A Study in Flow Past Triangular Cylinders with different Apex Angles

Abstract

In the present investigation the effects of the magnitude and the orientation of the apex angle as well as the angle of attack on the structure of the flow past a triangular cylinder were experimentally investigated in the wind tunnel. Four isosceles triangular prisms with apex angles of and , and with identical cross-stream and spanwise dimensions were used as the experimental models. With the above-mentioned models, investigation in which the flow separation angle (equals to half the apex angle) gradually increases (for cylinders with apex facing upstream), or the effects of the afterbody gradually reduce (for cylinders with apex facing downstream) were carried out systematically. The main consequences of varying the separation angle are the changes in the vortex formation length (and hence cylinder base pressure and drag force) and the circulation of the vortices shed. The reduction in afterbody shape mainly affects the proximity of the two separated shear layers to each other and to their corresponding side faces, and consequently the cylindera??s stability to transverse translational galloping oscillation.