Development of an Innovative Angle-Controlling Oscillation Mechanism for Wind Tunnel Testing

The paper presents the design, development, and fabrication of an innovative motorized angle-of-attack (AoA) oscillation system controlled by a computer. This compact rotative system is designed to be used in the Northumbria University's wind tunnel, providing a choice of steady or oscillating angles for the testing of models including blades, airfoils, vehicles, etc. Thanks to a table diameter of 600mm (interchangeable for bigger models). Unlike a traditional mechanical system, it is able to conduct unsteady testing of the model by creating a user-defined angle oscillation for a variety of reduced frequencies. The rotary movement of the turntable will be achieved by a two-phase stepper motor with a resolution of 200 steps per
$\boldsymbol{360^{\circ}}$
at the maximal velocity of 3000rpm. A simple but uncluttered LabViewinterface with a motor program will control the system. The accuracy of the turntable is 2% per degree, driven by a belt transmission with a ratio of 1:1.8 which results in each motor step rotating the table by one degree. It is expected to achieve a table rotation velocity of 60 degrees per second with an oscillating frequency that can reach 16 Hertz. The turntable has a height of 76mm to reduce impact on the airflow during three-dimensional testing. During two-dimensional testing, a raised platform is built to simulate the table being flush with the tunnel floor. A compact design with minimal effect on airflow allows the system to be used in several different orientations, such as horizontally on the tunnel floor, inverted on the ceiling, or vertically on the side walls.