Exploiting stiffness nonlinearities to improve flow energy capture from the wake of a bluff body

Ali H. Alhadidi, Hamid Abderrahmane, Mohammed F. Daqaq

Research output: Contribution to journalArticlepeer-review

Abstract

Fluid–structure coupling mechanisms such as wake galloping have been recently utilized to develop scalable flow energy harvesters. Unlike traditional rotary-type generators which are known to suffer serious scalability issues because their efficiency drops significantly as their size decreases; wake-galloping flow energy harvesters (FEHs) operate using a very simple motion mechanism, and, hence can be scaled down to fit the desired application. Nevertheless, wake-galloping FEHs have their own shortcomings. Typically, a wake-galloping FEH has a linear restoring force which results in a very narrow lock-in region. As a result, it does not perform well under the broad range of shedding frequencies normally associated with a variable flow speed. To overcome this critical problem, this article demonstrates theoretically and experimentally that, a bi-stable restoring force can be used to broaden the steady-state bandwidth of wake galloping FEHs and, thereby to decrease their sensitivity to variations in the flow speed. An experimental case study is carried out in a wind tunnel to compare the performance of a bi-stable and a linear FEH under single- and multi-frequency vortex street. An experimentally-validated lumped-parameters model of the bi-stable harvester is also introduced, and solved using the method of multiple scales to study the influence of the shape of the potential energy function on the output voltage.

Original languageEnglish (US)
Pages (from-to)30-42
Number of pages13
JournalPhysica D: Nonlinear Phenomena
Volume337
DOIs
StatePublished - Dec 15 2016

Keywords

  • Bi-stable
  • Energy harvesting
  • Vortex
  • Wake-galloping

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Mathematical Physics
  • Condensed Matter Physics
  • Applied Mathematics

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