Hydrogen's wide flammability range causes its high-pressure jet flames to exhibit large-scale, high-temperature characteristics, posing risks of casualties and property damage. This study investigates the impact of different nozzle shapes and release pressures on flame behavior and temperature distribution through high-pressure hydrogen jet flame experiments. Circular outlets (0.5–4 mm diameter) and rectangular outlets (aspect ratios 1 to 8) are used, covering release pressures from 20 to 220 bar. High-pressure hydrogen is released through a nozzle into ambient air, igniting to form a flame. Flame length, width, and axial temperature are measured. Findings indicate that visible flame size increases with release pressure. The models for dimensionless visible flame length and width, considering the dimensionless heat release rate, are proposed for different nozzle shapes. Additionally, the dimensionless temperature rise along the flame axis is observed to be a function of the dimensionless distance and dimensionless heat release rate.

中文翻译：

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不同出口形状氢气射流火焰行为及温度分布实验研究

氢气的可燃范围较广，导致其高压射流火焰表现出大范围、高温的特性，存在造成人员伤亡和财产损失的风险。本研究通过高压氢气喷射火焰实验研究了不同喷嘴形状和释放压力对火焰行为和温度分布的影响。使用圆形出口（直径 0.5–4 mm）和矩形出口（纵横比 1 至 8），覆盖 20 至 220 bar 的释放压力。高压氢气通过喷嘴释放到周围空气中，点燃形成火焰。测量火焰长度、宽度和轴向温度。研究结果表明，可见火焰尺寸随着释放压力的增加而增加。针对不同的喷嘴形状，考虑了无量纲热释放率，提出了无量纲可见火焰长度和宽度的模型。此外，观察到沿火焰轴的无量纲温升是无量纲距离和无量纲热释放速率的函数。