Study on the control of longitudinal dispersion in oscillatory flows in pipes and on the presentation method of its phenomena

两个不同温度的流体储罐之间的纵向换热通过连接储罐的毛细管内的流体脉动得到极大的强化。通过对单根圆管的分析可知，换热与纵向温度梯度与脉动流体排量的平方成正比。在实际应用中，管束被用来获得足够的热量。在圆形管束中，每三根管子之间存在间隙，使换热性能变差。为了避免这一缺点，考虑了三角形、正方形和六角形截面以及圆形截面的管道。虽然三角形管与单管相比具有最好的换热特性，但在相同截面…条件下，管壁厚度及其导热系数是决定管束性能的重要参数更多的面积、壁厚和流体脉动幅度。通过改变波壁的波数、波幅以及流体的脉动频率和波幅，研究了波壁的影响。壁面波纹度越大，换热越强。在控制流体脉动幅值和频率的换热动态响应方面，波纹管优于光滑管，并对该装置的换热机理进行了深入研究。我们发现了一个热传递到更高温度端的区域，这个区域发生在流体和温度脉动之间的相位滞后超过π/2的区域。然后，我们研究了可视化方法来向包括学生和专家在内的非专家解释这些看不见的现象。研究发现，每个图像都应该包含由原始变量表示的有限信息，这是有效的。流体和温度脉动之间的相位差最有效地通过使用不同颜色的线框模型的动画来表示。热流通过对控制方程的定量求解得到，并用表示热焓的虚拟粒子运动来表示。粒子的横向运动非常微妙，不像传统的定性解释机制给人的印象。可视化方法成功地显示了热流的微小横向运动对纵向换热有显著的强化作用。较少

Longitudinal heat transfer between two fluid reservoirs of different temperature is highly enhanced by fluid pulsation in capillary pipes that connect the reservoirs. The heat transfer is known to be proportional to the product of the longitudinal temperature gradient and the square of the pulsating fluid displacement from analyses for single circular pipes. Pipe bundles are used in practical applications to obtain a sufficient amount of heat transfer. There exist spaces between each three pipes in circular pipe bundles, which deteriorate the heat transfer characteristics. To avoid this disadvantage, pipes of triangular, square and hexagonal section as well as of circular on were considered. Although the triangular pipe showed the best heat transfer characteristics as a single pipe, it was cleared that the wall thickness and its heat conduction coefficient were important parameters to determine the performance as pipe bundles from the analysis under the conditions of the same cross sec … More tional area, wall thickness and fluid pulsation amplitude. The effect of wavy wall was also investigated changing the wave number of the wavy wall, its amplitude and the fluid pulsation frequency and amplitude. The heat transfer was enhanced with the amplitude of the wall waviness. The wavy wall pipes were superior to smooth ones in dynamic response of heat transfer controled by fluid pulsation amplitude and frequency.The mechanism of the heat transfer of this apparatus was investigated closely. We found a region where heat was transferred toward higher temperature end and this occurred in the region where the phase lag between the pulsations of fluid and temperature exceeded π/2. Then visualization methods have been investigated to explain these unseen phenomena to nonexperts including students as well as experts. It was found effective that each image should contain limited informations presented by primitive variables. The phase difference between the pulsations of fluid and temperature was most effectively presented by animations using wire frame model of different colors. The heat flow was obtained quantitatively solving the governing equations and expressed by the motion of virtual particles which represented enthalpy. The lateral motion of the particles was very subtle unlike the impressions given by the conventional qualitative explanation of the mechanism. The visualization method successfully showed that the small lateral motion of heat flow resulted in a significant enhancement of longitudinal heat transfer. Less