Experimental Study of Drag Reduction on Circular Cylinder and Reduction of Pressure Drop in Narrow Channels by Using a Cylinder Disturbance Body

Abstract

This paper present the results of drag reduction on circular cylinder and reduction of pressure drop in narrow rectangular channels by using circular disturbance body. This study focused on the phenomenon when the flow through the arrangement of the circular cylinder, separation will occur at a specific point on a circular cylinder resulting drag force. When the separation can be delayed so that the resulting drag force will be smaller. This can be done in various ways, one of which is by using a cylinder disturbance body on the upper and lower side near the bluff body. This study will be conducted in a wind tunnel experiments which have narrow channels with a square cross-sectional area of 125 mm x 125 mm and a blockage ratio of 26.4% and 36.4%. Specimens used circular cylinder with 25 mm diameter (d/D= 0.16) and 37.5 mm (d/D= 0.107) as well as the circular disturbance body with a diameter of 4 mm. cylinder disturbance body placed on the upper and lower side with the position α=200 to 600 and spacing (δ=0.4 mm) to the main circular cylinder. Reynolds number based on the hydraulic diameter of 5.21×104 to 15.6×104. The results of this research show the effect of using circular disturbance body on circular cylinder and the characteristics of fluid flow on a narrow channel square cross section. At a certain position of the circular disturbance body provide value pressure drop reduction on narrow channels and drag reduction when compared to a single circular cylinder. From the experimental data presented in this paper it is observed that the position angle of circular disturbance body to reduce drag force on a circular cylinder and reducing the pressure drop in the channel are at angle 200 and 300 for D=25 mm, and 200, 300 and 400, respectively, for D= 37.5 mm then the best reduction for both cylinders are at an angle of 300.