The flow and thermohydraulic characteristics of an atmospheric-pressure argon arc jet plume injected into water were investigated. The temperature of the underwater plasma plume was measured using optical emission spectroscopy, and the water with a thermocouple. The velocity field of the water induced by the arc-jet injection was observed using the particle image velocimetry method, which demonstrated that as the discharge current increased, the water flow velocity also increased. The diameter of the plasma plume was observed to be approximately the same as that of the anode nozzle, 6.7 mm. The heat transfer characteristics of the injected arc jet plume to the surrounding water were also investigated. The average velocity of the arc jet plume in the water was estimated based on mass balance to be in the range of 280–2500 m/s as a monotonically decreasing function of the flow distance. The velocity of the underwater arc is found to be subsonic over the entire volume of the plasma plume, however, it is larger than the sound velocity of the water up to 10 mm downward from the plasma nozzle. The resultant Reynolds number of the plasma flow was found to be between 1000 and 2800, indicating the flow was turbulent only at the most upstream region up to 3 mm downward from the nozzle, while it was almost laminar over the whole observed area of the underwater arc plasma plume. The heat transfer characteristics were discussed in terms of the dimensionless numbers. The Nusselt number ranges from approximately ∼3.8 to ∼6.5, which is a reasonable value. Although the existing theories of correlation heat transfer cannot fully explain the relationship between these dimensionless numbers, the correlation proposed by Fiszdon and the one by Lee–Pfender can qualitatively explain the observed results for the upstream region, which include the effects of the variation in the mass density, the viscosity, and the specific heat for a constant pressure of the argon arc plasma. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

中文翻译：

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电弧放电氩等离子羽流注入水中的传热和热工水力特性

研究了注入水中的大气压氩弧射流羽流的流动和热水力特性。水下等离子体羽流的温度使用光学发射光谱测量，水的温度使用热电偶测量。采用粒子图像测速法观察了电弧射流注入水的速度场，表明随着放电电流的增加，水的流速也随之增加。观察到等离子体羽流的直径与阳极喷嘴的直径大致相同，为 6.7 毫米。还研究了注入的电弧射流羽流到周围水的传热特性。基于质量平衡估计水中电弧射流羽流的平均速度在 280-2500 m/s 的范围内，作为流动距离的单调递减函数。发现水下电弧的速度在等离子体羽流的整个体积上是亚音速的，但是，它大于从等离子体喷嘴向下最多 10 毫米的水的声速。所得等离子体流的雷诺数在 1000 到 2800 之间，表明仅在距喷嘴向下 3 毫米的最上游区域流动是湍流，而在整个水下观察区域几乎是层流弧等离子羽流。用无量纲数讨论了传热特性。Nusselt 数的范围从大约 ∼3.8 到 ∼6.5，这是一个合理的值。尽管现有的相关传热理论不能完全解释这些无量纲数之间的关系，但 Fiszdon 提出的相关性和 Lee-Pfender 提出的相关性可以定性地解释上游区域的观测结果，其中包括氩弧等离子体恒压下的质量密度、粘度和比热。© 2022 日本电气工程师学会。由 Wiley Periodicals LLC 出版。以及氩弧等离子体恒压的比热。© 2022 日本电气工程师学会。由 Wiley Periodicals LLC 出版。以及氩弧等离子体恒压的比热。© 2022 日本电气工程师学会。由 Wiley Periodicals LLC 出版。