Numerical Investigation on Effect of Nozzle on the Performance of Continuous Rotating Detonation Turbojet Combined Engine

Abstract

Numerical simulation of flow fields of a continuous rotating detonation turbojet combined engine(CRDTCE)with coaxial double combustion chamber model was carried out to study the influence of the configuration of nozzles on the flow field structure and performance of the CRDTCE. 40% oxygen-rich air was adopted as oxidant and kerosene steam was adopted as fuel. The physical model was composed of an annular rotary detonation combustion chamber with an outer-ring inner-diameter of 93 mm, an outer diameter of 113 mm and a length of 85 mm, and the turbojet center passage with a diameter of 83 mm and a length of 85 mm. The computational domain was the combustor and nozzle flow field of a CRDTCE with shared straight nozzle, independent straight nozzle and Laval nozzles with different convergence-ratios. The results show that the detonation wave propagates steadily in the combustion chamber under different nozzle conditions. Different nozzle configurations have obvious influence on flow field structure and parameters in detonation combustion chamber. Compared with the condition with straight nozzle, the presence of Laval nozzles can enhance the pressure and propagation speed of detonation wave in combustion chamber. The increase of convergence ratio can lead to premixed air injection being non-uniform not uniform, affecting the stability of self-sustaining propagation of detonation wave. On the other hand, the pressure and propagation speed of the detonation wave decrease slightly under the condition of shared straight nozzle, and the wave head height increases. Under the conditions described in this paper, the Laval nozzle with larger convergence ratio has a significant improvement effect on the parameters at the nozzle outlet, and the thrust and specific impulse of the engine is most significantly improved for up to 16%.