管内周期性自旋流的强化传热实验

Experimental investigation on heat transfer enhancement of periodic free swirl in tube

对间隔插入旋流片管内周期性自旋流的传热与流阻性能进行了实验研究,并比较了4种类型的旋流片及其不同旋流片间距的强化传热性能。结果表明,最佳旋流片间距Lp均在33d左右,旋流片强化传热的综合效果从大到小依次为:旋转角α=180°及旋流角β=20.3°的旋流片、旋转角α=270°及旋流角β=20.3°的旋流片、旋转角α=180°及旋流角β=38.1°的旋流片、旋转角α=270°及旋流角β=38.1°的旋流片。

The characteristics of heat transfer and flow resistance of free swirl flow caused by twisted-leafs discontinuously in circular tube are experimented, and the heat transfer enhancement of four types twisted-leafs in different twisted-leaf pitch Lp is analyzed. The results indicate that the optimum twisted-leaf pitch Lp is around 33d（d means the width of twisted-leaf）and the sequence of twisted-leafs is 180°-20.3°（it denotes a type of twisted-leaf with twist angle α=180° and swirl angle β=20.3°） , 270°-20.3°, 180°-38.1°and 270°-38. 1° according to the valuation factor from high to low.