Abstract A new injection strategy combined with a micro-ramp and an air porthole is proposed in this paper, and the properties of the transverse gaseous injection flow field with such injection strategy have been investigated simultaneously. The numerical approach employed in the current study has been validated against the two-dimensional and three-dimensional experimental data in the open literature, and it can be used with confidence to investigate the influence of the air porthole aspect ratio and the distance between the air porthole and the fuel orifice on the transverse injection flow field with the combination of a micro-ramp and an air porthole. The obtained results predicted by the three-dimensional Reynolds-average Navier–Stokes (RANS) equations coupled with the two equation k-ω shear stress transport (SST) turbulence model show that the mixing performances of the transverse gaseous injection flow fields vary under different conditions, and a transverse injection flow field with short mixing length, low stagnation pressure loss and ideal fuel penetration depth has been achieved by adding the combination of an optimized micro-ramp with a proper air porthole, i.e. Case 6–8, and its mixing length decreases considerably by 14.26 mm on the basis of Case c, even shorter than the mixing length of Case a by 2.86 mm. However, its total pressure loss increases when compared with Case c, and its stagnation pressure loss is 2.7 percent smaller than Case a. Further, the hydrogen distribution on the flat plate of Case 6–8 is much less than that of Case a and Case b. Additionally, it is found that the mixing enhancement mechanism of the air jet is different from that of the micro-ramp. The micro-ramp enhances the mixing process between the fuel and air by inducing large-scale vortices, while the air porthole enhances the mixing process by seeding lots of air into the fuel boundary layer, as well as fuel plume.

中文翻译：

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横向注气流场中微坡道与气孔组合引起的混合改进

摘要 本文提出了一种结合微坡道和气孔的注入策略，并同时研究了这种注入策略下横向气体注入流场的特性。当前研究中采用的数值方法已针对公开文献中的二维和三维实验数据进行了验证，可以放心地用于研究空气舷窗纵横比和空气之间的距离的影响。横向喷射流场上的舷窗和燃料孔，微坡道和空气舷窗相结合。三维雷诺平均 Navier-Stokes (RANS) 方程结合两个方程 k-ω 剪切应力传递 (SST) 湍流模型预测的结果表明，横向注气流场的混合性能在不同的通过添加优化的微坡道和适当的空气舷窗的组合，即案例 6-8 及其混合，实现了具有短混合长度、低停滞压力损失和理想燃料穿透深度的横向喷射流场长度在案例 c 的基础上大大减少了 14.26 毫米，甚至比案例 a 的混合长度短了 2.86 毫米。但其总压力损失与情况 c 相比有所增加，滞流压力损失比情况 a 小 2.7%。更多，案例 6-8 平板上的氢分布远小于案例 a 和案例 b。此外，发现空气射流的混合增强机制与微斜坡的混合增强机制不同。微坡道通过引起大规模涡流来增强燃料和空气之间的混合过程，而空气舷窗通过将大量空气以及燃料羽流注入燃料边界层来增强混合过程。