Mehr, Judd; Alvarez, Eduardo; Cardoza, Adam; Ning, Andrew (Brigham Young University)
Faculty Advisor: Ning, Andrew (Brigham Young University, Mechanical Engineering)
Wind power is an attractive alternative energy source because it is sustainable, clean and cost effective. However, wind energy is difficult to harvest because wind is irregular, seasonal, and often far away from urban areas. Several organizations have sought to solve this problem by designing wind harvesting aircraft, called windcraft. Windcraft are aircraft that are tethered to the ground, propel themselves into the air, enter steady flight in a crosswind, and allow the propellers to spin freely. The wind keeps the windcraft aloft and forces the propellers to turn backwards, turning them into turbines. Power generated from the turbines is sent down the tether and stored. Windcraft provide several advantages beyond those of conventional wind turbines, including high portability due to its smaller weight.
This research employs aerodynamic analysis to determine the forces on the turbines and lifting surfaces of a windcraft modeled after the Makani M600, an 8-rotor prototype produced by Makani Technologies. The analysis is a combination of modeling methods with varying fidelity, including the vortex lattice, vortex particle, and blade element momentum methods. The vortex lattice method models the lifting surface as a sheet of vortices that have the same capability to push on the oncoming flow as the lifting surface would. The vortex particle method uses a set of discretized fluid motion equations in a form that allows for the solution of the strength of the vortex at each point in the flow. The blade element momentum method uses two theories, the blade element theory and the momentum theory, to calculate the power, thrust and axial air velocity of a propeller or turbine. The modeling methods are validated by using experimental data from The Mexico Project and NASA. We implement basic design space exploration to display this model's compatibility with design optimization.