River Devices to Recover Energy with Advanced Materials River DREAM

This report describes the development and testing of a Galloping Hydro Electric Energy Device (GHEED) which is intended to utilize a Dielectric Elastomer Generator (DEG). The mechanical side of the GHEED includes a shape morphing element, and has been designed to convert the kinetic energy of low head and/or turbulent flows into repeating, oscillating motion. The intent is to couple this motion to a DEG, which will convert the oscillating motion into electrical energy. In this exploratory program, the experimental elements of the mechanical and electrical sides of the program were conducted in parallel; a unifying model has been created to project the potential for a combined device. The mechanical side of the GHEED was developed at the University of Pittsburgh and included: GHEED prototype design and construction, design and implementation of performance enhancing shape morphing elements, and computational fluid dynamics studies facilitating creation of the unifying model. Also described is the testing of a dielectric elastomer generator developed by Stanford Research Institute (SRI), and calibration of a model to data from that generator. In modeling, it was found that the spring rate of a dielectric elastomer generator could be linearized by the addition of an opposed mechanical phase. This arrangement simplifies analysis, and so this additional configuration was modeled. Analysis also showed that viscoelastic losses in the acrylic dielectric used in the SRI generator were undesirably large, and so additional material tests on an alternative silicone dielectric were undertaken at Artificial Muscle Inc. Generator performance based on this new material was also modeled, and the simulation was coupled to a model of a small galloping bluff body in hydrokinetic flow, calibrated to flume data. The representation was then used to size a dielectric elastomer generator suitable for a 1 kilowatt demonstration generator.