喷管对连续旋转爆轰涡喷组合发动机性能影响的数值研究

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

采用共轴环包式双燃烧室模型,通过数值模拟探讨了尾喷管结构参数对连续旋转爆轰涡喷组合发动机燃烧室及喷管流场结构和性能的影响。采用40%富氧空气为氧化剂,煤油蒸气为燃料,物理模型由外环内径93 mm、外径113 mm、长度85 mm的环形旋转爆轰燃烧室和内腔直径83 mm、长度85 mm的共轴涡喷中心流道组成,计算域包括带有共用等直喷管、独立等直喷管以及2种不同收缩比的拉法尔喷管的连续旋转爆轰涡喷组合发动机的燃烧室和喷管流场。数值结果表明:旋转爆轰燃烧室在发动机带有不同尾喷管时均能够形成稳定自持传播的爆轰波,不同喷管构型对爆轰燃烧室内的流场结构与参数影响较明显。相比于独立等直喷管,对于爆轰波峰值静压与波速的影响上拉法尔喷管起到有效的提升作用,但收缩比的增加会导致预混气喷注不均匀,影响爆轰波自持传播的稳定性;共用等直喷管则轻微地降低了爆轰波峰值静压与传播速度,提高了预混气喷注区域和波头的高度。在该文所选工况下,较大收缩比的拉法尔喷管能明显地改善喷管出口的状态,对发动机的推力与燃料比冲提升最显著,高达16%。

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%.