中心锥喷管喉道比参数对旋转爆轰燃烧影响的数值研究

Numerical Study on Effects of Throat Ratio Parameter of Aerospike Nozzle on Rotating Detonation Combustion

关键词:  旋转爆轰发动机  中心锥喷管  反射激波  喉道比  燃烧模态  推进性能

Key words:  Rotating detonation engine  Aerospike nozzle  Reflected shock wave  Throat ratio  Combustion mode  Propulsion performance

摘要:

旋转爆轰发动机的推进性能与尾喷管的设计有关。为探究中心锥喷管的喉道比参数如何影响旋转爆轰波的传播模态及旋转爆轰发动机的推进性能，采用三维欧拉方程结合氢气/空气基元反应模型，对不同喉道比参数下的旋转爆轰发动机进行了数值模拟与流动分析。数值结果显示，随着喷管喉道比的减小，旋转爆轰波依次呈现出稳定单波模态、单双波交替的混乱燃烧模态和爆燃燃烧模态。研究发现，喉道处产生的反射激波是影响RDW传播模态的关键因素。随着喉道比的减小，反射激波强度逐渐增强，并与新鲜来流混气作用引发局部热点，使单波模态转变为单双波交替的混乱燃烧模态；随着喉道比进一步减小，反射激波的高压作用使爆轰波熄爆，燃烧模态转变为爆燃燃烧。对推力性能的进一步分析表明，单波模态下发动机的推进性能随喉道比的减小而增强，且明显好于混乱模态和爆燃模态。

Abstract:

The propulsion performance of the rotating detonation engine （RDE） is related to the design of the back nozzle. In order to explore how the structure of the aerospike nozzle affects the combustion mode of rotating detonation wave and the propulsion performance of rotating detonation engine， the three-dimensional（3D） Euler equations coupled with hydrogen/air detailed mechanism is used as the governing equations and the rotating detonation engines with nozzles of different throat ratio have been simulated. The numerical results show that with the decreasing of the nozzle throat ratio parameter， the rotating detonation wave in chamber presents a stable single-wave combustion mode， a chaotic combustion mode with alternating single and double waves and a deflagration combustion mode in turn. It can be found that the reflected shock wave generated at the throat of nozzle is the key factor affecting the combustion mode. With the decreasing of throat ratio parameters， the intensities of the reflected shock wave increase gradually and a local hot spot is caused by mixing with fresh air flow， which is leading that combustion modes change from single-wave mode to the chaotic combustion mode in RDE. As the throat ratio further decreases， the pressures of reflected shock waves are higher， leading that the detonation waves in the chamber quench and the combustion mode changes to deflagration combustion. Through the analyses of the propulsion performance with different throat ratio parameters， it can be found that the thrust of RDE increases with the decreasing of the throat ratio， and the thrust in the single-wave combustion mode is better than that of the chaotic mode and the deflagration mode.