首页> 外文期刊>International Journal of Heat and Mass Transfer >Experimental investigation of spray impingement hydrodynamic on a hot surface at high flow rates using phase Doppler analysis and infrared thermography
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Experimental investigation of spray impingement hydrodynamic on a hot surface at high flow rates using phase Doppler analysis and infrared thermography

机译:相位多普勒分析和红外热成像技术在高流速下对热表面喷射冲击水动力的实验研究

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摘要

Large panels of studies have been performed in order to investigate the dynamic behavior of a droplet during the impingement onto a rigid wall. Most of them are dealing with single droplets and only fewer are devoted to sprays, for which several diagnostics were implemented. Moreover, when sprays are involved, the liquid mass flux is generally quite low (on the order of several kg/m~2/s) and the case of a cold surface was mainly considered. Therefore, the present experimental work aims at investigating the impingement of sprays onto hot surfaces (up to 800 ℃) with liquid mass flux up to 13 kg/m~2/s. Specifically, the main objective is to characterize the secondary droplets as a function of the surface temperature, starting from the Leidenfrost regime. To that purpose, a 2D phase Doppler analyzer (PDA) is synchronized with an infrared camera in order to measure simultaneously the time evolution of the local droplets size and velocity distributions with the surface temperature. Six full cone sprays were used in order to obtain a wide range of impingement conditions (normal incident Weber and liquid mass flux). A comparison of the impingement characteristics is also performed when the surface remains at room temperature. Another important point concerns also the effect on the spray flow of the presence of the surface. Results show clearly that the incident droplet trajectories are modified by the presence of the solid wall itself and depend strongly on the temperature surface. The in-depth investigation of the impingement characteristics of the spray is mainly focused on the description of the statistical mean diameter and the mass flux after the impingement. The main results highlight that the mean diameter value of the secondary droplets does not change during the Leidenfrost regime and increases for lower surface temperature. This behavior is strongly correlated to the liquid film formation for temperatures lower than the Leidenfrost point. The expelled mass flux exhibits a similar behavior but a decrease is observed after a given temperature, which can be attributed to the deepening of the liquid, leading to a reduction of the number of expelled droplets.
机译:为了调查液滴撞击到刚性壁上的动态行为,已经进行了大量的研究。他们中的大多数只处理单个液滴,只有很少的液滴用于喷雾,为此实施了多种诊断方法。此外,当涉及喷雾时,液体质量通量通常很低(大约几kg / m 2 / s),并且主要考虑表面寒冷的情况。因此,目前的实验工作旨在研究喷雾在液体质量通量高达13 kg / m〜2 / s时对热表面(高达800℃)的冲击。具体而言,主要目标是从莱顿弗罗斯特(Leidenfrost)领域开始,根据表面温度表征次要液滴。为此,二维相位多普勒分析仪(PDA)与红外摄像机同步,以便同时测量局部液滴尺寸和速度分布随表面温度的时间演变。为了获得宽范围的撞击条件(法向入射韦伯和液体质量流量),使用了六次全锥喷雾。当表面保持在室温下时,也进行冲击特性的比较。另一个重要点还涉及表面的存在对喷雾流的影响。结果清楚地表明,入射液滴的轨迹因固体壁本身的存在而改变,并且强烈依赖于温度表面。喷雾冲击特性的深入研究主要集中在统计平均直径和冲击后质量通量的描述上。主要结果表明,次级液滴的平均直径值在莱顿弗罗斯特状态下没有变化,而在较低的表面温度下会增加。对于低于莱顿弗罗斯特温度的温度,此行为与液膜形成密切相关。排出的质量通量表现出相似的行为,但是在给定温度后观察到下降,这可以归因于液体的加深,从而导致排出的液滴数量减少。

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  • 作者单位

    LEMTA, UMR 7563, Universite de Lorraine, Vandoeuvre-Les-Nancy 54518, France LEMTA, UMR 7563, CNRS, Vandoeuvre-Les-Nancy 54518, France;

    LEMTA, UMR 7563, Universite de Lorraine, Vandoeuvre-Les-Nancy 54518, France LEMTA, UMR 7563, CNRS, Vandoeuvre-Les-Nancy 54518, France;

    LEMTA, UMR 7563, Universite de Lorraine, Vandoeuvre-Les-Nancy 54518, France LEMTA, UMR 7563, CNRS, Vandoeuvre-Les-Nancy 54518, France;

  • 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

    Spray cooling; Phase Doppler measurements; Infrared thermography; Spray impingement;

    机译:喷雾冷却;相位多普勒测量;红外热像仪;喷雾撞击;
  • 入库时间 2022-08-18 00:18:16

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