Characterization of flow through an array of cylinders modeling Marine Hydrokinetic support structures

The flow around an array of vertical solid surface mounted cylinders is characterized. These cylinders model the support structures used for a Marine Hydrokinetic (MHK) device. MHK devices extract the kinetic energy of flowing water and use it to turn an electrical generator. Array configuration is thought to contribute to performance and the amount of extractable power. For example an offset array might extract more energy than a side-by-side array. The offset array could extract more energy from the flow by having the wakes of the upstream structures funnel the incident flow, increasing kinetic energy flux onto a downstream turbine. The testing of an array of cylinders is conducted in a 9.75 m long, 1.22 m wide, and 0.38 m deep open channel flume located in the Environmental Fluid Mechanics and Hydraulics Laboratory (EFM&HL) at Bucknell University. The velocity flow field is measured, using an Acoustic Doppler Velocimeter (ADV), both upstream and downstream of a single cylinder to evaluate wake properties. These wake properties are then applied to a varying array of cylinders where power estimates from the flow field are made in front of the downstream cylinder. It has been discovered that as the cylinders move farther than six diameters upstream the available power remains constant. Additionally there is an optimal spacing of the cylinders somewhere less than four diameters upstream.