Each blade consists of a set of two smaller blades. The theory behind this concept is that the two smaller blades running parallel will utilize the power in the wind better. At the same time, the joint is placed two-thirds of the way out from the root of the blade making it more stable, and at a larger scale, the weight can be reduced.
The concept is theoretically defined, and the performance is calculated based on aerodynamic models. Small blade models have been tested in wind tunnels, and both the theoretical calculations and results from model tests show the improved performance.
The blade can be designed to stall just like pitch regulated turbines. The first full size rotor set is produced for a pitch regulated turbine and is produced at a length of 8 meters which fits a 60KW turbine.
The blade is produced in standard glass fiber, and as the sketch shows, a root connector attaches the ends of the two blades to a standard root mounting. This way the blade can be mounted on any pitch regulated turbine and is not dependent upon a specific root connection.
Specifications
The first design is planned to be implemented on a 60kW turbine. Based on this type of turbine, the performance specifications are expected to look like this:
Specifications of JBRx16-60:
| Rated power | 60 kW | |
| Rotor diameter | 16 m | |
| Sweep area | 200 sq.m | |
| Power regulation | Active pitch | |
| Number of joined blades | 3 | |
| RPM | 56 | |
| Wind class | II | |
| Relevant standard | IEC 61400-2 | |
| Cp Value | 0,543 |
Summarizing these specifications in a power curve model, the results will look like this:
Power curve. Conventional vs. JBRx16-60
The improvement of energy production is extensive. I.e. is the average energy production (AEP) assuming 6 m/s and a 60kW turbine improved with 18,5%.
| Class | IV | III | II | I | ||
| Mean wind speed, m/s | 6 | 7,5 | 8,5 | 10 | ||
| AEP improvement | 18,5% | 13,2% | 10,7% | 8,0% |