Objectif
To investigate possible modifications of blade tips to reduce acoustic noise and to improve rotor performance.
It is the aim of this project to reduce the noise produced by tip vortices, in analogy to the various methods in the field of commercial aircrafts and gliders with high aerodynamic performance to avoid induced drag and in the field of helicopters and propellers with very high tip speeds to avoid acoustic noise. According to this several different blade tips of a wind turbine with higher tip speed are to be investigated concerning their influence on noise and power output.
Free field measurement will be performed to assess the applicability of the different tip shapes. In order to minimize the cost of the research programme as wind turbine already installed at DLR-wind test site will be used.
It is proposed to operate the UNIWEX-wind turbine, a development of University of Stuttgart (ICA). This research machine is fully equipped for power, load and dynamic behaviour measurements. In addition it is possible to change geometric features i.e. cone angle, shaft inclination angle, upwind or downwind configuration, teetering/fixed hub. For fast and easy handling, the tower can be tilted by hydraulic devices. Both blades have removable tips.
The turbine is pitch controlled and can be operated as a variable or constant speed machine. For special tasks it is possible to run the rotor during calms, driven by a hydraulic motor. The relatively small size of the rotor of 16 m diameter and the easy handling on the ground will reduce costs significantly.
The free field measurements are planned to be carried out by DLR and ICA. The rotor data and the basic turbine data are delivered automatically to the data acquisition system of the test site.
The noise measurement equipment will be installed by ECN. A correlation between the recorded data and the noise measurements must be guaranteed. Those recorded data will be sent to ECN for further evaluation after each measurement campaign.
The other data will be recorded in two ways. Raw data measurement for each tip at each typical wind speed and the corresponding operation modes of the WEC must be recorded including the above-mentioned noise measurements. Those raw data should be measured during reproducible weather conditions e.g. only west wind, with the same turbulence and so on. The second part are long term measurements of wind and power output as one minute or ten minutes averages to find out the influence of the different tips w.r.t. the tip loss effect.
Champ scientifique
Thème(s)
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70569 STUTTGART
Allemagne