【摘要】 利用Pro/e软件建模得到扭带模型,采用Fluent软件对换热管内的流场进行模拟,研究了扭率(Y)分别为12.0,8.5,5.0的扭带在管内的阻力特性和强化传热特性。实验结果表明,选择网格数为8.13×106的扭带模型较适宜。插入扭带管的管内压降大于光管的管内压降,随雷诺数(Re)的增大,管内压降增大,且Y越小管内压降越大。插入扭带后,随Y的减小,达西摩擦因子(λ)不断增大。Y越小,管内流体的二次流流速越大,温度场与速度场协同的程度更好,换热效果得到强化。所建立的拟合曲线λ=3.328Re-0.286Y-0.394和Nu=0.115 4Re0.707 7Pr0.333Y-0.078 75(Nu为努赛尔数,Pr为普朗特数)拟合度高,利用λ,Nu,Re,Y关联式可进行扭带选型。更多还原

【Abstract】 A twisted tape model was established by means of the Pro/e software and flow field in a heat exchange tube was simulated by means of the Fluent software. Pressure drop and heat transfer enhancement in the tube with the twisted tapes(twisting ratios(Y) of 5.0,8.5 and 12.0) for gas fluid were studied. The experimental results indicated that the optimum grid number was 8.13×106. The pressure drop in the tubes with t he twisted tapes was greater than that in the plain tube,and increased with the increase of Reynold number(Re) and the decrease of Y. The Darcy friction factor(λ) increased with the decrease of Y. Secondary flow appeared in the tube with the twisted tapes,so the synergy between temperature field and velocity field was improved and then heat transfer effect was enhanced. The established simulating curves,namely λ=3.328Re-0.286Y-0.394 a nd Nu=0.115 4Re0.707 7Pr0.333Y-0.078 75,had high fitting degree. An engineering method for selecting the twisted tapes was proposed through using the empirical relations between Nu,λ,Re and Y.更多还原