大型弓形截面螺旋管中流体流动与传热性能研究

Study on fluid flow and heat transfer performances in large arcuate cross-sectional helical pipes

以水为介质,通过数值模拟对湍流条件下截面圆心角α在90°~180°范围内、螺旋直径在1000~4500 mm之间的大型弓形截面螺旋管中流体流动与传热性能进行模拟研究。结果表明,在一定的体积流量下,截面圆心角小于180°的弓形截面管相比半圆形截面管具有更好的综合换热和经济性能。α为90°时的PEC可达180°时的1.18倍。当交换相同的热量时,α为90°的弓形截面管比半圆管所需材料可减少约71.6%。在大量数值模拟结果基础上,通过引入截面圆心角变量α,拟合得到了弓形截面螺旋管中流体流动与传热准数Nu和f关联式。数值验算表明,关联式精度较高,可用于大型弓形截面管夹套的工艺计算。

Using water as the medium,the fluid flow and heat transfer performance in large arcuate helical pipes with the central angles of 90°~180°of the cross-sections and the helical diameter of 1000~4500 mm were numerically studied under turbulent flow conditions.The results show that under a certain volume flow rate,the arcuate sectional pipe with the central angles of less than 180°of the section has better comprehensive heat transfer performance and economy than the half-round sectional pipe.Whenαis 90°,the PEC can reach 1.18 times that of 180°.If the same amount of heat is exchanged,the material consumption of the arcuate helical-pipe with a center angle of 90°can be reduced by about 71.6%compared with the half-round sectional pipe.Based on large quantity of numerical simulation results,correlation formulas of Nu and f for large arcuate helical pipes were obtained by introducing the central angleαof the cross-sections and by fitting.Numerical verifications show that the correlation formulas are accurate enough and can be used in engineering for process calculations of large arcuate helical-pipe jackets.