双凹腔超声速燃烧室煤油/氢气双燃料燃烧特性数值研究

Numerical research on combustion characteristics of kerosene/hydrogen dual fuels in a dual-cavity supersonic combustor

中文关键词: 超燃冲压发动机  圆截面燃烧室  双凹腔  双燃料  氢气当量比  燃烧性能

英文关键词: Scramjet engine  Circular cross-section combustor  Dual-cavity  Dual fuel  Hydrogen equivalence ratio  Combustion performance

中文摘要:

      针对超燃冲压发动机双凹腔燃烧室中煤油/氢气混合燃烧问题,煤油采用详细化学反应机理、氢气采用单步反应机理,对双凹腔间距(20-40mm)和氢气当量比(0.08-0.23)对燃烧过程的影响开展了数值研究。通过燃烧室温度、压力、释热率分布描述了燃烧组织状况,通过马赫数、湍动能、流线、涡量揭示了流场空间分布及掺混特征,阐述了氧气、二氧化碳、水的生成和分布机制,评估了总压损失系数、温度均匀性系数和燃烧效率的轴向分布情况。数值结果表明：减小间距可以增强双凹腔间掺混叠加作用,形成更强的剪切层涡结构,双凹腔间距20mm相比40mm燃烧效率整体提升约10%。随着氢气当量比提高,对火焰传播起到先增强后抑制作用,燃烧性能最好的氢气当量比为0.16。研究结果为双燃料燃烧室的设计提供了理论依据。

英文摘要:

      In order to solve the problem of kerosene/hydrogen mixed combustion in the dual-cavity combustor of scramjet, the detailed chemical reaction mechanism was used for kerosene and the single-step reaction mechanism was used for hydrogen, and numerical study was conducted to investigate the effects of dual cavity spacing (20-40mm) and hydrogen equivalence ratio (0.08-0.23) on the combustion process. The combustion organization was described by the temperature, pressure, and heat release rate distributions of combustion chamber. The spatial distribution and mixing characteristics of flow field were revealed by Mach number, turbulent kinetic energy, streamlines and vorticity. The generation and distribution mechanisms of oxygen, carbon dioxide, and water were elucidated, and the axial distributions of total pressure loss coefficient, temperature uniformity coefficient, and combustion efficiency were evaluated. The numerical results show that reducing the spacing can enhance the mixing stacking effect between the dual cavities, forming a stronger shear layer vortex structure. Compared to the spacing of 40mm between the dual cavities, the combustion efficiency is improved by about 10% of 20mm condition. As the hydrogen equivalence ratio increases, it first enhances and then suppresses the flame propagation, and the hydrogen equivalence ratio with the best combustion performance is 0.16. The research results provide a theoretical basis for the design of dual-fuel combustor.