Air-fuel mixing in a SCRAMJET engine is augmented by the interaction of the transverse fuel jet with the incoming supersonic air. The strong bow shock created by this interaction aids in mixing and increases the fuel residence time, but it also leads to loss in performance of the SCRAMJET engine through the loss of stagnation pressure, and rise in entropy in the combustor. One of the ways to address this issue is to weaken the bow shock by changing the angle of injection of fuel into the combustor. In the present study, the effect of variation of the injection angle, measured in the direction of the cross-flow from a line perpendicular to it (and the wall), has been numerically studied and analyzed on a 3-D SCRAMJET combustor of generic design with dual injectors, using Menter's SST model for turbulence on an in-house 3-D unstructured grid RANS solver. The angle for each injector is independently varied between 0° and 45° with an increment of 15°, while the jet positions are kept fixed at locations previously found to be optimum for the chosen flow conditions and zero angle (i.e. transverse) injection. It is observed that in every case that positive non-zero angles of injection, in the direction of the crossflow, increase thermodynamic efficiency, while the negative non-zero angles, opposing the crossflow, augment mixing. As mixing is of paramount importance in the SCRAMJET engine, due to high speeds and low residence times, we conclude that the best option is to have the angle of fuel jet injection in the direction opposing the incoming flow – a recommendation that has not been seen yet in the research literature. The degree to which the injection is slanted towards the incoming flow can be decided on the basis of the desired rate of the simultaneous penetration of the fuel into the recirculating flame-holder, which increases with increasing angle.

横向燃料射流与进入的超音速空气的相互作用增强了SCRAMJET发动机中的空气燃料混合。这种相互作用产生的强烈的弓形冲击有助于混合并增加燃料停留时间，但同时也会由于停滞压力的损失而导致SCRAMJET发动机性能的损失，并使燃烧室的熵增加。解决该问题的方法之一是通过改变燃料向燃烧器的喷射角度来减弱船首冲击。在本研究中，已经在通用的3-D SCRAMJET燃烧器上进行了数值研究和分析了在与垂直线（和壁）垂直的横流方向上测量的喷射角变化的影响。使用Menter'设计双喷油器 内部3D非结构化网格RANS求解器上的SST湍流模型。每个喷油嘴的角度独立地在0°和45°之间以15°的增量变化，而射流位置保持固定在先前发现的位置，该位置对于选定的流动条件和零角度（即横向）喷油来说是最佳的。可以观察到，在每种情况下，在错流方向上正的非零喷射角都会增加热力学效率，而与错流相反的负的非零喷射角会增加混合。由于高速和短停留时间在SCRAMJET发动机中至关重要，因此我们得出结论，最好的选择是使燃油喷射的喷射角度与流入方向相反，这是目前尚未发现的建议在研究文献中。