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ECN publication
Dynamic inflow: yawed conditions and partial span pitch control
Published by: Publication date:
ECN 1995
ECN report number: Document type:
ECN-C--95-056 ECN publication
Number of pages: Full text:
237 Download PDF  

The objective of the project was to further validate the engineeringmodels, which have been developed in the JOULE 1 project: 'Joint Investigation of Dynamic Inflow Effects and Implementation of an Engineering Method'. These models were developed to describe the wake induced unsteadiness and non-uniformity in the rotor inflow, which occur at full span pitching variations, coherent wind gusts and yawed conditions. The further validation of these engineering models was based on full scale measurements on the Dutch WPS-30 turbine and the German Uniwex turbine, wind tunnel measurements and comparison of results with advanced free wake methods. By combining the JOULE 1 and JOULE 2 results, much insight was gained in dynamic inflow phenomena. In several measurement campaigns on turbines which were exposed to fast (full span) pitching transients or yawed conditions, dynamic inflow effects were clearly apparent in the mechanical loads and a general validation of the dynamic inflow models was possible. It was shown that dynamic inflow effects at pitching transients become more important with increasing size and pitching speed of the turbine. Dynamic inflow effects at yawed conditions become more significant with increasing loading and tip speed ratio. A second objective of the project was to extend the dynamic inflow engineering methods for partial span pitch conditions. The validation of these models was based on measurements on the Howden Richborough turbine and calculational results from the advanced free wake methods. It is found that dynamic inflow for partial span pitch control is less significant. As final conclusion it can be stated that the newly developed engineering methods predict the dynamic inflow effects well. This appeared to be true for a large range of rotor sizes and operational conditions. Therefore it is recommended to replace the steady equilibrium wake models in aeroelastic codes, by one of the engineering methods from the present projects. 64 figs., 11 tabs., 16 refs., 14 appendices

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