Multi-Fidelity Approach to Predicting Multi-Rotor Aerodynamic Interactions

Recent years have seen a growing interest in large electric multirotor aircraft for urban air mobility, commercial package delivery, cargo, and military applications. This has led to efforts that aim to model the interactional aerodynamics of rotors operating in close proximity and its impact on performance. While computational fluid dynamics can accurately characterize the physics of multirotor interaction, in most cases it is too computationally demanding for performing studies over a range of parameters. On the other hand, lower-fidelity models approximate the underlying physics and are computationally inexpensive, but are often imprecise in predicting the fields of interest. In this study, we present a multifidelity approach that inherits the accuracy of a high-fidelity method, while retaining the computational efficiency of a low-fidelity model. With this approach, the low-fidelity model is used to span the entire space of parameters and identify key parameter values to perform high-fidelity simulations. A few selected high-fidelity simulations performed at these parameter values are then used in a lifting procedure to determine multifidelity solutions at other parameter values. In this paper we apply this strategy to determine the lift and drag distributions of a two-rotor assembly as a function of the longitudinal and vertical distance between them. We conclude that this strategy can substantially improve upon the low-fidelity results.