Aeroelastic characteristics of flexible membrane wings with ceiling effect

We present a numerical study to analyze the aeroelastic characteristics of two-dimensional flexible membrane wings subjected to the ceiling effect. A body-fitted variational aeroelastic solver based on the fully coupled Navier-Stokes and nonlinear structural equations is employed to model the coupled fluid-membrane system. The coupled dynamics and the aerodynamic performance of flexible membrane wings with ceiling effect are investigated in a parameter space of angle of attack and ceiling distance. The effect of ceiling distance on the aeroelastic characteristics is examined at pre-stall, near-stall, and stall conditions. The role of flexibility in the coupled system under near-ceiling conditions is investigated by comparing with its rigid flat and cambered counterparts. The effect of no-slip and perfect slip boundary conditions of the ceiling wall is compared to quantify the momentum transport influenced by the ceiling effect. The connection between the aerodynamic loads and the membrane deformation is constructed by two scaling relations presented in our previous studies. The results indicate that the aeroelastic characteristics of the flexible membrane wings under near-ceiling conditions are adjusted from three aspects, namely, (i) the gap to the ceiling, (ii) the wing flexibility, and (iii) the ceiling boundary condition. This study represents a step toward an improved understanding of the aeroelastic characteristics of flexible membrane wings under ceiling conditions with different boundary layer flows. These findings can facilitate the development of high-efficiency bio-inspired micro-air vehicles that have robust flight stability and can perform missions in confined spaces.