Data base accumulation for gas-liquid two-phase flow structures based on a construction of PIV parallel computation station

本文建立了一个粒子图像测速（PIV）并行计算系统，并将其应用于多相流湍流结构的分析。因此，总结如下：a；我们开发了一种新的PIV与CFD混合系统，即求解Navier Stokes方程的数值分析技术与PTV的VGT （Velocity Gradient Tensor）技术相结合的系统，证实了该混合系统可以计算Savonius型风力机周围的压力场。用三维PTV分析了气泡流动中A-2气泡与气泡的相互作用。很明显，引力在垂直方向上起作用，排斥力在水平方向上起作用。本文提出了一种新的反分析方法，并将其应用于高空隙率条件下的气泡流动，从而开发了一种利用反分析方法计算PIV/PTV测量液相流场的新技术。针对气液两相流的湍流结构分析：B-1构建了一种高速高分辨率视频摄像机与剪切应力传感器同步的新系统，并结合PIV测量结果阐明了壁面滑动气泡流的摩擦阻力修正机理。讨论了同轴双圆柱间隙中Taylor-Couette气泡流动的有效粘度、湍流特性和附加粘度，并对环形涡向螺旋涡的过渡现象进行了可视化和讨论。利用新型浅焦PTV系统测量了靠近平壁面的气液两相流边界层B-3型雷诺应力分布，讨论了两相流边界层内雷诺应力与摩擦减阻之间的关系。为了研究螺旋管中气泡流和段塞流的湍流结构，研制了一种新的CT图像测量系统。结果发现并讨论了由于离心力对两相流和气泡分布的影响而形成的二次流。以上结果均在参考文献Less所述的学术期刊上发表25篇论文

The present research has been carried out to construct a system of PIV (Particle Image Velocimetry) as a parallel computing station, and has been applied to analyze turbulent structures in multiphase flows. As a result, the following remarks were concluded ;A. Concerning construction of PIV parallel computing station :A-1 After we developed a new hybrid system of PIV and CFD which was a combined system consisting numerical analysis technique for solving Navier Stokes equation and VGT (Velocity Gradient Tensor technique for PTV, it was confirmed that the hybrid system could compute the pressure field around a Savonius type of wind turbine.A-2 Bubble-bubble interaction in bubbly flows were discussed with 3-D PTV. It was made clear that attractive forces were acted in the vertical direction and exclusive forces were acted in the horizontal direction.A-3 A new inverse analysis has been devised and applied to bubbly flows at high void fraction, and then a new technique for computing liquid … More phase flow field from PIV/PTV measurement using the inverse analysis has been developed.B. Concerning analysis of turbulent structure of gas-liquid two-phase flows :B-1 A new system for synchronizing a high speed high resolution vide camera and a shear stress sensor was constructed, and the friction drag modification mechanisms in wall sliding bubbly flows were elucidated with PIV measurement results.B-2 Effective viscosity, turbulent flow characteristics and additional viscosity were discussed in Taylor-Couette bubbly flows in a gap between coaxial double circular cylinders, and then the transition phenomenon from ring vortex to spiral vortex was visualized and discussed.B-3 Reynolds stress distribution in boundary layers of gas-liquid two-phase flows close to the flat wall was measured using a new shallow focal PTV system, and consequently the relation between Reynolds stress and friction drag reduction in the boundary layer of the two-phase flow was discussed.B-4 In order to elucidate the turbulent structures of bubbly flows and slug flows in a helical coil tube, a new CT image measurement system was developed. As a result, formation of secondary flows due to the centrifugal force effects on the two-phase flows and bubble distribution were newly found and discussed.All the above results were published as 25 papers in the academic journals described in the references Less