Multi-Fidelity Uncertainty Quantification: Application to a Vertical Axis Wind Turbine Under an Extreme Gust

Designing better vertical axis wind turbines (VAWTs) requires considering the uncertainwind conditions they operate in and quantifying the e ect of such uncertainties. We studythe e ect of an uncertain extreme gust on the maximum forces on the blades of the VAWT.The gust is parametrized by three random variables that control its location, length andamplitude. We propose a multi- delity approach to uncertainty quanti cation that usespolynomial chaos to create an approximation to the high- delity statistics via a correctionfunction based on the di erence between high and low- delity simulations. The multi- delity method provides accurate statistics on the maximum forces for a small numberof simulations and the multi- delity statistics are consistent with the high- delity (CFD)statistics. We developed a practical method to simulate a gust, that changes its magnitudein the ow direction, in a CFD solver by combining the eld velocity method (FVM) andthe geometric conservation law (GCL). The ability to study the e ect of the gust with thehigh- delity (CFD) solver is crucial as the low- delity (blade element/vortex lattice) solverunderestimates the e ect of the gust on the maximum forces.