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本文从换热器管束中最基本的串列布置形式出发研究处于过渡流区域的小管径换热器的性能变化。通过基于作者研究开发的复合网格计算方法模拟了在低、中雷诺数条件下,串列双圆柱随中心距的变化下的流场、温度场的变化特性,并分析了其机理。计算结果表明,随着圆柱间中心距的逐渐增大,圆柱尾流呈现出从不稳定到稳定再到不稳定的变化规律。通过研究发现,两圆柱中间流场是否稳定与这一区域的u_m是否是连续的负值有着密切的关系,而流场的变化规律同两圆柱间的u_m的变化规律也十分相似。
In this paper, we study the change of performance of the small-diameter heat exchanger in the transitional flow region based on the most basic series arrangement in the heat exchanger tube bundle. The characteristics of the flow field and the temperature field under the conditions of low and medium Reynolds number and the change of the tandem double tandem with the center distance were simulated by the composite grid method based on the author’s research and development. The mechanism was also analyzed. The calculation results show that with the increasing of the center distance between the cylinders, the wake variation of the cylinder presents a change from unstable to steady to unstable. Through the research, it is found that whether the flow field in the middle of the two columns is stable or not is closely related to whether the u_m in this area is a continuous negative value. The variation law of the flow field is also very similar to that of u_m between two cylinders.