SHARPy: A dynamic aeroelastic simulation toolbox for very flexible aircraft and wind turbines

Abstract

Aeroelasticity is the study of the dynamic interaction between unsteady aerodynamics and structural dynamics on flexible streamlined bodies, which may include rigid-body dynamics. Industry standard solutions in aeronautics and wind energy are built on the assumption of small structural displacements, which lead to linear or quasi-linear theories. However, advances in areas such as energy storage and generation, and composite material manufacturing have fostered a new kind of aeroelastic structures that may undergo large displacements under aerodynamic forces.In particular, solar-powered High-Altitude Long-Endurance (HALE) aircraft have recently seen very significant progress. New configurations are now able to stay airborne for longer than three weeks at a time. Extreme efficiency is achieved by reducing the total weight of the aircraft while increasing the lifting surfaces' aspect ratio. In a similar quest for extreme efficiency, the wind energy industry is also trending towards longer and more slender blades, specially for off-shore applications, where the largest blades are now close to 100-m long.These longer and more slender structures can present large deflections and have relatively low frequency structural modes which, in the case of aircraft, can interact with the flight dynamics modes with potentially unstable couplings. In the case of offshore wind turbines, platform movement may generate important rotor excursions that cause complex aeroelastic phenomena which conventional quasi-linear methods may not accurately capture.

Modal-Based Nonlinear Estimation and Control for Highly Flexible Aeroelastic Systems

“…The aerodynamic model of choice consists of an unsteady vortex lattice method (UVLM) formulation. This model has been implemented in the aeroelastic simulation tool SHARPy [24], developed in-house and available as open-source. It is described in detail in [19,25,26] and we therefore keep this section brief to explain only the details of the linearised description and the coupling process with the structural model.…”

Unsteady and three-dimensional aerodynamic effects on wind turbine rotor loads

“…SHARPy stands for Simulation of High Aspect Ratio Planes in Python [25] and it is an aeroelastic code developed by the authors in collaboration with the team in Imperial College London [26,27]. The aerodynamics are captured with an UVLM [24] that accounts for three-dimensional and unsteady effects but neglects viscosity, compressibility and body thickness.…”

Proof of Concept for a Hardware-in-the-Loop Nonlinear Control Framework for Very Flexible Aircraft

“…SHARPy (Simulation of High Aspect Ratio aeroplanes and wind turbines in Python) is a nonlinear aeroelastic simulation toolbox developed at Imperial College and available under open-source licence [14]. At its core, SHARPy couples a nonlinear beam solver with an unsteady aerodynamic model based on potential flow assumptions using a Block Gauss-Seidel iteration scheme [16].…”

“…1 for two example simulation snapshots). SHARPy [14] employs fully nonlinear structural and aerodynamic solvers, based on geometrically exact beams and an unsteady vortex lattice, respectively. This setup, with its realistic plant-model mismatch and limited sensors, provides a plausible and challenging environment that will be used to demonstrate the robustness of the control system.…”