【作者】 车刘杰；

【导师】 张定才；

【作者基本信息】 中原工学院 ， 供热、供燃气、通风及空调工程， 2010， 硕士

【摘要】 内螺纹肋管是一种被广泛应用的强化传热管。本文通过数值模拟的方法,研究内螺纹肋管和中心被堵内螺纹肋管的流动与传热规律。肋参数范围:无量纲肋高H为0.02~0.06,肋数N为35~50条,螺旋角γ为35°~45°。分析肋高、肋数、螺旋角变化对努塞尔数Nu和阻力系数f的影响,并通过实验验证。对中心被堵内螺纹肋管进行数值模拟,中心堵管与外管内径比d/D的范围为0.2~0.5,分析中心堵管管径变化对流动与传热的影响。主要结论如下:1、随着螺旋角的增大,Nu和f均先增大后减小,在螺旋角为41°时,Nu达到最大,在螺旋角为39°时,f达到最大。内螺纹肋管Nu数与光管Nup数的比值Nu/Nu p=1.51～1.71,评价指标采用η=(j/jP)/(f/fP)1/3 ,η= 1.15～1.28。2、随肋数N的增加,Nu和f的变化都不大。Nu/Nu p的变化范围为Nu/Nup = 1.71～1.73,评价指标的范围在η= 1.279～1.281。3、随肋高的增加,Nu和f都有较大增加, Nu/Nu p随着肋高H(0.02~0.05)增加而单调递增, Nu/Nup的变化范围为1.59～1.83,评价指标的值为η= 1.24～1.30。4、通过对计算结果的分析,在所选择的肋几何参数范围内,最佳肋参数为0.50/40/41。5、对于中心被堵内螺纹肋管,当d/D在0.35~0.4之间变化时,Nu数增大的梯度很大,而f增大的梯度相对较小。6、对于中心被堵内螺纹肋管,η随着d/D的增大而增大,当d/D在0.2~0.5之间变化时,评价指标的值为1.57~2.05。更多还原

【Abstract】 As an effective configuration for heat transfer enhancement, the internally helical finned tube is widely employed. This paper provides heat transfer and friction characteristics of the internally helical finned tube in numerical and experimental investigation, the internally helical finned tubes were measured during fin geometry ranges of non-dimensional rib height(0.02 to 0.05), number of rib starts(35 to 50),helix angle(35 to 45deg).Analysing the impact of fin number,fin height and helix angle on the Nusselt number and the friction factor,then experiments verify the numerical results . Analysing the impact of non-dimensional radius(0.2~0.5) on the Nusselt number and the friction factor of the internally helical finned tube with center blocked in numerical investigation.The major findings are as follows:1. The Nusselt number and the friction factor increase first,then decrease with the increase in helix angle. whenγ=41°,Nu is peak, whenγ=41°,f is peak.The ratio of the internally helical finned tube Nu number to the plain tube Nup is written Nu/Nu p, Nu/Nu p=1.51~1.71,the values of evaluation indexη=(j/jP)/(f/fP)1/3isη1.15~1.28.2. The number of rib starts variation causes a little increase the Nusselt number and the friction factor. The values of Nu/Nu paugment with the increase in the number of rib starts (35~50), Nu/Nup = 1.71～1.73,andη=1.279～1.281.3. The fin height variation causes a dramatic increase of the Nusselt number and the friction factor.When the range of fin height is 0.02~0.05, Nu/Nu p=1.59～1.83,andη= 1.24～1.30.4. Analyzing the numerical results,0.50/40/41 is the best rib combination of all.5. With regard to the internally helical finned tube with center blocked ,when d/D=0.35～0.4, the grades of Nu increase greatly ,however, the grades of f increase smaller.6. With regard to the internally helical finned tube with center blocked ,ηaugment with the increase in d/D when d/D=0.2~0.5,the range ofηvalue isη=1.57～2.05.更多还原