Overview
This lecture is FREE to attend and starts at 18:00hrs, with refreshments from 17:00hrs.
The diameter of the turbine is determined by the water depth, but the length is limited only by the width of the flow. Unfortunately, a simple rotor with parallel blades would be too weak and flexible to resist the large fluid forces in the flow direction. However, if the turbine blades are rearranged to form a stiff, strong, triangulated truss structure, the turbine can be extended across the flow. The blades provide the stiff structure as well as providing the hydrodynamic force driving the rotor. Analysis shows that the total head drop through the turbine is an important parameter and that power coefficients can exceed the Betz limit. Power curves from tests on a 0.5m diameter, single-bay rotor in a flume, have validated the THAWT truss design. A 1 km length of 10m diameter THAWT turbines stretched across the flow could generate more than 56MW.
Prof Martin Oldfield, ASME Fellow, is an Applied Maths and Electrical Engineering graduate of Sydney University and a retired Professor in Engineering Science at the University of Oxford. As a Mechanical Engineer at Oxford, he has 35 years’ research experience in turbomachinery, aerodynamics and heat transfer. He has designed large wind tunnels and associated instrumentation and has managed major research projects for Rolls-Royce, QinetiQ and the EU. He has recently been working on tidal turbines.