DESIGN AND IMPLEMENTATION OF A SYSTEM FOR MEASURING AN AERODYNAMIC DRAG COEFFICIENT

The research aims to design and construct a device to measure the drag coefficient for the free falling and accelerating bodies in different fluid mediums. Four main factors are know to have an effect on free falling bodies. These factors are: shape, size density of the body and density of the medium through which the body travels. In this study, spherical and cylindrical shape bodies were investigated. Carbon steel and glass spheres of diameter range (0.5-20 mm) were considered also carbon steel cylinders of l/d range (1.33, 1.375, 1.44, 1.54, 2.5, 3.33, 4) were investigated. Water and air media were used through which the falling bodies were allowed to drop. The experimental results revealed that the speed of the falling bodies increases with displacement until terminal velocity is reached. This was true for both shapes and water medium and the experimental results were found to follow the theoretical ones with insignificant variation specially at low velocities. Drag coefficient was calculated after the establishment of the terminal velocity for each body shape used in the case of free falling and hence the relation between drag coefficients and Reynolds number were determined.