﻿ 波浪管内二次流动数值分析
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 应用科技  2020, Vol. 47 Issue (3): 1-5  DOI: 10.11991/yykj.201910001 0

### 引用本文

CAI Baowei, HAN Fanglin. A numerical study on the secondary flow in a wavy tube[J]. Applied Science and Technology, 2020, 47(3): 1-5. DOI: 10.11991/yykj.201910001.

### 文章历史

A numerical study on the secondary flow in a wavy tube
CAI Baowei, HAN Fanglin
Marine Design and Research Institute of China, Shanghai 200011, China
Abstract: In order to explore the flow field distribution in the wavy tube more credible to carry out the mechanization of its heat transfer enhancement, wavy tube exchangers are numerically simulated by the turbulence model and wall treatment method verified by experiments. By calculating the flow field inside the wavy tube under different working conditions, the formation mechanism, development of the secondary flow in the wavy tube and its influence on the heat transfer and resistance of wavy tube exchangers are illuminated. It indicates that, there is no strictly laminar flow in wavy tube, the secondary flow appears even in extremely low Re. The secondary flow produces two kinds of vortexes, which make different contributions to heat transfer and flow resistance, and the size and distribution of these two kinds of vortexes change with the elevation of turbulence, resulting in change of heat transfer enhancement and relative resistance of the wavy tube correspondingly.
Keywords: heat transfer enhancement    wavy tube    secondary flow    numerical simulation    heat transfer character    flow resistance character    comprehensive exchanging character    structure vortex    turbulence vortex

1 模型建立与网格划分

2 模拟结果分析 2.1 波浪管内二次流的形成和变化趋势

2.2 二次流对波浪管阻力特性的影响

Re<1 000时，采用层流模型进行计算；当Re>3 000时，采用RNGk-ε湍流模型进行计算，得到波浪管阻力系数随Re的分布如图7所示。

2.3 二次流对波浪管换热特性的影响

 $R = \frac{{N{u_{\rm{B}}}/N{u_{\rm{S}}}}}{{{{({f_{\rm{B}}}/{f_{\rm{S}}})}^{1/3}}}}$

3 结论

1)波浪管内不存在严格意义上的层流，即使在极低雷诺数工况下，垂直流动方向的截面上也会产生二次流。且形成的二次流可分为2种，一种是由波浪管的特殊结构形成的结构涡，另一种是在湍流化程度升高后形成的流动涡。

2)流动涡的形成伴随着阻力系数变化趋势发生改变，标志着惯性力的作用超过粘性力，波浪管内流体发生转捩并向更高湍流化程度发展。

3)结构涡对波浪管综合换热性能的贡献明显大于流动涡。因而随着流动涡的形成和发展，波浪管的综合换热能力相比直管的提升幅度逐渐降低。

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