【作者】 马宗豪；

【导师】 卞永宁；

【作者基本信息】 大连理工大学 ， 流体力学， 2009， 硕士

【摘要】 随着科学技术的发展,非牛顿流体的相关研究已经取得了非常重要的进展,尤其在生物领域研究更为深入。添加了聚合物和表面活性剂的非牛顿流体在水处理、石油开采以及生物化工等方面有着极为广泛的应用。国内外很多学者对二维、三维流路中的非牛顿流体进行研究,但对易于产生流动分离、强化热质传递的正弦波壁管的研究还未见报道,本文主要研究了定常流场下非牛顿流体在波壁管内的流动特性,重点研究了它的减阻特性,关注了非牛顿流体与牛顿流体的转捩点的变化,并辅以适当的数值模拟和可视化结果予以说明,具体内容如下:第一章回顾了国内外的研究进展,总结了二维和三维流路内的非牛顿流体特性。现有研究结果表明,二维流路的研究比较早,也相对成熟,实验结果与数值结果比较吻合,三维圆管的研究早在50年代就被Toms发现:加入聚合物、添加剂能有效地降低流体的流动阻力,提高了管道间的传热效率,但是转悷点却明显延迟。目前对具有较高的质热传递速率的波壁管的研究却鲜见报道,这促使本研究进行相关探讨。第二章介绍了本研究所采用的实验设备和测试方法。测试段选取D_max/D_min=3.3和D_max/D_min=2两种波壁管路,采用旋转粘度计和玻璃管粘度计测量了包括剪切粘度、剪切应力、表观粘度等在内PAM的基本物性。用自行设计的自循环实验系统对PAM聚合物溶液在波壁管内的流动特性进行了研究,并用铝尘法完成了波壁管路内的流动可视化。第三章给出了实验结果并进行相关讨论。首先,分析了PAM聚合物溶液的流变特性曲线。其次,通过测试系统实验得到了PAM聚合物溶液在波壁管内的f-Re曲线,发现了PAM在波壁管内的减阻现象,通过不同浓度PAM溶液的比较,发现了其最佳的减阻浓度,并且过渡流对应的转捩点也发生了提前,同时利用可视化技术验证了转捩点提前的结论。运用FLUENT进行数值模拟,得到了流体的速度和压力分布,摩擦曲线与实验值很接近。第四章总结了本研究的成果,第五章指明了将来的研究方向。更多还原

【Abstract】 The investigation of Non-Newtonian fluid in the industry has improved greatly with the development of science and technique, especially in the field of biology. The additive polymers and surfactants have extensive use in disposing water, petroleum industry and biochemical plant aspect. Lots of researches focus on the flow characteristic of non-Newtonian fluid in 2-D and 3-D pipes, but relatively a little in a wavy-walled tube which is apt to bring the separation flow and enhance the mass and heat transfer. The paper mainly investigates the flow characteristic of non-Newtonian fluid in a wavy-walled tube, especially the drag reduction. At the same time, the proper numerical simulation and flow visualization are compared with experimental result. The details follow:In chapter 1, the studies that the flow characteristic of non-Newtonian fluid in pipes have been reviewed. It is shown the experimental results in channel are coincident with the numerical simulation. In 50’s, Toms found that dissolving a small amount of polymers in water can drastically reduce the pressure drop in the straight pipe and improve heat transfer, but the transitional point delays compared with water. The researches of non-Newtonian fluid in wavy-walled tube which enhances the mass and heat transfer haven’t been under way.In chapter 2, the experimental facility and measurement techniques used in the study are introduced. Two kinds of wavy-walled tubes are selected in test section. The basic physical characteristics such as shear viscosity and shear stress are educed by a revolving viscosimeter. The flow characteristic of non-Newtonian fluid in wavy-walled tube is studied by a circulating system and the flow patterns are visualized by the aluminum dust method.In chapter 3, the experimental results are discussed. First of all, rheology of PAM is analyzed. Next, the f-Re curve of PAM polymer solution in wavy-walled tube is attained and the drag reduction phenomenon is observed. The best drag reduction effect is received via various concentration PAM while the transitional flow moves up as the drag reduction compared with the Newtonian fluid. The velocity and pressure distributions of PAM are acquired by using FLUENT6.0 and ihef-Re curve is similar to experimental result.Chapter 4,5 indicates the possible extensions of the present work.更多还原