous shear through turbulent jet mixing, very large losses result. This leads to lower thrust levels (hence, specific impulse) than those achievable using a more efficient method of momentum and energy exchange. It is shown herein that oscillation of the rocket exhaust using secondary fluid injection (as in thrust vector control techniques) results in a far more efficient transfer of momentum and energy, leading to very significant increases in specific impulse, probably in excess of 50% thrust augmentation. The proposed concept is responsive to the solicitation's subtopic calling for "high thrust performance of ejector-ramjets...at take-off of the hypersonic vehicle..." Indeed, the performance benefits derived from the proposed concept occur principally at take-off.
