摘要
采用有限体积法,对双尺度串列圆柱的绕流换热进行二维瞬态数值模拟.主圆柱直径D固定,小圆柱直径d从0.2D变化至D.基于主圆柱直径D的ReD数为100和200.在间距比L/D=2,3,3.5,4,5,7下进行模拟.小圆柱分别放置在主圆柱的前面和后面.在经过与其他文献细致的比较验证后,研究表明:对于双尺度串列圆柱布置,流动型态转变的临界间距比在2和4之间.上游圆柱的存在使得下游圆柱的平均阻力系数有很大的降低,但其本身的平均阻力系数受到下游圆柱的影响较小;小圆柱后置较前置情况,对换热更为有利;而且,当两圆柱的间距大于4后,系统总换热量随间距的改变变化很小,且此时d/D=0.8和d/D=1两种情况下总换热量增长率很接近,这意味着在列管式换热器中,有可能采用大小直径的圆柱组合,一方面体积换热变化很小,另一方面却可达到节约管材耗量的效果.
Unsteady laminar flows passing two in-line isothermal circular cylinders were simulated using the finite element method. The diameter of the large cylinder D was fixed,while that of the smaller cylinder d varied from0. 2D to D. The Reynolds numbers based on diameter D were set at 100 and 200. The analysis was carried out for center-to-center spacing ratios,L / D,of 2,3,3. 5,4,5,and 7. The smaller cylinder was placed in front of or behind the large cylinder,with the numerical results validated by literatures. The research shows that,for the in- line dual- scale cylinders,the flow pattern changes when the critical spacing is between 2 and 4. The mean drag coefficients of the downstream cylinders is reduced greatly because of the upstream cylinders. But the mean drag coefficients of the upstream cylinders are affected slightly. The heat transfer density is better when the smaller cylinder is placed behind the larger one. Moreover,when the spacing ratio is greater than 4,the system total heat transfer density varies only slightly with changing spacing,and the total heat transfer rate is very close when d / D = 0. 8 and d / D = 1. 0,which means it is possible to conserve material consumption for the tube heat exchanger by using cylinders of different sizes while the variation of heat transfer density is slight.
出处
《江苏科技大学学报（自然科学版）》
CAS
2014年第6期563-569,共7页
Journal of Jiangsu University of Science and Technology:Natural Science Edition
基金
江苏科技大学启动基金资助项目(3501101)
关键词
多尺度结构
圆柱绕流
对流换热
dual-scale cylinders
flow past a cylinder
convection heat transfer
