单排不均匀排管流动换热特性的实验研究

An Experimental Investigation on the Performances of Airflow across Tubes with Uneven Pitches

对空气横掠不均匀排列的单排管的流动与换热特性进行了实验研究．实验在小型风洞中进行．流动阻力采用总体静压降法获得而换热系数采用单管热平衡法得到．改变管排的管间距获得在不同间距下的流动与换热的准则关系式．分析结果表明，在不同间距下流动阻力和换热能力变化较大，随着管间距不均匀性的增加，会出现换热系数最大值和流动阻力系数最小值，但这种现象随着雷诺数的加大而逐渐消失．

The flow and heat transfer characteristics of the airflow across a row of tubes arranged unevenly are investigated. The experimental measurement was made in a small size wind tunnel. The heat transfer coefficients were determined with a thermal balance of single tube heated and the flow drag coefficients were obtained by measuring the total static pressure difference. By changing the pitch between tube centers, the criterion relations of heat transfer and flow drag were obtained individually for different pitches. The results show that the performances of the flow and heat transfer vary obviously with the nonuniformity of pitches, and the maximum heat transfer and the minimum flow drag can be found under certain tube pitches, but the optimal situation disappears gradually with the increase of Reynolds number.