Abstract

The two-phase slug flow, or the Taylor flow, is used in a variety of applications, including efficient heat transfer in pulsating heat pipes (PHPs). The heat transfer efficiency is due to the presence of liquid thin film surrounding the bubble and separating it from the hot wall. The thin film facilitates much faster heat dissipation by evaporation as compared with single-phase cooling. The thinness of the liquid film also creates significant difficulty for numerical simulation of Taylor bubbles, and the lower is the bubble velocity, the thinner is the liquid film. We carried out a 3D simulation of the hydrodynamics and heat transfer during motion of Taylor bubbles of gas in a capillary tube with a diameter of 2 mm in the velocity range of 0.05–0.5 m/s, resolving the near-wall region in detail. The distributions of the friction coefficient and heat flux on the wall along the bubble motion were obtained. It was shown that complex cascade recirculation zones appeared near the bubble and led to significant change in both shear stresses and heat flux near the wall as compared with a single-phase flow.

中文翻译：

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泰勒流中流体动力学和传热的 3D 数值模拟

摘要

两相段塞流或泰勒流用于多种应用，包括脉动热管 (PHP) 中的高效传热。传热效率是由于存在围绕气泡并将其与热壁隔开的液体薄膜。与单相冷却相比，薄膜通过蒸发促进了更快的散热。液膜的薄度也给泰勒气泡的数值模拟带来了很大的困难，气泡速度越低，液膜越薄。我们对直径为 2 mm、速度范围为 0.05-0.5 m/s 的毛细管中的泰勒气泡运动过程中的流体动力学和传热进行了 3D 模拟，详细解析了近壁区域。得到了壁面摩擦系数和热通量沿气泡运动的分布。结果表明，与单相流相比，气泡附近出现复杂的级联再循环区，导致壁附近的剪切应力和热通量发生显着变化。