Modular design framework of an axisymmetric wrap-around thrust-optimized combined nozzle

Abstract

Listen

Translate article

This work develops a computational analysis framework of an axisymmetric two-stream nozzle for wrap-around combined cycle engines from the aspects of contour design methodology, design feasibility, and performance augmentation technology. This research proposes a modular design method that combines the inverse design for upstream turbojet/ramjet nozzles and the maximum thrust design for the collective mixing region based on the method of characteristics. An improved algorithm for the inviscid slip line is proposed on requirement to model the inevitable mixing layer between the two streams in mixing region. The validation and verification benchmarks confirm the robustness, accuracy, and effectiveness of the method from theoretical and practical perspective. The influences of the exit flow patterns and geometric conditions on the inverse design reveal its practicability boundaries, and it refines a direct judgment criterion with the verified credibility for the rational flow matching in the combined nozzle. The thrust and economic characteristics in relation to the flow patterns of upstream nozzle exits are further investigated. Results indicate that greater levels of linear exit flow angle distributions benefits both thrust coefficient and thrust–area ratio, with performance increments exceeding 6.35% and 43.76%, respectively, when the flowfield is transformed from the “shock-free” to “shock-induced” state.