Accident release of superheated liquid could produce a violent phase change and trigger a highly destructive flashing jet. In this work, release experiments are performed using a 20 L tank and transparent nozzles, with water as the fluid throughout. The experimental conditions included storage temperature ( = 100-160 °C), storage pressure ( = 6-16 bar), and nozzle sizes ( = 1-6 mm). High-speed image processing and capacitive void fraction sensor are used to quantify the two-phase flow of superheated liquid inside the nozzle and the downstream jet break-up regimes. The experimental results show that void fraction () goes through three phases during the release process: growth, stabilization and decay. It is also demonstrated that bubble nucleation, growth and burst determine the breakup of the downstream jet. The and are the main factors affecting the , while the only change the release rate. Moreover, it is verified that none of the existing flashing criteria () can accurately determine the boundary conditions of the flashing regimes. Instead, the parameters characterizing bubbles nucleation and growth, α, can unify the effects of (, , and ) to determine the physical mechanism of the flashing process. In this work, a novel method to distinguish between external flashing ( = 0), internal flashing (0 < ≤ 25) and full flashing ( > 25), and a steady-state model = () is developed for the flashing jet.

中文翻译：

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透明喷嘴过热液体释放的喷嘴内流动及其对外部闪蒸射流的影响

过热液体的意外释放可能会产生剧烈的相变并引发极具破坏性的闪光喷射。在这项工作中，使用 20 L 水箱和透明喷嘴进行释放实验，整个过程以水为流体。实验条件包括储存温度 (= 100-160 °C)、储存压力 (= 6-16 bar) 和喷嘴尺寸 (= 1-6 mm)。高速图像处理和电容式空隙率传感器用于量化喷嘴内过热液体的两相流和下游射流破碎状态。实验结果表明，空隙率（）在释放过程中经历了三个阶段：增长、稳定和衰减。还证明了气泡的成核、生长和破裂决定了下游射流的破裂。和 是影响 的主要因素，而唯一改变的是释放速率。此外，经验证，现有的闪蒸判据（）均不能准确确定闪蒸状态的边界条件。相反，表征气泡成核和生长的参数 α 可以统一 (、 和 ) 的影响来确定闪蒸过程的物理机制。在这项工作中，一种区分外部闪蒸（= 0）、内部闪蒸（0 < ≤ 25）和完全闪蒸（> 25）的新方法，以及闪蒸射流的稳态模型=（）。