LABORATORY TESTS OF THE AERODYNAMIC DRAG COEFFICIENT OF THE FLAG AS A BODY WITH LOW STIFFNESS

Abstract

The shape and drag of bodies with small stiffness may change during the airflow. This problem refers to such bodies as flags, bands, banners, flapping sails as well as blades and cables which vibrate due to the flow.

Laboratory tests carried out to point out the aerodynamic drag coefficient of a flag are discussed in this article. The laboratory tests were carried out in an aerodynamic tunnel at different airflow velocities for flags with different dimensions made of fabrics of different roughness and stiffness. The drag coefficient value decreases with the increasing airflow velocity. The drag coefficient is higher for materials with higher roughness. The drag coefficient value is also influenced by the fabric stiffness and kind of edge.

Great engineering importance to the stability of a structure (e.g. a flag mast) and the safety of nearby persons and buildings are attached to the analysed problem.