Jet Impingement Boiling From a Circular Free-Surface Jet During Quenching: Part 1—Single-Phase Jet
Jet Impingement Boiling From a Circular Free-Surface Jet During Quenching: Part 1—Single-Phase Jet
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淬火过程中圆形自由表面射流的射流冲击沸腾：第 1 部分 - 单相射流
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
R. Viskanta
中科院分区：
文献类型：
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作者：
D. Hall;F. Incropera;R. Viskanta
一种用于控制射流冲击沸腾传热的建议技术涉及将气体喷射到液体射流中。本文报道了沸腾传热的实验研究结果，在淬火过程中的圆柱形铜试样，最初在一个均匀的温度超过对应于最大热通量的温度，由两相（水-空气），圆形自由表面射流。第二相作为小气泡被引入喷嘴出口上游的射流中。单相对流传热的停滞点，以及在沸腾曲线的形式，最大热通量，和最低膜沸腾温度的位置从停滞点延伸到一个半径为10喷嘴直径的数据。对于空隙率范围为0.0至0.4，纯液体速度范围为2.0至4.0 m/s（11，300 ≤Re d，fo ≤ 22，600）的情况，将气泡引入射流会产生几个显著的影响。以及提高单相对流传热的系数为2.1的停滞区，除了增加的气泡的壁沸腾，并消除了与停止沸腾相关的温度漂移。最大热通量不受空隙率变化的影响，而最低膜沸腾温度随着空隙率的增加而增加，膜沸腾传热量随着空隙率的增加而减小。一篇配套论文（Hall等人，2001）详细描述了单相射流的相应结果。
A proposed technique for controlling jet impingement boiling heat transfer involves injection of gas into the liquid jet. This paper reports results from an experimental study of boiling heat transfer during quenching of a cylindrical copper specimen, initially at a uniform temperature exceeding the temperature corresponding to maximum heat flux, by a two-phase (water-air), circular free-surface jet. The second phase is introduced as small bubbles into the jet upstream of the nozzle exit. Data are presented for single-phase convective heat transfer at the stagnation point, as well as in the form of boiling curves, maximum heat fluxes, and minimum film boiling temperatures at locations extending from the stagnation point to a radius of ten nozzle diameters. For void fractions ranging from 0.0 to 0.4 and liquid-only velocities between 2.0 and 4.0 m/s (11,300≤Re d,fo ≤22,600), several significant effects are associated with introduction of the gas bubbles into the jet. As well as enhancing single-phase convective heat transfer by up to a factor of 2.1 in the stagnation region, addition of the bubbles increases the wall superheat in nucleate boiling and eliminates the temperature excursion associated with cessation of boiling. The maximum heat flux is unaffected by changes in the void fraction, while minimum film boiling temperatures increase and film boiling heat transfer decreases with increasing void fraction. A companion paper (Hall et al., 2001) details corresponding results from the single-phase jet.