Low Order Turbulence Modeling Methods for MAVs Flight Environment

The effects of turbulence on Micro Air Vehicles are investigated through the combination of a fast turbulence synthesis method and a low order unsteady aerodynamic model. The turbulence synthesis method leverages a digital finite impulse response filter to allow for the generation of turbulence fields from 1-D to 3-D with easily definable statistics. An implementation of the unsteady vortex lattice method is combined with the synthesized turbulence to generate long time histories of the instantaneous effects of turbulence on airfoil loading. Spectral analysis was used on several runs to evaluate bandwidths of relevance and important behaviors. Turbulence with length scales smaller than the airfoil chord was shown to have little effect on airfoil load. Vertical force and pitching moment were both highly correlated to the vertical component of velocity while neither showed correlation to incoming turbulent velocity. The vertical force was most affected by turbulence of length scales much larger than the chord while the moment was primarily affected by turbulence with length scales on the order of chord length. These results indicate aircraft reactions to turbulence and motivate the development of a dynamic sensor for determination of turbulent vertical velocity.

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