Abstract The hydrogen-fueled range extender based on the rotary engine is a promising solution for battery electric vehicles due to key advantages such as: high efficiency, small packaging dimensions and low weight within the framework of the near zero-emission concept. Although rotary engine has been examined over the past years, the detailed knowledge of hydrogen combustion in the rotary engine with direct injection system has not been investigated properly. In this paper, the rotary range extender was numerically studied with a focus on the influence of the direct multiple injection strategies on hydrogen distribution and combustion. The result demonstrates that due to large flame speed and diffusion length the engines fueled by pure hydrogen differ significantly from the engines with conventional fuel. The process is characterized by the weak influence of turbulence on the flame during almost the whole combustion stroke except for the late stages when 70% of the fuel is already burnt. Hence the difference in the injection strategies lead to different local hydrogen distribution that has effects on combustion rate and performance characteristics significantly. Fuel stratification leads to the formation of subregions with various hydrogen concentration. The lean mixture cannot provide enough high temperature, whereas the rich mixture is characterized by a lack of oxygen. The total NOx formation can be twice lower in comparison with premixed combustion at the same averaged equivalence ratio. The direct multiple injection strategy allows the use of a higher averaged equivalence ratio up to 0.8 which results in larger power density in combination with low NOx emission.

中文翻译：

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多种燃料喷射策略对纯电动汽车氢燃料旋转增程器混合气形成和燃烧的影响

摘要 基于转子发动机的氢燃料增程器在近零排放概念的框架内具有效率高、封装尺寸小和重量轻等关键优势，是电池电动汽车的有前途的解决方案。尽管过去几年对转子发动机进行了研究，但对直喷系统转子发动机中氢气燃烧的详细知识还没有进行适当的研究。在本文中，对旋转式增程器进行了数值研究，重点是直接多次喷射策略对氢气分布和燃烧的影响。结果表明，由于火焰速度和扩散长度大，纯氢发动机与传统燃料发动机有很大不同。该过程的特点是几乎在整个燃烧冲程中湍流对火焰的影响很小，除了后期阶段，70%的燃料已经燃烧。因此，喷射策略的不同导致不同的局部氢分布，这对燃烧率和性能特性有显着影响。燃料分层导致形成具有不同氢浓度的子区域。稀混合气不能提供足够高的温度，而富混合气的特点是缺氧。与相同平均当量比的预混燃烧相比，NOx 的总形成量可以低两倍。直接多次喷射策略允许使用高达 0 的更高平均当量比。