FLUID FLOW AROUND THREE CIRCULAR CYLINDERS HAVING DIFFERENT DIAMETERS CLOSELY ARRANGED IN LINE

摘要

In the previous paper related to the H2 rocket of Japan, aerodynamic forces acting on three circular cylinders having different diameters closely arranged in line were clarified. In this paper, the fluid flow characteristics around the three cylinders were investigated as follows: Flow visualization were carried out by using a smoke tunnel and an oil-film method, and the r.s.m. fluctuating pressure distribution and velocity of the jet from the gap of the cylinders were measured. For an attack angle α = 60 ～70°, the shear layer separated from the main cylinder reattaches and adheres to the rear surface of the cylinder beyond 210° by a Coanda effect. From the characteristics of the wake of the cylinders at a > 60°, the three cylinders can be assumed to be a rectangular cylinder with round corners and two slits.