MEMS 411: DBF Wind Tunnel

Design, Build, Fly (DBF) is a student-run engineering team at Washington University in St. Louis (WUSTL) that designs aircraft for flight competitions. Before assembling the final product, DBF runs numerous simulations on prototypes to understand the effects of drag and lift on the designed shape. The lift and drag parameters are important to aircraft design, as DBF hopes to optimize flight performance during competitions. However, simulations require computational power, are theoretical at best, and may inaccurately represent real-life situations. Preferably, DBF can use physical testing that captures prototype performance with more qualitative details. Senior Design Group Z approaches DBF's needs by designing a transportable wind tunnel. Wind tunnels are enclosed tubes that allow the wind to blow through while holding a scaled-down aircraft (airfoil) in the test section. DBF members can measure the aerodynamic behavior of the airfoil as it encounters the wind. For example, as the wind hits the airfoil, it splits into streamlines based on the shape, and smoother streamlines will reduce fuel consumption. Qualitative data from wind tunnel experiments will provide DBF with an effective approach to designing aircraft shapes. Group Z has manufactured a wind tunnel out of metal, with a 1 ft x 2 ft testing chamber for airfoil. The testing chamber is transparent on one side, allowing DBF members to observe aerodynamic characteristics as the wind approaches the airfoil. The wind is blown through with a box fan, which passes through a laminar mesh to reduce turbulence. DBF members can adjust the angle of attack of the airfoil through a discrete gear system. To visualize flow, a fog machine is attached to a PVC rod near the airfoil. The weight of the wind tunnel is around 40 lb with detachable parts, so DBF can easily transport the wind tunnel from the studio to the outdoors. In general, the wind tunnel provides DBF with an effective measure to observe flow separation and pattern for different airfoil models.