Design of a Fan-Based Test Stand for Evaluating Multicopter Handling in Turbulent Flow

With the innovation of eVTOL rotorcraft the need to analyze how turbulence-induced disturbances from orthogonal flow affect various rotorcraft configurations outside of simulations have grown significantly. To investigate the behavior of this type of flow and how it interacts with various rotorcraft configurations, a turbulent inducing test stand was designed and constructed. The test stand will have two walls of computer fans arranged in an L-shape frame, creating wind gusts that simulate the non-linear turbulent wind experienced by eVTOL. This also aids the Eagle Flight Research Center (EFRC) in their efforts to better understand how disturbances affect the handling qualities of both quadcopter drones and down-scale rotorcraft models as the wind gust can induce disturbances on the model. This report primarily focuses on the construction of the test stand and its independent capability to generate wind. To observe this four cases were investigated. The vertical gust case showed that a single direction wind gust grew weaker as measurement probe travelled further away from the generation wall. By adding a horizontal gust wall for Case 2 the overall wind speed within the flow field greatly increased while alternating the wind direction towards a general 45-degree angle. Alternating the constant wind speed of the horizontal gust wall in Case 3 decreased the overall wind speed and showed how varying wind speeds would cause a more erratic series of wind gust vectors than in previous cases. By using a time varying sine-wave pattern for Case 4 there was a sharp drop in average wind gust speed since the fans never had enough time to truly build up its wind speed like in case 1. This case also showed how at the same point in the PWM cycle different points in the flow field would alternate between the peak and valley of each fan’s respective air speed. All four cases shown an ability to overcome Phantom 4’s max air resistance but only cases 1 to 3 came close to overcoming the Mavic 3’s max air resistance.