含扭曲片乙烯裂解炉管内流场的数值模拟

 基于网格生成法，采用计算流体力学对含扭曲片的乙烯裂解炉管内强化传热的流场(流速、压降和阻力损失)进行了数值模拟，并分析了扭曲片扭曲比对流场的影响。结果表明流体流经扭曲片，切向速度迅速增大；流出构件后，切向流速沿轴向逐渐变小，而沿径向逐渐增大。在管径方向存在一个轴向速度等于整个截面平均轴向速度的点。管内总压降及扭曲片局部压降均随雷诺数增大而增大，不随管径变化而变化。管内平均阻力系数与雷诺数呈线性关系，随雷诺数增大而变小；扭曲片局部阻力损失随雷诺数的增大而迅速增大，随管径减小而增加。扭曲比对管内流场有影响，较佳的取值范围为2.4~2.6。

NUMERICAL SIMULATION OF FLOW FIELD IN TUBE OF ETHYLENE CRACKING FURNACE WITH TWISTED SLICE

Based on the gridding partition and computational fluid dynamics,the flow field(velocity,pressure drop and resistance loss) of heat transfer enhancement in tube of ethylene cracking furnace with twisted slice was simulated.The effect of twist ratio on the flow field was analyzed.The results showed that tangential velocity increased rapidly while fluid flowed through the twisted slice,and then decreased gradually along the tube axis and augmented gradually along the tube diameter while fluid flowed out from the twisted slice.In the direction of the tube diameter,there existed a point where axial velocity was equal to the average axial velocity of the whole tube section.The whole pressure drop in the tube and local pressure drop in twisted slice both rose with the increase of Reynolds number(Re),which were independent of the tube diameter.Average resistance coefficient in the tube had a linear relationship with Re,which reduced with the increase of Re.Local resistance loss in twisted slice enhanced with the increase of Re and the decrease of the tube diameter.Twist ratio had an influence on the flow field in the tube,whose optimal numeric range was 2.4-2.6.