Modelling and Optimisation of Arrays of Novel Bio-Mimetic Energy Harvesters. Energy: Fluid Dynamics and Aerodynamics

Lead Research Organisation: University of Warwick
Department Name: Sch of Engineering

Abstract

Research Areas: Energy: Fluid Dynamics and Aerodynamics.
Energy harvesting is a promising technology for converting environmental energy to electricity. To make harvesters widespread, it is crucial to increase their efficiency. The room for improvement lays first, in getting maximum mechanical energy from the environment and second, in the efficient conversion of mechanical energy to electricity. This project for the first time suggests using a bio mimetic harvester imitating an aspen leaf as a way of harnessing the wind energy. The device in question is a fluttering plate which utilises coupling between translational and rotational degrees of freedom to undergo high amplitude oscillations, even when the wind speed is low. To generate electric energy from this movement, piezoceramic actuators are used. The main problem with piezoceramic generation is that individual devices produce a low voltage, alternating current output, meaning that nearly all of the energy from such devices is lost on conversion to useful dc current, losses are due to a voltage drop across diodes in the rectifier. The above makes real world application of the harvesters challenging. To resolve the problem, harvester arrays will be deployed, in which the leaves will be designed to move synchronously, increasing the voltage output, and therefore making the inherently lossy conversion process much more efficient thus opening up the possibility of making a practical device for this form of energy harvesting. Applications for such technology are widespread from military facilities to domestic gas flow meters. Despite extensive activity in the area of Energy Harvesting over the past several years, most studies concentrate on trial-and-error testing of certain configurations with little attention paid to thorough academic investigation of the systems behaviour. The aspen leaf type plate displays dynamic behaviour resembling the one known as the aeroelastic flutter of aircraft wing. Adaptation of existing knowledge to optimisation of the harvester will be the first step towards construction of an effective device. Overall, the programme aims at development of arrays of bio mimetic fluid elastic energy harvesters resembling a trembling aspen leaf. The proposed study is an early stage project of high academic significance. The research objectives are as follows.
a. Experimentally study oscillations of an individual aspen leaf type flutter under various flow conditions and construct the corresponding mathematical model in the spirit of dynamical systems. Design a nonlinear harvester with a stable amplitude or frequency response over a broad range of ambient wind conditions.
b. Connect individual harvesters into arrays and investigate both hydrodynamic and structural interaction between the elements in order to optimise the systems performance. The achieved degree of harvester synchronisation in an array will be related to needs and efficiency of piezoceramics based electricity generation.
c. Validate developed models by wind tunnel tests when the system is exposed to both steady flow and grid turbulence.
d. Results of the proposed experimental and modelling programme will be published to provide a basis for an EPSRC grant application. Simultaneously, commercial feasibility of deployment of harvesting arrays will be comprehensively considered.

Select the research outcome from the themes:
1 - Energy
2 - Fluid Dynamics and Aerodynamics

Publications

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Tucker Harvey S (2019) A galloping energy harvester with flow attachment in Applied Physics Letters

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509796/1 30/09/2016 29/09/2021
1738460 Studentship EP/N509796/1 02/10/2016 30/03/2020 Sam Tucker Harvey
 
Description The research conducted within the project has resulted in the development of an alternative tip geometry for a galloping energy harvester which is promising for providing greater efficiencies and output power than previously considered geometries. Dissimilarly to many other galloping geometries, the flow on the rear face of the geometry is found to become attached when the tip velocity is high enough. The findings have been published in Applied Physics Letters.
Exploitation Route The development of a new tip geometry for a galloping energy harvester may lead to the development of more efficient galloping energy harvesters. This could provide improved power solutions for autonomous electrical devices, such as those in wireless sensor networks.
Sectors Aerospace, Defence and Marine,Electronics,Energy