基于稠密气体分子动力学和气固两相流体动力学，建立流化床稠密气固两相离散颗粒运动-碰撞解耦模型，采用直接模拟蒙特卡罗方法（DSMC）模拟颗粒间的碰撞，采用考虑颗粒脉动流动对气相湍流流动影响的大涡模拟（LES）研究气相湍流，单颗...基于稠密气体分子动力学和气固两相流体动力学，建立流化床稠密气固两相离散颗粒运动-碰撞解耦模型，采用直接模拟蒙特卡罗方法（DSMC）模拟颗粒间的碰撞，采用考虑颗粒脉动流动对气相湍流流动影响的大涡模拟（LES）研究气相湍流，单颗粒运动满足牛顿第二定律，颗粒相和气相相间作用的双向耦合由牛顿第三定律确定。数值模拟流化床中颗粒流动以及气泡的生成、长大和破碎过程，获得颗粒轴向和径向速度的概率密度分布，及颗粒浓度分布。计算结果表明床内气泡的形成造成床内颗粒的循环，使得流化床内颗粒具有不同的轴向和径向脉动速度，颗粒分速度分布近似服从高斯分布。颗粒温度随颗粒浓度增加，达到最大值后，随颗粒浓度增大而下降。流化床颗粒浓度脉动主要是低频部分，高频分量较低，表明在流化床内颗粒浓度脉动频率低，能量高，颗粒浓度脉动主频率为0．04～1．0Hz，其值与Pain et al．获得的颗粒浓度脉动主频率基本吻合。展开更多
An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For thi...An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For this new system, most of collision energy is absorbed through the displacement of floating platforms. In order to illustrate the validity of the system, a series of model tests were conducted at a scale of 1:40. The coupled motion characteristics of the floating mooring platforms were discussed under regular and irregular waves, and the influences of wave direction and other characteristics on dynamic response of the system were analyzed. The results show that the mooring system is safest at 0° of wave incident angle, whereas the most dangerous mooring state occurs at 90° of wave incident angle. Motion responses increase with the increase of wave height, but are not linearly related to changes in wave height.展开更多
文摘基于稠密气体分子动力学和气固两相流体动力学，建立流化床稠密气固两相离散颗粒运动-碰撞解耦模型，采用直接模拟蒙特卡罗方法（DSMC）模拟颗粒间的碰撞，采用考虑颗粒脉动流动对气相湍流流动影响的大涡模拟（LES）研究气相湍流，单颗粒运动满足牛顿第二定律，颗粒相和气相相间作用的双向耦合由牛顿第三定律确定。数值模拟流化床中颗粒流动以及气泡的生成、长大和破碎过程，获得颗粒轴向和径向速度的概率密度分布，及颗粒浓度分布。计算结果表明床内气泡的形成造成床内颗粒的循环，使得流化床内颗粒具有不同的轴向和径向脉动速度，颗粒分速度分布近似服从高斯分布。颗粒温度随颗粒浓度增加，达到最大值后，随颗粒浓度增大而下降。流化床颗粒浓度脉动主要是低频部分，高频分量较低，表明在流化床内颗粒浓度脉动频率低，能量高，颗粒浓度脉动主频率为0．04～1．0Hz，其值与Pain et al．获得的颗粒浓度脉动主频率基本吻合。
基金the support of the National Natural Science Foundation of China (Grant No. 51309179)the National High Technology Research and Development Program of China (863 Program, Grant No. 2012AA051705)+2 种基金the International S&T Cooperation Program of China (Grant No. 2012DFA70490)the State Key Laboratory of Hydraulic Engineering Simulation and Safety (Tianjin University)the Tianjin Municipal Natural Science Foundation (Grant Nos. 14JCQNJC07000 and 13JCYBJC19100)
文摘An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For this new system, most of collision energy is absorbed through the displacement of floating platforms. In order to illustrate the validity of the system, a series of model tests were conducted at a scale of 1:40. The coupled motion characteristics of the floating mooring platforms were discussed under regular and irregular waves, and the influences of wave direction and other characteristics on dynamic response of the system were analyzed. The results show that the mooring system is safest at 0° of wave incident angle, whereas the most dangerous mooring state occurs at 90° of wave incident angle. Motion responses increase with the increase of wave height, but are not linearly related to changes in wave height.
