Flow characteristics around circular cylinders forming square biplane grid

Abstract

There are two types of square lattice structure, biplane grid and woven screen, in order to control various industrial flow fields. In particular, the square biplane grid which consists of several cylinders arrayed at right angle is often used to make turbulence. In addition, it is proposed to apply the heat transfer enhancement effect to heat exchanger. Accordingly, it is important to reveal the flow characteristics around circular cylinders forming biplane grid. However, the flow characteristics around circular cylinders forming square biplane grid has not been fully examined. Therefore, the aim of this study is to clarify the three-dimensional flow field around the circular cylinder members forming the square biplane grid by means of the measurement of surface pressure distributions, the estimation of local drag coefficients and the visualization of path line. It is known from the previous results of two crossed circular cylinders that the flow over the separation area on the upstream cylinder invades in the vicinity of the contact point between upstream and downstream cylinders. Accordingly, it is supposed that the there-dimensional flow which is similar to the two crossed cylinders is made in the cross region of cylinder members forming the biplane grid. As a result, it was found that the flow invading in the contact region may have produced the longitudinal vortices periodically fluctuating behind the downstream cylinder of the biplane grid.