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Investigation of Laminar–Turbulent Transition on a Rotating Wind-Turbine Blade of Multimegawatt Class with Thermography and Microphone Array
- Source :
- Energies, Vol 12, Iss 11, p 2102 (2019), Energies; Volume 12; Issue 11; Pages: 2102
- Publication Year :
- 2019
- Publisher :
- MDPI AG, 2019.
-
Abstract
- Knowledge about laminar–turbulent transition on operating multi megawatt wind turbine (WT) blades needs sophisticated equipment like hot films or microphone arrays. Contrarily, thermographic pictures can easily be taken from the ground, and temperature differences indicate different states of the boundary layer. Accuracy, however, is still an open question, so that an aerodynamic glove, known from experimental research on airplanes, was used to classify the boundary-layer state of a 2 megawatt WT blade operating in the northern part of Schleswig-Holstein, Germany. State-of-the-art equipment for measuring static surface pressure was used for monitoring lift distribution. To distinguish the laminar and turbulent parts of the boundary layer (suction side only), 48 microphones were applied together with ground-based thermographic cameras from two teams. Additionally, an optical camera mounted on the hub was used to survey vibrations. During start-up (SU) (from 0 to 9 rpm), extended but irregularly shaped regions of a laminar-boundary layer were observed that had the same extension measured both with microphones and thermography. When an approximately constant rotor rotation (9 rpm corresponding to approximately 6 m/s wind speed) was achieved, flow transition was visible at the expected position of 40% chord length on the rotor blade, which was fouled with dense turbulent wedges, and an almost complete turbulent state on the glove was detected. In all observations, quantitative determination of flow-transition positions from thermography and microphones agreed well within their accuracy of less than 1%.
- Subjects :
- Microphone array
Control and Optimization
Materials science
Turbine blade
boundary-layer transition
wind turbine
thermography
aerodynamic glove
Microphone
Hochgeschwindigkeitskonfigurationen, GO
Acoustics
Energy Engineering and Power Technology
lcsh:Technology
01 natural sciences
Turbine
010305 fluids & plasmas
law.invention
010309 optics
law
0103 physical sciences
Laminar-turbulent transition
Electrical and Electronic Engineering
Engineering (miscellaneous)
lcsh:T
Renewable Energy, Sustainability and the Environment
Laminar flow
Boundary layer
Thermography
Energy (miscellaneous)
Subjects
Details
- ISSN :
- 19961073
- Volume :
- 12
- Database :
- OpenAIRE
- Journal :
- Energies
- Accession number :
- edsair.doi.dedup.....87c5ae0cb6032796532319d7e239921e
- Full Text :
- https://doi.org/10.3390/en12112102