The series of nine Jack Rabbit II (JR II) chlorine release field experiments in 2015 and 2016 involved releases of pressurized liquefied chlorine from tanks containing 5–20 tons of liquid. This paper concerns JR II Trial 8, where the release hole (15.2 cm diameter) was oriented upwards at the top of the tank. To our knowledge, this is the only full-scale vertically-directed release of pressurized liquefied chlorine that is available for detailed analysis. Our aim is to improve understanding of the characteristics of the dense jet trajectory (e.g., maximum plume rise, downwind distance where the dense plume first touches the ground, and maximum concentration at touchdown). The chlorine emission rate was measured by instruments in the tank, and the plume rise geometry was estimated from photographs, videos, and lidar scans taken from several angles. During the first 10 s of the release, the videos show that the dense jet rises up to about 40 m, then sinks towards the ground, touching down at a distance of about 60 m. The portion of the plume that sinks to the ground then spreads out about 30–40 m in all directions due to gravity slumping. Due to the decrease with time of the momentum jet mass release rate, the jet gradually becomes less dense and less powerful and the plume remains aloft after about 30–60 s. However, the dense cloud that touched down in the early phases moves downwind as a typical dense cloud. The observed dense jet plume rise and touchdown distance are shown to approximately agree within about a factor of two with integral model predictions by 1) the analytical dense gas plume formulas suggested for vertical jets in 1973 by Hoot, Meroney, and Peterka (HMP), 2) the analytical formula for buoyant (positive or negative) plume trajectory suggested by Briggs in 1969, and 3) the DRIFT dispersion software, which is an integral model. Also, HMP and DRIFT model predictions of concentration at touchdown agree with Trial 8 observations within a factor of about two. It is concluded that the dense jet plume models are able to simulate the Trial 8 plume trajectory and ground level maximum concentration within acceptable ranges (i.e., most of time, within a factor of two).

2015 年和 2016 年的九次 Jack Rabbit II (JR II) 氯释放现场试验系列涉及从装有 5-20 吨液体的储罐中释放加压液化氯。本文涉及 JR II 试验 8，其中释放孔（直径 15.2 厘米）在油箱顶部朝上。据我们所知，这是唯一可用于详细分析的加压液化氯的全面垂直定向释放。我们的目标是提高对密集喷射轨迹特征的理解（例如，最大羽流上升、密集羽流首先接触地面的顺风距离以及着陆时的最大浓度）。氯气排放率是通过罐中的仪器测量的，羽流上升几何形状是根据从多个角度拍摄的照片、视频和激光雷达扫描来估计的。在发布的前 10 秒内，视频显示密集的喷流上升到约 40 m，然后向地面下沉，在约 60 m 的距离着陆。由于重力下沉，下沉到地面的羽流部分然后向各个方向扩散约 30-40 m。由于动量射流质量释放率随时间降低，射流的密度和强度逐渐降低，羽流在大约 30-60 秒后仍保持在高空。然而，早期降落的密集云作为典型的密集云顺风移动。观察到的密集喷射羽流上升和着陆距离与积分模型预测结果近似一致，大约为 2 倍，1) Hoot、Merony 和 Peterka (HMP) 在 1973 年为垂直喷射建议的分析密集气体羽流公式，2) Briggs 在 1969 年提出的浮力（正或负）羽流轨迹的解析公式，以及 3) DRIFT 扩散软件，这是一个积分模型。此外，HMP 和 DRIFT 模型对着陆时浓度的预测与试验 8 的观察结果一致，系数约为 2。得出的结论是，密集喷射羽流模型能够模拟试验 8 羽流轨迹和在可接受范围内的地面最大浓度（即，大部分时间，在两倍以内）。