理工科 论文摘要 英文翻译

Abstract
The pipe refers to the pipe fittings used for carrying all kinds of fluid in the pipe line. The common pipe fittings are the cast iron pipe, the steel pipe, the nonferrous metal tube, the non-metallic pipe ,the plastic pipe, etc. Pipes usually are circular and also they may be special-shaped pipes of non-circular cross-sections. It’s a kind of heat and quality transfer tool. And it used very extensively from the delivery pipe in daily life to the industrial pipeline and so on. We often meet with ordinary cross section pipe, and its simple structure and high performance features make it a wide range of applicability. Considering the heat transfer and the structure, the helical pipe has been used in many areas.
The helical pipe is widely applied in the efficient steam generator and cooler, nuclear reactor,utility boiler, petrochemical industry, aviation and aerospace industry, cooling of microelectronic device, food and pharmaceutical, refrigeration and cryogenic technology due to its high heat transfer efficiency and compact structure and easy processing and manufacture. And the heat transfer efficiency of the helical pipe compared with the straight pipe is much higher, which is mainly because of the second
flow on the cross section perpendicular to the helical line when the fluid flows in the helical pipe.
The second flow improves the heat transfer capabilities of the fluid by destroying the boundary layer of the fluid heat transfer, meanwhile increases the resistance of the flow. So it’s of significance to study the flow characteristic of the helical pipe in engineering practice.
At present the research question is mainly based on the experimental analysis and numerical simulation. In the recent years, numerical simulation method is also widely applied. This thesis carry out three-dimensional numerical simulation to flow and the heat transfer of the bending Semi-circular cross-section helical pipe by FLUENT software, and get micro information about temperature distribution and speed distribution of the fluid of the Semi-circular cross-section helical pipe. And according to the result of simulation, it reveals mechanism of the heat transfer of the fluid in the bending Semi-circular cross-section helical pipe and analyzes the performance of the flow and heat transfer of the Semi-circular cross-section helical pipe.
The main research contents and conclusions are as follows:
1 This article draws the physical model of the full development period fluid of Semi-circular cross-section helical pipe with the Gambit software,and also meshes and sets the boundary conditions with Gambit. Then take the 3-d simulation and calculation to the fluid flow and the heat transfer of the Semi-circular cross-section helical pipe with the Fluent software.
2It obtained the micro information about temperature distribution and speed distribution of the fluid of the Semi-circular cross-section helical pipe by numerical simulation analysis with the Fluent software.It studies the speed distribution and pressure distribution and temperature distribution from the entrance of section of 1.5 times.And the research shows that the secondary flow would strengthen the fluid heat transfer when the fluid fully developed in the bending Semi-circular cross-section helical pipe. Owing to the certain deviation in the result of the experiment, and the offset existed after coordinate transformation, the result of the speed distribution of secondary flow is unsatisfactory. But for the helical pipe whose outside is straight, it still can be seen that the secondary flow on the section under the small Re number is the
two vortex structure and it becomes the four vortex structure following the increase of the Re number.
3.From study different Reynolds number’s influence to the resistance of bending semi-circular cross-section spiral pipe and it’s heat transfer, it shows that the resistance of the flow increases with the increase of the Reynolds number;and the heat transfer Nu increases with the Reynolds number too ,which means the heat transfer is enhanced.
4.Study different pipe diameter ‘s influence to the resistance of bending semi-circular cross-section spiral pipe and it’s heat transfer,it shows that the resistance of the flow increases with the increase of the pipe diameter;and the heat transfer Nu increases with the pipe diameter too ,which means the heat transfer is enhanced.
Key words:helical pipe;secondary flow; numerical; simulation; Reynolds number;flow;heat transfer
摘要
管子泛指用于管道中输送各种流体的管件。

常见的有铸铁管、钢管、有色金属管、非金属管、塑料管等。

一般管子通常为圆形，也有制成非圆形截面的异形管。

它是我们非常常见的一种传热传质的工具。

从日常生活中的输水管到具有严格使用条件的工业用管道等等，用途非常广泛。

我们经常遇到的是普通圆形截面管，它的结构简单，性能优良等特性使它具有广泛的应用性。

但是在考虑到传热，结构等一些场合时，螺旋管道的应用就非常多。

螺旋管因其具有传热效率高、结构紧凑和加工制作方便等优点,在高效蒸汽发生器和冷却器、核反应堆、电站锅炉、石油化工、航天航空、微电子器件冷却、食品制药、以及制冷与低温技术等领域得到了非常广泛的应用。

螺旋管道的传热效率相对于直管道的高很多，主要是因为流体在螺旋管道内流动时，与螺旋线垂直的横截面上存在二次流动。

二次流破坏流体换热边界层提高了流体换热，但同时也会使流动阻力增加，研究螺旋管道内的流体流动特性在工程实际中具有重要意义。

目前所研究的问题主要是基于实验分析和数字模拟。

近几年来，数值模拟方法也应用的越来越广泛。

本文利用FLUENT软件对内弯半圆形截面螺旋管流体流动及换热进行了三维数值模拟，得到了内弯半圆形截面螺旋管流体温度场，速度场等微观信息。

根据模拟的结果，揭示了内弯半圆形截面螺旋管流体换热的机理，分析了内弯半圆形截面螺旋管流体流动及换热的性能。

主要研究内容和结论如下：
(1)本文用Gambit软件画出了内弯半圆形截面螺旋管充分发展段流体流动的截
面物理模型，并利用Gambit进行划分网格和设置边界条件，然后利用Fluent 软件对内弯半圆形截面螺旋管流体流动及换热进行三维数值模拟计算。

(2)通过Fluent软件进行数值模拟分析得到了内弯半圆形截面螺旋管流体的温
度场、速度场等细观信息。

并研究在距入口1.5倍的螺距的截面的速度场、压力场、温度场的分布情况。

研究表明：当流体在内弯半圆形截面螺旋管内充分发展后，流体产生二次流动现象，强化流体传热。

由于实验中的测量结果本身存在一定的偏差，经过坐标变换后得到的速度也存在一定的偏差，因
此二次流速度场并不十分理想。

但仍可以看出对于外壁为直边的螺旋通道，小 Re 数下横截面上的二次流为两涡结构，随着 Re 数的增大，二次流由两涡结构变为四涡结构。

(3)研究不同雷诺数对于内弯半圆形截面螺旋管的阻力及换热效果的影响。

研
究表明：流动阻力随着雷诺数的增加而增大；换热Nu随着雷诺数的增大而增加,即换热效果增强。

(4)研究不同管径对于内弯半圆形截面螺旋管的阻力及换热效果的影响。

研究表
明：流动阻力随着管径的增加而增大；换热Nu随着管径的增大而增加,即换热效果增强。

关键词：螺旋管；二次流；数值模拟；雷诺数；流动；换热。