ScholarWorks@중앙대학교

초록

Flutter-based wind energy harvesters often suffer from limited efficiency under low-to-moderate wind conditions, hindering their application in distributed power systems. To address this challenge, we propose a stall flutter based piezoelectric harvester featuring a diamond-shaped airfoil with endplates. This design introduces a static angle of attack to induce stall flutter and leverages 1:1 internal resonance in conjunction with multi-point flow separation to enhance energy conversion efficiency. A theoretical framework is established using the extended Hamilton’s principle, the Galerkin method, and the expansion theorem. A two-step modal analysis is applied to discretize the continuous system and analyze its dynamic and energetic responses. Nonlinear dynamic behaviors are examined through the perturbation method and harmonic balance technique, revealing the presence of limit cycle oscillations and hysteretic phenomena. To elucidate the aerodynamic enhancement mechanisms, computational fluid dynamics and finite-time Lyapunov exponent analyses are conducted. These demonstrate that multi-point flow separation facilitates dynamic stall vortex formation, which strengthens the interaction between the elastic structure and aerodynamic forces. Experimental validation is performed using an optimized prototype, showing strong agreement with theoretical predictions. The proposed harvester achieves a power density of 167.1 W/m3 at 9 m/s, significantly outperforming conventional designs. This work not only presents a unified theoretical–experimental framework for analyzing stall-flutter-based harvesters but also underscores the crucial role of nonlinear flow–structure interactions in optimizing energy harvesting efficiency. The methodologies and findings contribute valuable insights for the design of compact, self-powered devices and advance the development of next-generation sustainable energy harvesting systems.

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