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首页> 外文期刊>International Journal of Heat and Mass Transfer >Analytical and computational methodology for modeling spray quenching of solid alloy cylinders
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Analytical and computational methodology for modeling spray quenching of solid alloy cylinders

机译：固体合金气缸喷雾淬火建模的分析和计算方法

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摘要

Heat-treating of solid alloy cylinders is an important practical problem for which no optimal production methods have been developed, especially in terms of the most crucial quenching stage. This study explores the use of spray quenching as an alternative to the commonly used bath quenching, which is known to yield relatively slow quench rates and provide few options for spatial optimization of cooling rate. A carefully configured spray cooling system is examined, which provides maximum coverage of the surface of a solid alloy cylinder with full-cone pressure sprays. A new analytical model is derived to determine the shape and size of the spray impact zone, as well as the distribution of volumetric flux across the curved surface of the cylinder. This distribution is combined with heat transfer correlations for all spray boiling regimes to generate a local boiling curve for every location across the impact surface. Using these boiling curves as boundary conditions, a transient analysis is conducted for aluminum alloy and steel cylinders. Increasing the nozzle pressure drop or decreasing the orifice-to-surface distance are shown to hasten the exit from the poor film boiling regime to the more efficient transition boiling regime, resulting in a quicker quench. Relatively high thermal diffusivity causes faster transmission of the spray cooling effect through the cylinder and milder temperature gradients in aluminum compared to steel. This also causes the outer surface to cool earlier but deeper points much slower for steel. Large temperature gradients are encountered on the surface during the quench because of different boiling regimes occurring at different locations exposed to the spray. This study highlights several practical advantages of spray quenching compared with bath quenching, including the ability to achieve a wide range of fast quench rates, uniformity and predictability of quench rate, and the ability to predict and guard against imperfections caused by thermal stresses.
机译：固态合金钢瓶的热处理是一个重要的实际问题，尚未开发出最佳的生产方法，特别是在最关键的淬火阶段。这项研究探索了使用喷雾淬火作为常用浴淬火的替代方法，众所周知，该方法可产生相对较慢的淬火速度，并且很少提供冷却速度空间优化的选择。检查了精心配置的喷雾冷却系统，该系统使用全锥压力喷雾可最大程度地覆盖固态合金圆柱体的表面。导出了一个新的分析模型来确定喷雾冲击区的形状和大小，以及在圆柱体曲面上的体积通量分布。该分布与所有喷雾沸腾状态的传热相关性结合在一起，以生成冲击表面上每个位置的局部沸腾曲线。使用这些沸腾曲线作为边界条件，对铝合金和钢瓶进行了瞬态分析。增大喷嘴压降或减小孔与表面的距离，可以加快从不良薄膜沸腾状态到更有效的过渡沸腾状态的出口，从而加快淬火速度。与钢相比，相对较高的热扩散率会导致喷雾冷却效果更快地通过气缸传递，并且铝中的温度梯度更缓和。这也会导致外表面较早冷却，但较深的点则较慢。在淬火过程中，由于暴露在喷雾中不同位置的沸腾方式不同，在表面上会遇到较大的温度梯度。这项研究强调了与浴淬火相比，喷雾淬火的一些实际优势，包括能够实现各种快速淬火速率，淬火速率的均匀性和可预测性，以及预测和防止由热应力引起的缺陷的能力。

著录项

  • 来源
    《International Journal of Heat and Mass Transfer》 |2010年第26期|p.5871-5883|共13页
  • 作者

    Nikhin Mascarenhas; Issam Mudawar;

  • 作者单位

    Boiling and Two-phase Flow Laboratory (BTPFL), School of Mechanical Engineering. Purdue University, West Lafayette, IN 47907, USA;

    Boiling and Two-phase Flow Laboratory (BTPFL), School of Mechanical Engineering. Purdue University, West Lafayette, IN 47907, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    quenching; heat diffusion; spray cooling;

    机译：淬火热扩散喷雾冷却;

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