竖置管流中液固两相脉动特性和颗粒浓度分布

DISTRIBUTIONS OF THE FLUCTUATIONS OF EACH PHASE AND THE PATICLE CONCENTRATION OF LIQUID-SOLID FLOW IN A VERTICALLY SET DUCT

利用激光多普勒分相测量技术，考察了液固两相自下而上通过竖置矩形管时，固、液两相的时均速度、流向及横向的脉动强度和颗粒相的相对浓度分布，证实了颗粒浓度的横向分布主要取决于颗粒的横向脉动强度分布（即ｎ＿ｐｖ＿ｐ～＇２＝常数）的分析结果．

The distribution of particle phase concentration in two-phase flows in a vertically set duct can be studied by using two--fluid model or diffusion model. The same result 'n_p.v_o~'2=constant' is deduced from both models. In the two--fluid model, the principle of force equilibrium is applied for each phase. In a steady fully developed pipe flow the inertial force is zero and there are no other external force on particle phase along the transverse direction besides the particle partial pressure caused by the fluctuation of particles, so a zero gradient of particle pressure, i.e. m_n_p.v'2. =constant, can be resulted from the momentum equation. In the diffusion model, the concentration distribution is determined by diffusion process. For an steady fully developed pipe flow, an equilibrium among the diffusions caused by various diffusion potentials is reached. There are two main diffusion potential: concentration gradient and fluctuation intensity gradient of particles. The equilibrium between the two diffusion potentials + 1 e;s lip Of V;z Uk deduced. Using two-phase velocity separation technique of LDV, the distributions of averaged velocity, the steamwise and traverse fluctuation velocities of each phase and the relative concentration of particles in a liquid--solid concurrent upward flow in a vertically set duct are completed. It is confirmed that the traverse concentration distribution of particles in fully developed sections depends mainly on the distribution of the intensity of traverse fluctuation and that 'n.v;z =constant'.