热通量对流传输方程框架下的涡流管中能量分离原理研究

The vortex tube is a device which can separate hot and cold air streams from compressed air simultaneously. It is widely applied in such fields as heating, cooling, and separating of gas mixtures because of its various advantages. In spite of the simple geometry of the vortex tube, its real physical processes and the energy separation nature are far from being fully understood, and there is no theory can explain consistently the energy separating mechanism in the vortex tube. Because the theoretical value of the coherent energy separation in the vortex tube is very large, as well as the vortex tube has great potential applications, it is definitely worth to further investigate the mechanism of energy separation in the vortex tube. In view of the above mentioned facts, this project tries to cast the heat transfer processes occur in the vortex tube into a frame of the convective transport equation of the heat flux, to separate the contributions to the transport of the heat flux enforced by the different movements of the small fluid element. It is expected to find out the mechanism of the energy separation in the vortex tube from the process information provided by the convective transport equation of the heat flux. To realize the above mentioned intention the theoretical, experimental and numerical methods are used to analyze the mechanism of the energy separating in the vortex tube from the aspects followed. (1) The convective transport equation of the heat flux that is suitable to the vortex tube will be found. (2) The experimental method is used to find out the effect of the wall curvature on the turbulence wall law of the concave wall, based on such effect a modified turbulence k-ε model should be established, furthermore, the heat transfer field distribution characteristics and the vorticity field distribution characteristics will be obtained using a numerical method based on modified turbulence k- ε model. (3) The separating process of the contributions the different movements of the small fluid element to the transport of the heat flux is performed. (4) The contribution of vorticity to the transport of the heat flux will be summarized and the main factors influencing the energy separation will be analyzed, based on results formed in this process, the mechanism of the energy separation in the vortex tube can be summarized. The results of this project will reveal in-depth the energy separation mechanism in the vortex tube, and also provide theoretical support for promoting the energy separation efficiency in the vortex tube. Furthermore, the results obtained can be used in the other cases that use vorticity to enhance heat or mass transfer.

涡流管是一种能够将压缩空气同时分离出冷热气流的装置，被广泛应用于制冷、制热、混合物分离等领域。发生在管内的能量分离机理极其复杂，至今没有一种理论能够从本质上解释该现象。究其原因是现有解释基于对流传热能量方程，该方程只描述了传热的结果，所提供的传热过程信息较少。近来发展的热通量对流传输方程能提供较丰富的传热过程信息。为此，项目拟在热通量对流传输方程框架下研究涡流管中能量分离机理。项目拟开展4方面的研究：(1) 推导涡流管热通量对流传输方程；(2) 用实验得到壁面曲率对湍流壁面律的影响，进而获得考虑壁面曲率影响的修正k-ε模型；（3）分离涡流管中流体微元运动形式对热通量各分量传输的贡献；(4) 归纳涡流管中涡量对传热贡献规律，形成涡流管内能量分离机理。研究结果不但可揭示对流传热现象内在机理，还能为提高涡流管能量分离效率提供理论依据，同时，还能为其它用涡量实现强化传热传质装置的设计提供理论依据。

涡流管是一种能够将压缩空气同时分离出冷热气流的装置，被广泛应用于制冷、制热、混合物分离等领域。发生在管内的能量分离机理极其复杂，出现热量从低温向高温传输的现象，表面上与热力学第二定律相悖，但因在涡流管内高品位能量的消耗，实际上熵是增加的，从而并不违背热力学第二定律。遗憾的是至今没有一种理论能够从本质上解释该现象。项目在热通量对流传输方程框架下研究涡流管中能量分离机理。项目推导涡流管热通量对流传输方程；用方程严格的描述了涡量对热通量对流传输的贡献：在涡流管内，热通量总是沿着指向中心的半径方向，而涡量的贡献就是推动热通量沿径向传输；通过分离涡流管中流体微元运动形式对热通量各分量传输的贡献，归纳出了涡流管中涡量对传热贡献规律，形成涡流管内能量分离机理：能量分离过程需要两个基本过程,其一是在管子中心气体的膨胀过程，气体要能释放出内能使其温度降低，形成沿指向圆心半径方向的热通量，向其二是气体要有较大的涡量，在涡量对热通量对流传输贡献的作用下，对流把热通量沿半径方向传输。形成了涡量管内的能量分离。. 由于项目涉及很有争议的物理现象，有较强创意及新意的研究结果不太容易得到审稿人的认同，发表比较艰难。目前还有一技术问题没有确认（正在进行中）。该技术问题是气体在涡流管内膨胀所做的机械功是如何传输的？. 项目基本上完成了预设的研究目标，项目部分究成果正在整理发表中，已在国内外发表标注期刊论文和会议论文 22 篇，已 被 SCI 收录 5 篇，EI 收录 3 篇；获得国外发明专利 6 项；出版英文专著一部。获甘肃省科学技术进步一等奖一项。培养硕士研究5名，博士研究生3名。. 该项目的研究结果意义较大，不光是增加对对流传热的理解，其结果也可为其它领域做出借鉴。因为在天体物理中有非常类似涡流管内物理现象的现象。吸积盘中有热量从低温传向高温的现象，目前的理论能证明这一过程是熵增的，但还不能解释这一看似反常的物理现象是如何形成的。