In the previous Joule II programme (JOU2-CT93-0411) it was demonstrated that air jet vortex generators (ajvg's) could be used to actively modify the blade characteristics (lift & drag) of a fixed pitch wind turbine. Hence, it was shown that the power of the machine could be regulated without having to use actuators to pitch the blades or by using complex variable speed electronics. To fully exploit air jet technology commercially, it is necessary, to understand the flow mechanics of ajvg's in flow that is of a highly 3 dimensional nature. It is therefore proposed that a CFD analysis of the problem is undertaken, so that ajvg's can be optimised for any fixed pitch wind turbine. With such a tool, full commercialisation of ajvg's may be achieved quickly, enabling higher energy yields than the original stall regulated machine (5-10%) with a level of power regulation equivalent to that of a pitch controlled machine.
To achieve this goal it is proposed that LM Glasfiber, Ecotecnia Scc Ltd., National Technical University of Athens and City University should form a partnership with the following technical objectives:
1. To model ajvg's numerically with CFD, allowing blade manufacturers to add ajvg's to any existing or future blade design, in order to increase energy capture.
2. To manufacture a 19.1 metre blade modified with ajvg's optimised by the CFD model, along with the necessary control system.
3. To test the modified blade at full scale and compare the results with the numerical predictions, which will also be validated experimentally in the wind tunnel.
4. To give guidelines on how an air jet control system should be designed and by what process ajvg's should be manufactured into the blade. 5. Additionally, the partnership will use the CFD tool to investigate how best to use ajvg's as the basis for blade design, rather than as an 'add on' to an existing design. E.g. use profiles that maximise the gains from ajvg's to make lighter blades.
The achievement of these objectives should result in the following industrial benefits.
. Power regulation of a fixed pitch turbine similar to that of a pitch controlled machine.
. Increased energy capture over the equivalent stall regulated turbine of the order 5-10% by the above stated emulation of a fixed pitch machine. . The benefits associated with stall regulated machines over other control types, namely reduced cost of manufacture.
Having completed the project, the CFD model of ajvg's would allow their immediate integration into existing blade designs in an optimum configuration.
Funding SchemeCSC - Cost-sharing contracts