Combustion flow field structure and performance in hydrogen-fueled scramjet
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摘要:
基于氢燃料单凹腔矩形截面超燃冲压发动机,在发动机入口马赫数为2的条件下,采用RANS(Reynolds-averaged Navier Stokes)方法求解包含10组分21步化学反应机理模型,并结合有限速率燃烧模型进行了数值模拟研究,并与试验数据进行对比。分析了无化学反应和化学反应流动条件下的燃烧室流场结构,研究了不同当量比对燃烧室燃烧性能的影响,考察了不同喷注位喷注氢气时的流场燃烧特性。结果表明:当量比的提高会使燃烧产物分布扩大并后移,发动机燃烧模态由超燃转为亚燃,发动机总压损失上升,燃烧效率降低,推力增加。在当量比为0.1~0.3时,在凹腔前端喷注燃料的发动机燃烧性能优于凹腔内喷注,当量比为0.4~0.5则相反。
Abstract:Based on the hydrogen-fueled single cavity rectangular cross-section scramjet, under the inflow condition of Mach number 2, the RANS (Reynolds-averaged Navier Stokes) method was used to solve the chemical mechanism model (10 species and 21 reactions), while the finite-rate combustion model was used to finish numerical simulation, and compared with the experimental data. The flow field structure of the combustor under nonreacting and reacting flow conditions was analyzed, then the effects of different equivalence ratios on the combustion performance of the combustor were discussed, and the combustion flow field characteristics of hydrogen injection at different injection positions were investigated. Results demonstrated that the distribution of combustion products was expanded and also moved back with the increase of equivalence ratio, changed the engine combustion mode from supersonic combustion to subsonic combustion, increased the total pressure loss, decreased the combustion efficiency and augment the thrust. At 0.1 to 0.3 equivalent ratios, the scramjet combustion performance of fuel injected at the front of the cavity was better than that injected in the cavity, which was contrary to 0.4 to 0.5 equivalent ratios.
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Key words:
- scramjet /
- hydrogen /
- combustion efficiency /
- equivalence ratio /
- total pressure loss
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表 1 无化学反应流动数值计算结果与试验值比较
Table 1. Comparison between experimental values and numerical simulation
参数 试验值 计算值 相对误差/% 监测点1壁面压力/MPa 0.103 0.109 5.83 监测点2壁面压力/MPa 0.101 0.103 1.98 监测点1壁面切应力/Pa 825 770 −6.67 监测点2壁面切应力/Pa 401 382 −4.74 表 2 出口处燃烧效率
Table 2. Combustion efficiency of outlet
φ J1 J2 0.1 0.888 0.899 0.2 0.689 0.844 0.3 0.784 0.791 0.4 0.721 0.715 0.5 0.626 0.605 -
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