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