High momentum release of jet fire can be very intense, and the released heat can be very high, depending on the source capacity. One of the key parameters in characterizing the jet fire is the radiative fraction. The previous study has correlated the radiative fraction to the source using a Froude number basis. Nevertheless, the flame mechanism and associated geometrical features gave significant effects on the global radiative heat flux to some extent. Therefore, the characterization of the main geometrical features, particularly on jet flame structures at higher momentum release conditions and its correlation with the radiative fraction, are valuable to be investigated. In this work, propane was used as fuel and released through a 9.8 mm circular nozzle with the exit velocities were set ranging between 27 and 65 m/s. It was found that the liftoff length estimation from this work is in a good agreement with the jet fire release under sub‐atmospheric pressure in a vertical orientation. Furthermore, the flame projected length and height were characterized by momentum‐driven length (L m) and buoyancy‐driven height (L b) by the dimensionless characteristics length (Ʌ). The experimental observations indicate that as the Ʌ ≥ 0.0001, the radiative fraction shows a decreasing trend.

中文翻译：

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水平浮力喷射火的主要几何特征及相关辐射率

喷射火的高动量释放可能非常强烈，释放的热量可能非常高，这取决于源容量。表征喷射火的关键参数之一是辐射分数。先前的研究使用弗劳德数基础将辐射分数与源相关联。尽管如此，火焰机制和相关的几何特征在一定程度上对全球辐射热通量产生了显着影响。因此，主要几何特征的表征，特别是在较高动量释放条件下的喷射火焰结构及其与辐射分数的相关性，是值得研究的。在这项工作中，丙烷用作燃料并通过 9.8 毫米圆形喷嘴释放，出口速度设置在 27 到 65 m/s 之间。发现从这项工作中估计的升空长度与垂直方向的亚大气压下的喷射火释放非常吻合。此外，火焰投射长度和高度由动量驱动长度（L m）和浮力驱动高度（L b）由无量纲特征长度（Ʌ）表征。实验观察表明，随着Ʌ ≥ 0.0001，辐射分数呈下降趋势。