Challenge
The conversion of the kinetic energy of a flow into the torque acting on the rotation axis of a turbine is limited by the Betz law, which states that up to 16/27 (approximately 60%) of the kinetic energy can be transformed into rotational energy. State-of-the-art wind turbines are more than 90% effective, coming close to this theoretical optimum. So, is there any chance of extracting more energy from a flow tube within a given diameter?
Invention
The RES Ring Wing Turbine extracts energy from the flow using a circular rotor blade that forms a pressurised ring stabilised by tensioned spokes. The Ring Wing Turbine benefits from the radial expansion of the flow tube, which is induced by the radial spokes of the wheels acting as radial rotor blades. These blades transform the flow's kinetic energy into rotational energy by decreasing its speed and increasing the pressure within the flow tube, thus causing it to expand. At the outer ring-shaped rotor blade, a conical inflow angle causes rotation. Shaped like an airfoil, the suction side of the circular wing is on the outside of the wheel, causing an accelerated flow speed even at a distance from the surface of the wing. Therefore, the aerodynamic effective diameter of the RES Ring Wing Turbine is larger than its structural diameter, meaning that more energy can be converted than with a conventional wind turbine.
Advantages
- A simple and sturdy turbine design
- Applicable to turbines of all sizes
- Pressure and tension forces are separated
- Passive drive regulation by stall
- Full power output at a comparatively low tip speed ratio of 2.5–3.5
- Silent and imperceptible operation
Applications
- Wind and water turbines of different sizeS
- Validity of the structural principle for giant offshore wind turbines
- Wind turbines with a nominal capacity of 50 MW