基于纹影法在定容喷射装置上进行了不同喷射压力、环境压力下的氢气射流特性试验，研究外开式喷嘴的氢气射流特性及喷射参数的变化规律。结果表明：氢气射流近场呈现锥形结构，且形成了喷射轨迹线，而射流远场逐渐发展成大尺度球形涡流结构。喷射压力增大，轴向和径向贯穿距离增大而卷吸率减小；背景压力增大，轴向和径向贯穿距离减小而卷吸率增大；射流锥角的变化与喷射压力或背景压力关系不大，但随喷射时间逐渐从80°变小并趋于22°。另外通过归一化分析发现，贯穿距离在不同边界条件下均具有较好的自相似性，自相似系数(x/y)逐渐趋于0.59左右，径向扩散性优于单孔喷嘴氢气射流。合理利用氢气射流特性可以优化直喷氢内燃机的混合气形成，为外开式喷嘴的喷射策略优化提供依据。

Based on the schlieren method, the characteristics of hydrogen jets were tested on a constant volume injection device under different injection pressures and ambient pressures. The hydrogen jet characteristics of outward-opening nozzles and the variation laws of injection parameters were studied. The results show that the near-field of hydrogen jet presents a conical structure and forms a jet trajectory and the far-field of jet gradually develops into a large-scale spherical vortex structure. With the increase of jet pressure, axial and radial penetration distances increase and entrainment rate reduces; while increasing background pressure will show the opposite trend. The jet cone angle gradually decreases from 80° and becomes stable at close to 22°, and willnot be affected by jet pressure or background pressure. According to the normalization analysis, it is found that the penetration distance has a good self-similarity under different boundary conditions and the self-similarity coefficient (x/y) gradually approaches about 0.59. The radial diffusivity is also better than that of single-hole nozzle. Reasonable use of hydrogen jet characteristics can optimize the mixture formation of direct injection hydrogen engine, which provides a basis for the injection strategy optimization of outward-opening nozzle.