Technology

Each blade consists of a set of two smaller blades. The theory behind the concept is, that two smaller blades running parallel utilizes the power in the wind better. At the same time, the joint 2/3 out from root of the blade makes it more stable and in larger scale weight can be reduced.

The concept is theoretically defined, and the performance is calculated based on aerodynamic models. Small blade models in wind tunnels have been tested and both the theoretical calculations and results from model tests show the improved performance.

The blade can be designed for stall- as well as pitch-regulated turbines. The first full size rotor set is produced for a pitch-regulated turbine and is produced in a length of 8 meter. A size which fits to 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

First design is planned to be implemented on a 60kW turbine. Based on a turbine like that, the performance specifications 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 gives this result:

Power curve. Conventional vs. JBRx16-60

The improvement of production is rather 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%