Hydrogen as a fuel is feasible for future sustainable mobility. Because hydrogen has a low volumetric energy density, high-pressure hydrogen is required for high-speed fuel injection. The objective of this research is analysis of the hydrogen spray behavior depending on the ambient pressure. A high-pressure (10 MPa) hydrogen spray is visualized in a constant volume combustion chamber in which the ambient pressure and injection duration are varied. The schlieren method is utilized to capture the hydrogen spray with a high-speed camera. The characteristics of the hydrogen hollow-cone spray are investigated using high-speed spray images. High ambient pressure decreases the vertical extent of the spray penetration and its area. The centroid of the spray is contracted toward the axis of the injector until the ambient pressure reaches 2.0 MPa, and the pressure difference between the inner and outer sections of the spray is larger for high ambient pressures. At high ambient pressure, the heterogeneity of the hydrogen mixture increases. Owing to the aerodynamic effect, the contracted spray reconstructs the main hydrogen plume at the center of the injector. Moreover, hydrogen travels toward the top of the injector because of the generation of a vortex at the inner side of the spray. Based on the findings, hydrogen direct injection can contribute to sustainable mobility in the future.

氢作为燃料对于未来的可持续出行是可行的。由于氢气的体积能量密度低，因此需要高压氢气进行高速燃料喷射。这项研究的目的是根据环境压力分析氢喷雾行为。在恒定体积的燃烧室中观察到高压（10 MPa）氢喷雾，在该燃烧室中，环境压力和喷射持续时间发生了变化。schlieren方法用于通过高速相机捕获氢喷雾。使用高速喷雾图像研究了氢空心锥喷雾的特性。高环境压力会降低喷雾渗透的垂直范围及其面积。喷雾的质心朝着喷油器的轴方向收缩，直到环境压力达到2.0 MPa，对于较高的环境压力，喷雾内部和外部之间的压力差更大。在高环境压力下，氢混合物的异质性增加。由于空气动力学的作用，收缩的喷雾在喷射器的中心重建了主要的氢羽。此外，由于在喷雾的内侧产生涡流，氢向喷射器的顶部行进。基于这些发现，氢直接注入可以为未来的可持续交通做出贡献。此外，由于在喷雾的内侧产生涡流，氢向喷射器的顶部行进。基于这些发现，氢直接注入可以为未来的可持续交通做出贡献。此外，由于在喷雾的内侧产生涡流，氢向喷射器的顶部行进。基于这些发现，氢直接注入可以为未来的可持续交通做出贡献。