Prof. Martin Wosnik, Mechanical Engineering Department, from University of New Hampshire will be giving the ME seminar entitled “Marine Hydrokinetic Energy Conversion Research – from the Laboratory to Open Water Test Sites.”
ABSTRACT:
Research related to marine hydrokinetic (MHK) energy conversion will be presented. The work spans multiple scales – related to “Technology Readiness Levels” defined by DOE – ranging from research on hydrofoil sections, to systematic evaluation of turbines and wake measurements in a large cross-section tow tank, to open water turbine deployments at a tidal energy test site. A low-drag test bed for marine hydrokinetic turbines that allows measurement of turbine rotor performance and overall thrust on the turbine was developed for an 8’ x 12’ cross-section tow tank. Studies of cross-flow axis turbines provided insights into the physical principles of operation of this class of turbines; including the effects of waves and turbulence. Turbine performance is generally enhanced by progressive waves, but waves can also cause stalling at higher tip speed ratios compared to the steady case. Grid turbulence can enable cross-flow axis turbines to operate at lower tip speed ratios while not decreasing maximum power coefficient, but increasing thrust (drag) on the turbine slightly. Performance of a cross-flow axis turbine in the wake of an upstream obstruction, e.g., in a cylinder wake is highly dependent on the cylinder’s cross-stream location, ranging from benign to detrimental. A new, highly modular and instrumented physical scale model of a Reference Vertical Axis Turbine (RVAT) is under development. A newly renovated high speed water/cavitation tunnel is used for hydrofoil research: to obtain performance data and establish cavitation criteria for uni-and bi-directional hydrofoil sections from MHK turbine blades, including the validation of cavitation inception models for MHK turbines. Open-water deployments of MHK turbines will be discussed, including cross-flow axis and un-ducted and ducted in-stream axis turbine configurations.
A brief overview of the test sites and physical infrastructure at UNH-CORE will be given. CORE’s physical infrastructure is unique in terms of proximity, ease of access, and favorable test site characteristics. It consists of the Chase Ocean Engineering (OE) Laboratory with wave/tow tank, engineering tank and water/wind tunnels, the Tidal Energy Test Site at General Sullivan Bridge, the UNH Pier and the AMAC/wave and offshore wind energy test site. The FERC-permitted Tidal Energy Test Site has currents of greater than 4 knots (max. 5 knots) and is a large-scale test site that can accommodate turbines up to 4 meter (13 ft) in diameter. The research-permitted offshore test site is located in state waters at the UNH Atlantic Marine Aquaculture (AMAC) site in 170 ft (52 m) of water approximately 6 miles from the New Hampshire coast, and is a full-scale wave energy test site and a scaled offshore wind energy test site. A mooring grid was successfully deployed under extreme New England winter conditions for the past 10+ years. Existing and newly developed infrastructure, including support vessels, and the off-the shelf availability of environmental and survey data enable very cost-effective open water test sites.