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采用数值计算和流动显示方法,对矩形封闭空间内水平放置三根电缆所引起的自然对流,在Gr~*=9.2×10~4—6.5×10~6范围内进行了理论和实验研究。结果表明,这种情形下的自然对流流动存在着环流。在低Gr~*数时,在电缆上方形成主环流;随着Gr~*数的增大,在电缆间出现涡流;在Gr~*=6.5×10~6时,电缆间出现成对的涡流。实验结果表明,硬脂酸锌粉粒是显示空气自然对流流动的比较理想材料。采用伪非稳态变系数方法是保证计算收敛而又节省机耐的有效方法。计算结果为设计该类型电缆的最大允许载流量提供了依据。
The natural convection caused by the horizontal placement of three cables in a rectangular confined space was studied by numerical calculation and flow display method. Theoretical and experimental studies were carried out in the range of Gr ~ * = 9.2 × 10 ~ 4-6.5 × 10 ~ 6. The results show that the circulation of natural convection in this situation exists. When Gr ~ * = 6.5 × 10 ~ 6, there is a pair of eddy currents between the cables . The experimental results show that zinc stearate powder is an ideal material to show the natural convection of air. The use of pseudo-non-steady-state variable coefficient method is to ensure that the calculation of convergence and save machine resistance is an effective method. The calculation results provide the basis for designing the maximum allowable current carrying capacity of this type of cable.