مهندسی مکانیک شریف (Dec 2023)
Rotor Design And Performance Study Of An Airborne Wind Energy System With Flight Dynamics Simulator
Abstract
Airborne wind energy system (AWES) is a novel approach in wind energy harvesting. It has several advantages against conventional horizontal axis wind turbine (HAWT), like using less material and thus lower manufacturing cost, higher efficiency, stable electricity output and higher capacity for energy harvesting. It is obviously embedding a complex control system which makes the appropriate flight trajectory for the vehicle. These systems need to be carefully designed so using virtual flight simulators in design process is crucial. The main components of a typical AWES are: tether, flyer, and rotors. The flyer is designed to have a tether-constrained flight across the wind in a circular path. Consequently, the mounted rotors on the flyer’s wings will capture energy and this mechanical/electrical energy would be sent back to the ground via the same tether. It is notable that the flight path and the special design of the flyer, would make it capable to have a sustained motion in the circular loop with no energy consumption. A tethered drone equipped with several rotors is an example of such devices, already has been built and tested. In previous literature, the flight simulators usually contain some simple aerodynamic models for predicting the forces and moments generated by the rotors. It is derived by constant aerodynamic coefficients. In the current study, it has been developed a flight simulator for a typical AWES having onboard rotors. To make this flight simulator more accurate and to improve its fidelity in different environmental conditions, proper estimation of the external forces, particularly the aerodynamic forces and moments, seems to be necessary. Therefore, toward developing a high-fidelity simulator, Lagrangian dynamics and a new algorithm for estimation of the rotor aerodynamics, has been utilized. This new method is shown to have more accurate approximations of the system performance and also better description of the vehicle trajectory. By this framework, one could design optimized blades of the rotors and also the rotors arrangement. Implementing the new simulator, a single drone, as the flyer in AWES, having 3m wing span, would experience 40 percent improvement in the average power extracted which is near 2 KW.
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