Development of optimum cooling systemn of water spraying for a high temperature metal

我们相信，这项研究的最初预期目的大部分已经达到。本研究基本上涵盖了计算流体力学、两相流理论、传热学和数值分析等几个特殊领域，因此本研究分为三个阶段。首先，系统地分析了由空气和水滴组成的两相混合物的喷嘴流动、两相自由射流的流动机理以及两相自由射流冲击平板的流动行为。然而，尽管许多研究人员提出了挑战，但液滴撞击平板的变形过程仍未被阐明。为此，本课题组建立了评价变形过程的数值模型。经验证，用本模型计算的变形过程与…吻合较好更多的是实验数据。与这一结果有关的论文已提交给TRANS。第二，从实验上阐明了液滴撞击莱登弗罗斯特点以上热板表面的变形行为可以分为三种类型。根据液滴与平板表面碰撞后是否破碎，液滴的变形行为基本上可以分为两种模式。考虑到液滴的形状在液滴不破碎的情况下，似乎有三种模式。液滴是否破碎的条件不仅取决于We数，还取决于表面温度和性质等。同时，虽然不是理论上的，而是经验的，但我们阐明了每种型式的挤压变形的总体机理。第三，考虑了对超过莱登弗罗斯特温度的热板表面喷水冷却过程的估计，从而为连铸过程中二冷区的实际操作提供了冷却强度的评估。为此，对高温金属表面进行了多种不同水流量的喷水冷却，并用CA热电偶测量了每个温度随时间的变化过程。通过逆分析，建立了热板喷水冷却过程的预测模型。最后，我们认为仍有许多问题有待解决，希望能对本研究起到推动作用。较少

We believe that the intially anticipated purpose of this research has been attained for the most part. This research basically covers a few special fields such as computational fluid dynamics, two-phase flow theory, heat transfer and numerical analysis, and therefore the research consists of the three stages. The results obtained here are summarized as follows :First, the nozzle frow of a two-phase mixture composed of air and water droplets, the flow mechanism of the two-phase free jet and the flow behavior of the two-phase freejet impinging on a flat plate have been unmerically analyzed. However, the deformation process of droplets impinging even a flat plate with an ordinary room temperature has not yet been clarified regardless of the challenge of many researchers. Hence, the numerical model to assess the deformation process has been established by our research group. Also, it has been confirmed that the deformation process calculated by the present model is in fairly good agreement … More with experimental data. The paper concerned with this result has been submitted to the Trans. ASME Journal of Fluids Engineering for publication.Second, it has been experimentally clarified that the deformation behavior of droplets impinging on a hot plate surface beyond the Leidenfrost point can be classified into three kinds of patterns. Basically, the droplet deformation behavior may be classified into two kinds of patterns according to whether the droplet crushes or not after the collision with the plate surface. Taking into account the configuration of droplet of the case where the droplet does not crush, there seems to be three kinds of patterns. The condition whether the droplet crushes or otherwise is dependent not only upon the We number, but also upon the surface temperature and properties etc.. Also, we have clarified the overall mechanism of the crushed and deformation for each pattern, although it is not theoretical but empirical.Third, the estimation of cooling process of a hot plate surface beyond the Leidenfrost temperature by water spray have considered so that the assess of the cooling intensity is available for an actual operation in the secondary cooling zone of the continuous casting process. In order to do so, the high temperature metal surface has been cooled by many kinds of water sprays of which the water flow rate is entirely different from each other and each temperature process with time has been measured by the CA thermocouples. Thereby, the predictable modeling for cooling process of a hot plate by a water spray has been constructed by the inverse analysis.Finally, we think that there are a number of problems which remains unsolved and wish to promote the present investigation further. Less