Experimental investigation of wind effect on rectangular cylinders with rounded corners

Abstract

An experimental investigation of the static pressure distribution on the square and rectangular cylinders with rounded comers is conducted. The study incorporates both the single cylinder and the group consisting of two cylinders. The test is conducted in open circuit wind tunnel at a Reynolds number of 2.87 x 104 and 4.30 x 104 based on the side dimension across the flow with uniform flow of velocity 14.2 m/s. First of all, the study is conducted on a single cylinder with various nose radius and side dimensions at zero angle of attack. The three different dimensionless nose radius are considered in the study with a view to observing the effect of the nose radius on the static pressure distribution. Then a group of cylinder is taken into consideration for the study. Each group consists of two cylinders one is front and the other is rear which are kept along the flow direction. The static pressure distribution is done on each cylinders in the group varying the inter spacing between the front and rear cylinders. At a particular dimensionless nose radius the study is done on the group. The drag coefficient which is essential to find wind load is determined from the static pressure distributions by the numerical integration method. It is observed from the results that the drag coefficient value depends on the nose radius significantly. With the rounded nose on the cylinder the drag reduces remarkably compared to that on the sharp edged cylinders, however, with further increase of nose radius, drag does not change that much. The effect of inter space is prominent observed on the inter space in the group. An empirical relation of drag coefficient as a function of dimensionless nose radius is presented in order to calculate the drag coefficient on a freestanding building.