【作者】 陈瑶；

【导师】 赵汉中；

【作者基本信息】 华中科技大学 ， 流体力学， 2006， 硕士

【摘要】 随着微机电系统(MEMS)和生物工程技术的发展,微尺度流动和传热问题受到越来越多的关注。微尺度管道流动的研究对微机电系统(MEMS)、生物芯片等的应用有重要意义。本文基于速度向前交错网格及带有压力修正格式的有限体积法,计算了滑移流动情况下,微尺度矩形管道中气体三维流动问题,讨论了管道中气体流动的速度、压力、质量流量、Darcy摩擦因子等动力学量,并与无滑移流动情况进行了对比。前人研究表明,当流动处于滑移区域( 10 ?3≤Kn≤0.1)时,N-S方程仍然适用,但需要考虑气体的稀薄效应,即采用速度滑移和温度跳跃的边界条件。本文以氮气作为研究对象。数值结果表明,当Kn = 0.055时,即处于滑移流动情况下,管道内气体的流动速度大于相同条件下无滑移流动的速度,且管道壁面上流动速度不再为零;管道内压力降较无滑移流动情况下的压力降平缓,这是由于压力降是用来克服壁面摩擦的,而滑移的边界条件导致较小的壁面摩擦;进一步研究发现,稀薄气体效应对微尺度矩形管道内气体流动的质量流量和Darcy摩擦因子会产生影响,随着稀薄效应的增强,质量流量增加而Darcy摩擦因子减小。本文得到的三维微尺度矩形管道内气体流动的计算结果同二维计算结果以及实验结果保持了相当的一致,但同时也显示出了三维效应,为真实的微尺度管道中气体三维流动的研究提供了一些参考。更多还原

【Abstract】 With the development of MEMS and biological engineering technology, more and more attention has been paid to the problems of micro-scale flow and thermal transmission. The study of flow in micro-scale tubes has great importance to the application of MEMS and biological chips.To describe 3-D gaseous slip flow in rectangular microtubes, finite volume method with pressure correction scheme and velocity ahead uniform staggered grid is adopted. The dynamic parameters, including velocity、pressure、mass flow rate、Darcy friction factor, have been analyzed and compared with non-slip flow. Many results in the literatures have suggested that in the slip regime( 10 ?3≤Kn≤0.1), N-S equation with slip velocity and temperature jump boundary condition can be applied. Nitrogen flows have been studied in this paper. Numerical results indicate that, for the case of slip flow and Kn = 0.055,the velocity of slip flow in the microtubes is bigger than that of non-slip flow,and the velocity on the wall is no longer equal to zero; the pressure gradient of slip flow is smaller than that of non-slip flow,that is, the pressure gradient overcomes the friction on the wall and the slip boundary condition results in smaller friction. Moreover, the influence of rarefaction effect on mass flow rate and Darcy friction factor are also investigated. We find that rarefaction effect increases mass flow rate and decreases Darcy friction factor.Our results of the 3-D gaseous slip flow in rectangular microtubes are consistent with 2-D numerical and experimental results. Besides,it also shows 3-D effect and gives some suggestion the study of 3-D gaseous flow in microtubes.更多还原