椭圆水管冷却壁对流换热与阻力特性研究

Study on convective heat transfer and flow resistance of cooling stave with elliptic water pipes

采用数值模拟的方法对冷却壁内等周长的椭圆水管管内换热和阻力特性进行研究,通过对椭圆水管内冷却水的进出口压力、速度和温度变化以及单位时间带走热量的讨论,引入综合换热效率,得出椭圆水管管内阻力系数和综合换热效率随短长轴之比的变化规律。计算结果表明：水管越圆,达到相同进口速度需要的压力差越小,冷却水进口速度相同时出口速度缓慢增大,冷却水管的阻力系数不断减小;同时,相同进口速度条件下冷却水的进出口温差越小,冷却水单位时间带走热量增加但幅度很小,椭圆水管内冷却水综合换热效率逐渐提高。从阻力损失和综合换热效率考虑,冷却壁采用等周长的椭圆水管时,短长轴之比在0.4~0.7较合适,且应适当增大进口速度来提高综合换热效率。

The numerical simulation method was used to study convective heat transfer and flow resistance properties of cooling staves with equal- perimeter elliptic water pipes. The pressure,velocity and temperature difference of cooling water between the inlet and outlet of cooling stave as well as the heat brought by cooling water in a unit time were discussed,and a parameter of comprehensive heat transfer efficiency was introduced. The influence rules of flow resistance and comprehensive heat transfer efficiency of water pipes with deferent b / a（ a and b stand for the lengths of long axis and short axis respectively） were obtained. The results shows that when the water pipes become rounder,smaller pressure of cooling water is needed to achieve the same velocity; the outlet velocity of cooling water increases slowly when the inlet velocity is stable; the flow resistance of cooling water pipes decreases gradually. At the same time,the heat brought by cooling water in a unit time increases slightly; the comprehensive heat transfer efficiency of cooling water increases gradually. Considering flow resistance and comprehensive efficiency of heat transfer,the appropriate b / a with the elliptic pipes is 0. 4 ~ 0. 7,and the water velocity should be increased appropriately to improve the comprehensive heat transfer efficiency.