Optimal thickness distributions of aeroelastic flapping shells

Abstract

The severe weight limitations of flapping wing micro air vehicles necessitates the use of thin flexible wings, which in turn requires an aeroelastic modeling tool for proper numerical characterization. Furthermore, due to the unconventional nature of these vehicles, wing design guidelines for thrust and/or power considerations are not generally available; numerical design optimization then becomes a valuable tool. This work couples a nonlinear shell model to an unsteady vortex lattice solver, and then computes analytical design gradients: the derivative of aerodynamic force/power quantities with respect to a large vector of thickness variables. Gradient-based optimization is then used to locate the wing structure that maximizes the thrust, or minimizes the power under a thrust constraint, for a variety of shell boundary conditions. Changes in the topological features of the optimal wing thicknesses highlight important aeroelastic interactions that can be exploited for efficient flapping wings.Published by Elsevier Masson SAS.

Influence of the aspect ratio of the sheet for an electric generator utilizing the rotation of a flapping sheet

“…In this study, the UVLM was employed to model the airflow around the flexible sheet under the assumption of unsteady three-dimensional potential flow. The UVLM is a popular technique for evaluating the aerodynamic and aeroelastic characteristics of a wing because it requires a significantly reduced computational cost relative to CFD analysis (Katz and Plotkin, 2001) (Fritz and Long, 2004) (Stanford and Beran, 2013) (Abdelkefi et al, 2014).…”

“…We have also presented a numerical model to avoid these problems in previous studies (Yamano et al, 2018(Yamano et al, , 2020. In our approach, three-dimensional fluid flow was modeled using the UVLM without the above-mentioned assumption, which involves reduced computing costs compared with CFD analysis (Katz and Plotkin, 2001) (Fritz and Long, 2004) (Stanford and Beran, 2013) (Abdelkefi et al, 2014). Thereby, many parameter combinations including large deformation can be surveyed.…”

Dove: A biomimetic flapping-wing micro air vehicle

“…Research works 25,26 show that the flexibility of the membrane wing would dominate the aerodynamic characteristics, a parametric study was primarily carried out to investigate the effects of wing deformation on aerodynamic characteristics, so as to determine the rigidity distribution of the flexible wing. The preconditioned Reynold-averaged Navier-Stokes equations, based on chimera grid, 27 were developed to implement this numerical study.…”

Micro-cantilever flow sensor for small aircraft

“…Thus, UVLM requires the fluid to leave the beam smoothly at the trailing edge to satisfy the Kutta condition (Preidikman and Mook, 2000; Hall et al., 2001; Wang, 2004) and does not cover the cases of flow separation at the leading edge and extreme situations where strong beam–wake interactions take place. In spite of these restrictions, the use of UVLM remains adequate for our application of interest (Preidikman and Mook, 2000; Hall et al., 2001; Wang, 2004; Stanford and Beran, 2011).…”