【作者】 岑仁海；

【导师】 朱蒙生；

【作者基本信息】 哈尔滨工业大学 ， 流体力学， 2009， 硕士

【摘要】 能源在社会经济的发展中起着举足轻重的作用,当今社会经济正处于高速发展阶段,对能源的需求更加迫切。由于在液体中加入少量的表面活性剂可导致其流动阻力大幅度地减少,即添加剂减阻现象,此时不但流体输送过程中的摩阻系数显著下降,而且会因传热性能降低而减少沿程输送的热量(或冷量)损耗。因此在我国开展此项技术的研究对节能减排的工作具有重要的意义。表面活性剂减阻流体具有良好的流动控制性能和机械稳定性,应用前景十分广泛。本文针对表面活性剂在高温中的实验,在实验台原有的基础上进行了设备的升级,以满足系统对温度的要求。清水实验结果表明,清水在层流区域很好地符合Hagen-Poiseuille定律,在湍流区域符合布拉休斯定律,从而为率定减阻管道直径和CTAC水溶液的减阻实验提供了有力的证据;建立了减阻实验结果所依据的三个基准:Hagen-Poiseuille定律,布拉休斯定律以及Zakin线;推导了减阻实验所需范宁摩擦阻力系数与雷诺数的关系式。其次根据在铜管和紫铜管不同温度,不同浓度和不同雷诺数下进行减阻实验,从而得出了CTAC的减阻效果:在相同温度和雷诺数下,减阻效果随着溶液浓度的增加而增强;在相同浓度和雷诺数下,温度愈高,摩阻系数愈小,减阻效果愈好;当在浓度为150ppm时,CTAC溶液的减阻效果随着溶液温度的升高而增强,但是当温度达到60℃时,减阻几乎消失了,对于高浓度的情形,在温度为60℃时仍然出现明显的减阻效果;在紫铜管中,当浓度为300ppm和400ppm,温度为50和60℃时,CTAC溶液的减阻百分比达到了0.6-0.8,但是当温度达到70℃时,减阻几乎消失了,结果表明了CTAC水溶液在温度上有个适用的范围,在70℃以上效果不好,即表面活性剂对减阻都有一个上限绝对温度;减阻效果表现在一定的雷诺数范围内,当Re超过一定值时,减阻效果大幅度下降。最后概述了目前存在的几种和湍流联系密切的添加剂减阻机理假说。通过分析了表面活性剂的微观特征及其减阻的化学机理,以表面活性剂的物理化学性质为基础,把粘弹性和湍流猝发相结合,探讨了添加剂的减阻机理,进一步完善了湍流猝发受抑制假说。本文的研究成果为减阻剂CTAC应用于工程实际,提供了有益的参考。更多还原

【Abstract】 Energy is always playing a very important part in our society. Today our economy is developing faster and faster and it relies on energy to supply the development power. Because the additive drag-reduction phenomenon, which can lead to great reduction of friction drag by adding a little surfactant into the fluid, could not only significantly reduce the friction coefficient during the fluid distribution process, but also decrease the heat loss (or cold loss) along the distribution network due to the reduction of the heat transfer. So it is of great significance for energy conservation to investigate additive drag-reduction. Based on its endurance to mechanical, chemical, actinic and thermal effect, the importance of the surfactant using in drag-reduction has been widely emphasized by engineers.Firstly, we improved a closed loop experimented system to meet the temperature requirements. The results indicates that the relationship between Fanning frictional factor and Reynolds number meets Hagen-Poiseuille law in laminar flow and meets Blasius law in turbulent flow so that it can accurately ensure the diameter of experimental tube and provide powerful documents for surfactant solution experiments. Then it is important to establish three principles for drag-reducing experimental results: Hagen-Poiseuille law, Blasius law and Zakin’s asymptote. It is necessary to draw the relationship between Fanning frictional factor and Reynolds number.Secondly, according to different temperatures, different concentrations and different Reynolds number, we did drag-reducing experiment for surfactant solution so as to conclude the drag-reducing effect. Drag-reducing effect improves with concentration of solution increased under the same temperature and Reynolds number. Drag-reducing effect improves with temperatuer of solution increased under the same concentration and Reynolds number. the drag-reducing effect of CTAC solution enhanced with the temperature increased at 150ppm,the reduction almost disppeared when the temperature reaches 60℃,but there shows significant drag reduction effect in the high concentration of cases at 60℃; the drag-reducing effect reaches 0.6-0.8 at 300ppm,400ppm and 50℃,60℃in the copper pipe,but the drag-reducing almost disappeared when the temperature reaches 70℃,the results show that CTAC solution have an effective temperature range, it has a bad effects in the high-temperature More than 70℃, drag-reducing surfactant has an upper absolute temperature; and it shows that it has a effective Reynolds number range,when Re exceeds a certain value, the drag-reducing effect decline quickly. Finally, this paper introduces some drag-reducing mechanism related in turbulence at present. Through the analysis of the drag-reducing characteristics and the micro-chemical mechanism of surfactants, based on the physical and chemical properties of surfactant, and have a combination with turbulent burst to analysis the fluid drag-reduction mechanism, and further improved the suppression of turbulent burst hypothesis.The paper provides an useful reference for applying CTAC to practical projects.更多还原