Sergio Preidikman

Converting flow-induced vibrations into electricity for low-power generation has received growing attention over the past few years. Aeroelastic phenomena, good candidates to yield high energy performance in renewable wind energy harvesting (EH) systems, can play a pivotal role in providing sufficient power for extended operation with little or no battery replacement. In this paper, a numerical model and a co-simulation approach have been developed to study a new EH device for power generation. We investigate the problem focusing on a weakly aerodynamically coupled flutter-based EH system. It consists of two flexible wings anchored by cantilevered beams with attached piezoelectric layers, undergoing nonlinear coupled bending–torsion limit cycle oscillations. Besides the development of individual EH devices, further issues are posed when considering multiple objects for realizing a network of devices and magnifying the extracted power due to nonlinear synergies and constructive interferences. This work investigates the effect of various external conditions and physical parameters on the performance of the piezoaeroelastic array of devices. From the viewpoint of applications, we are most concerned about whether an EH can generate sufficient power under a variable excitation. The results of this study can be used for the design and integration of low-energy wind generation technologies into buildings, bridges, and built-in sensor networks in aircraft structures.

Interest in the development of super-maneuverable, micro-air-vehicles has led to the re-examination of basic flight modes, particularly, those that are inspired by biological observations. The majority of experimental and numerical studies related to flapping flight have explored the relationships between the thrust coefficient (and propulsive efficiency) and wing geometry and kinematics. Relatively speaking, the wing flexibility and the interplay between kinematics and flexibility have received less attention, and currently, it remains unclear as to if they can be exploited to achieve a better performance during low Reynolds number flapping flight. To bridge this gap. the role of flexibility and fluid-structure interactions in flapping flight have been numerically investigated by using a two-dimensional, two-component wing system with a torsion spring. One of the primary outcomes of this work is that nonlinear resonances play an important role in determining the performance of a flapping wing system, mainly through the formation of leading, trailing edge, and end of stroke vortices and interactions amongst them.

A method for simulating the spontaneous, wind-excited vibrations of suspension bridges is described. The approach is based on a numerical model that treats the bridge and flowing air as elements of a single dynamic system; and all of the governing equations are integrated numerically, simultaneously, and interactively. It is shown that the present simulation predicts the same onset of flutter as the analysis of Fung. Unlike Fung’s analysis, the present analysis provides the solution in the time domain, is not restricted to periodic motions or linear equations of motion, and provides post-onset behavior as long as the effective angles of attack are not large enough to produce stall. As a consequence, the present analysis can be a very effective tool for the design of flutter-suppressing control systems. Because the equations are solved numerically, nonlinear supports do not present a problem. In the present work, it is shown how the nonlinear springs lead to limit-cycle responses.