带斜截半椭圆柱面空冷器的传热和流阻特性数值模拟

Numerical simulations on characteristics of heat transfer and flow resistance in air cooler with oblique-cut semi-elliptic cylinder shell

在Re=400~2200范围内,对管后分别布置一对斜截半椭圆柱面和三角形小翼涡流发生器的顺排和叉排翅片圆管空冷器气侧传热和流阻性能进行数值模拟。结果表明两涡流发生器强化传热效果相当。由于流线型设计,斜截半椭圆柱面在顺排管和叉排管空冷器中产生的流阻分别比三角形小翼低0.07%~2.53%和1.51%~5.31%,在叉排管空冷器中,两涡流发生器在较高Re下均具有流动减阻效果,斜截半椭圆柱面最多可减阻6.40%,三角形小翼最多可减阻4.39%。顺排管空冷器中斜截半椭圆柱面综合性能R=（j/j0）/（f/f0）值在Re〉700时比三角形小翼高0.68%~4.36%,叉排管空冷器中斜截半椭圆柱面综合性能R值比三角形小翼高0.79%~4.78%;斜截半椭圆柱面在叉排管空冷器中的综合性能R值比其在顺排管空冷器中高3.11%~28.38%。

The characteristics of heat transfer and flow resistance on the air side in a finned circular-tube air-cooler with a pair of oblique-cut semi-elliptic cylinder shells or delta winglets behind circular-tubes were investigated numerically.In-line and staggered arrangements of two rows of circular-tubes in the air cooler were considered,separately.The Reynolds number of the air flow ranged from 400 to 2200.The heat transfer enhancement and flow resistance of these two vortex generators were compared by using the comprehensive performance factor R=（j/j0）/（f/f0）.The results show that the two vortex generators have almost the same heat transfer enhancement performance.However,due to the streamlined design of oblique-cut semi-elliptic cylinder shells,the corresponding flow resistances in the air coolers with in-line and staggered tubes are 0.07%—2.53% and 1.51%—5.31% lower than those of delta winglets,respectively.The two vortex generators have better effect on flow resistance reduction in the air cooler with staggered tubes at higher Reynolds numbers.The reduction of oblique-cut semi-elliptic cylinder shells is 6.40% at most and that of delta winglets is 4.39%.The R value of oblique-cut semi-elliptic cylinder shells is 0.68%—4.36% higher than that of delta winglets in the air cooler with in-line tubes for Re700,and it is 0.79%—4.78% higher in the air cooler with staggered tubes.Moreover,the R value of oblique-cut semi-elliptic cylinder shells in the air cooler with staggered tubes is 3.11%—28.38% higher than that with in-line tubes.