Wind tunnel testing of a two-dimensional aerofoil with a load reducing flap has been conducted under the influence of a closed-loop controller (PID). Upstream synthetic perturbations for well-defined testing of the controller were generated by instrumenting the wind tunnel with two fast turning vanes placed in front of the main test wing. These were situated symmetrically above and below the airfoil in a way that created a fast turning of the air flow without directly affecting the boundary layer on the test airfoil. The Reynolds number was Re=500.000. The PID-controlled flap was able to alleviate the load variations with reductions above 80% for reduced frequencies up to k = 0.028 and nearly 70% at k=0.054. At about 0.108 and higher a different strategy is needed for the present setup as the reduction is low or even negative.
Proceedings of Torque 2012, the Science of Making Torque From Wind, 2012
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The science of Making Torque from Wind 2012European Academy of Wind Energy : The Science of Making Torque from Wind