title: Piezoelectric energy harvesting in internal fluid flow.
abstract: We consider piezoelectric flow energy harvesting in an internal flow environment with the ultimate goal powering systems such as sensors in deep oil well applications. Fluid motion is coupled to structural vibration via a cantilever beam placed in a converging-diverging flow channel. Two designs were considered for the electromechanical coupling: first; the cantilever itself is a piezoelectric bimorph; second; the cantilever is mounted on a pair of flextensional actuators. We experimentally investigated varying the geometry of the flow passage and the flow rate. Experimental results revealed that the power generated from both designs was similar; producing as much as 20 mW at a flow rate of 20 L/min. The bimorph designs were prone to failure at the extremes of flow rates tested. Finite element analysis (FEA) showed fatigue failure was imminent due to stress concentrations near the bimorph's clamped region; and that robustness could be improved with a stepped-joint mounting design. A similar FEA model showed the flextensional-based harvester had a resonant frequency of around 375 Hz and an electromechanical coupling of 0.23 between the cantilever and flextensional actuators in a vacuum. These values; along with the power levels demonstrated; are significant steps toward building a system design that can eventually deliver power in the Watts range to devices down within a well.
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. hjlee@jpl.nasa.gov.
authors.forename: Hyeong Jae
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. stewart.sherrit@jpl.nasa.gov.
authors.forename: Stewart
authors.initials: S
authors.lastname: Sherrit
authors.affiliation: California Institute of Technology, Pasadena, CA 91109, USA. ltos@caltech.edu.
authors.forename: Luis Phillipe
authors.initials: LP
authors.lastname: Tosi
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. Phillip.E.Walkemeyer@jpl.nasa.gov.
authors.forename: Phillip
authors.initials: P
authors.lastname: Walkemeyer
authors.affiliation: California Institute of Technology, Pasadena, CA 91109, USA. colonius@caltech.edu.
authors.forename: Tim
authors.initials: T
authors.lastname: Colonius
keywords: flow energy harvesting; fluid-structure interaction; piezoelectric; transducer