低Reynolds数条件下水流纵掠长冰柱沿方位角传热特性

Heat transfer characteristics of water flowing along icicle at low Reynolds number

通过实验研究了低Reynolds数条件下水流纵掠长冰柱过程的沿方位角相界面移动规律及传热特性。改变水流速度、水流温度、冰柱尺寸及冰柱初始温度等控制参数,采用非接触测量方法获得了冰柱融化图像,基于影像实验数据与冰柱相界面传热系数之间的映射关系,分析了沿方位角对流传热系数等传热参数的变化规律。结果表明:各测量点的沿方位角Nusselt数不同,随着融化过程的进行,各测量点的沿方位角Nusselt数值均先增大后减小,整个融化过程中间某处存在最大值;其余实验控制参数不变的条件下,沿方位角对流传热系数均随着水流速度或水流温度的增大而增加;获得了水流纵掠冰柱融化过程Nu?与Gr、Re、Pr、Ste及?之间的关联式。

The heat characteristics and moving regulation of phase change interface during the progress of water flowing along icicle at low Reynolds number are investigated. The mapping relationship between the experimental data and the heat transfer coefficient in phase change interface of icicle is built. Moving regulation of phase change interface of icicle is recorded by using industrial cameras through changing initial dimension of icicle, initial temperature in icicle, velocity and temperature of water. By analyzing the experimental results, some conclusions are as follow： the number of azimuths is different for each measurement point, as the melting process is carried out, the Nusselt number values of the measurement points increase first and then decrease, and there is a maximum value in the middle of the whole melting process. The convective heat transfer coefficient along the azimuth angle increases with the increase of the velocity or temperature of the water flow under the condition that the remaining experimental control parameters are unchanged. Empirical correlation of Nuф,Gr, Re, Pr, Ste and ф is obtained.