Experimental investigation of wind effect on pentagonal and hexagonal staggered cylinders

Abstract

In this research work, an experimental investigation of wind effect on pentagonal and hexagonal staggered cylinders was carried out. The study was performed on both the single cylinder and the group consisting of three cylinders, arranged in staggered form, one pentagonal cylinder in the upstream and another two hexagonal cylinder in the downstream side. The test was conducted in an open circuit wind tunnel at a Reynolds number of 4.22 x 104 based on the face width of the cylinder across the flow direction in a uniform flow velocity of 13.5 m/s. At first experiment, the test was carried out on a single hexagonal cylinder at various angles of attack from 0° to 50° at a step of 10°. The surface static pressures at the different locations of the cylinder were measured with the help of inclined multi-manometers. Then the test was carried out on a single pentagonal cylinder at various angles of attack from 0° to 72° at a step of 9°. After that the group of three cylinders was taken into consideration for the study and the surface static pressures were measured for various transverse spacing of 2D, 3D, 5D and longitudinal spacing of 1D, 2D, 4D, 6D, 8D, where D is the width of the cylinder across the flow direction. In each case, the wind velocity was kept constant at 13.5 m/s. The pressure coefficients were calculated from the measured values of the surface static pressure distribution on the cylinder. Later the drag and lift coefficients were obtained from the pressure coefficients by the numerical integration method. The results will enable the engineers and architects to design buildings more efficiently. Since the results were expressed in the non-dimensional form they might be applied for the prototype building.