【作者】 刘非；

【导师】 喻国良；

【作者基本信息】 上海交通大学 ， 港口海岸与近海工程， 2012， 硕士

【摘要】 自上世纪九十年代开始,国内外学者对弯曲水流中固液两相运动开展了大量研究,尤其是数值模拟的研究,并得到了一些成果,然而,弯曲水流中固液两相运动的夹角如何,尚无人涉及,有待研究。固体颗粒在弯曲水流中会由于密度不同和水流作用力的变化而产生与水流的分离运动。这种与水流的分离运动有利有弊,在多种因素的综合作用下可以衍生出多种自然灾害、险情与工业设备损毁;另外,这一特性也被广泛应用于水利、环境保护、冶矿等领域。研究这种运动特性是把握其致害规律,推进相关应用技术发展的关键。本文旨在通过数值计算和实验方法研究固体颗粒在弯曲水流中发生分离运动的特性,并提出以分离角作为量化标准的计算公式。数值部分作为辅助工具,通过4阶龙格-库塔格式求解颗粒运动方程,获得了颗粒分离运动要素的变化过程,分析讨论了各种水流作用力对颗粒分离运动的影响,并求出不同时刻颗粒运动方向与水流运动方向的分离角度,分析了影响颗粒分离角的三大主要因素。在数值计算的基础上,针对3个主要参数:颗粒粒径、密度和平台转速进行了27个不同参数组合的实验。分析了设备水平、图像观测和照片扭曲等主要误差来源,通过特定的修正方法,减小了照片扭曲产生的误差,并运用螺旋线来拟合观测数据,获得了连续有效的分离角实验数据。实验结果与数值解吻合良好。研究表明,在床面上的静止颗粒在水流作用下开始运动后,颗粒运动迅速得到发展,颗粒与水流运动方向的分离角亦迅速增大,然后随时间的推移逐步减少;颗粒运动充分发展以后的分离角与当地水流流速、水流运动曲率半径和颗粒的大小及比重有关;在实验范围内,颗粒运动的分离角最大不超过20°。最后,利用多元回归方法,提出了分离角计算公式。更多还原

【Abstract】 Since the 1990s, extensive research was carried out regarding solid-liquid two-phase movement in curvilinear flows, especially the study of numerical simulation. However, none of it was involved in deviation angle between 2-phase movements.In curvilinear flows, deviation motion of particle due to its different density and hydrodynamic force can lead to varieties of natural disaster and dangers in industrial process. However, it can be applied to water conservancy and mining industry. Studying its rule is necessary to control its damage and promote the development of corresponding technology. This thesis aims to propose a formula of deviation angle, a quantitative standard of deviation characteristics, through numerical and experimental method. As an auxiliary tool, numerical part aim to analyze the effect of hydrodynamic force on deviation angle and find out the main corresponding parameters. In case of 2D rotational flow (steady along streamline), the kinematic equation is solved through 4th order Runge-Kutta method to get the deviation angle induced by hydrodynamic forces. Based on the numerical result, 27 experiments with different particle diameter, density or rotational speed were carried out on a rotational platform. Three main errors are considered such as device’s leveling, observational error and photos’distortion. Through specific approach, the error induced by distorted photos was narrowed down to minimum. Series of effective data was achieved by fitting observed data with spiral lines. The numerical simulations were consistently compared with the experimental results. Based on the multiple regression method, a formula was proposed to predict the deviation angle. The study shows that the motion of the particle resting on the bed developed very fast after initiating its movement, the deviation angle dramatically increased and reached a peak, and thereafter decreased gradually. The maximum deviation angle did not exceed 20 degree in the present tests.更多还原