迪恩涡影响弯管流体运动能量耗散的数值研究

Numerical simulation of Energy dissipation by Dean Vortices in curved pipes

生态农业设施中存在大量的弯管,无论是气态还是液态物质在弯管中都存在大量的能量消耗,降低能耗是农业节能减排的重要环节之一.在笛卡尔坐标系下,利用数值方法对弯管流动能量耗散进行公式描述.在此基础上以不同几何尺寸的弯管为例,从迪恩涡的影响因素(弯管几何尺寸和离心力)出发对弯管中流体运动的能量耗散进行数值模拟,并得出了能量耗散随迪恩数的变化曲线.为了更精确地描述迪恩涡对能量耗散的影响,借助有限体积法(FVM)模拟管内流场,并采用带旋流修正的realizable k-e双方程模型和SIMPLE算法来求解控制方程组.研究结果表明:r/Rc越大,能量耗散越显著;在层流区和过渡区由离心力所引起的能量耗散相对较低,而在湍流区剧增;迪恩数以5 000为分界点,小于5 000时能量耗散呈一定规律变化,而大于5 000时能量耗散急剧增大.

Mathematics descriptions of the energy dissipation of fluid motion in curved pipes were performed under Cartesian Coordinates by means of numerical methods.On the base of the mathematics description,numerical simulation was carried out to study the energy dissipation from the influencing factors of Dean Vortices（geometry size and centrifugal force）,and the relationship between Dean Number and energy dissipation was analyzed afterward.During the simulation,the Finite Volume Method,SIMPLE algorithm and realizable k-e equations were adopted to solve the Dean Vortices more precisely.The results showed that the energy dissipation increased with the geometry size r/Rcand the centrifugal force.And the energy dissipation varied according to certain rules before the Dean number reached 5 000,while increased significantly when Dean numbers were larger than 5 000.