Chaired by: J. Sørensen, S. Ivanell
09:00
Experimental Study on the Effects of Winglets on the Performance of Two Interacting Horizontal Axis Model Wind Turbines
Yasar Ostovan | METUWIND | Turkey
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Authors:
Yasar Ostovan | METUWIND | Turkey
Oguz Uzol | Turkey
The focus of this experimental study is to investigate the effects of winglets on the performance of two interacting similar horizontal axis model wind turbines. For this purpose, a downwind winglet is designed and manufactured to be attached to the blade tips of the upstream turbine. A set of wing extensions with the same length as the winglets is also produced to be compared to the winglets. Power and thrust coefficients of both turbines are measured with winglets as well as with wing extensions attached to the blade tips of the upstream turbine and are compared to the baseline case (rectangular tip without any tip devices). The model turbines are three bladed and have a rotor diameter of 0.94 m. The measurements are performed in two different wind tunnels (closed test section and open jet). For both sets of measurements, winglets have a noticeable increasing effect on the power coefficient of the individual turbine. There is an increase in the thrust coefficient as well.
09:20
An investigation of unsteady 3D effects on trailing edge flaps
Eva Jost | Universität Stuttgart | Germany
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Authors:
Eva Jost | Universität Stuttgart | Germany
Annette Fischer | Germany
Thorsten Lutz | Germany
Ewald Krämer | Germany
The present study investigates the impact of unsteady and viscous three-dimensional aerodynamic effects on a wind turbine blade with trailing edge flap by means of CFD. Harmonic oscillations are simulated on the DTU 10 MW rotor with a flap of 10% chord extent ranging from 70% to 80% blade radius. The deflection frequency is varied in the range between 1p and 6p. To quantify 3D effects, rotor simulations are compared to 2D airfoil computations. A significant influence of trailing and shed vortex structures has been found which leads to a reduction of the lift amplitude and hysteresis effects in the lift response with regard to the flap deflection. In the 3D rotor results greater amplitude reductions and less hystereses have been found compared to the 2D airfoil simulations.
09:40
Full scale wind turbine test of vortex generators mounted on the entire blade
Christian Bak | DTU | Denmark
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Authors:
Christian Bak | DTU | Denmark
Witold Skrzypinski | Denmark
Mac Gaunaa | Denmark
Hector Villanueva | Denmark
Niels Brønnum | Denmark
Emil Olsen | Denmark
Measurements on a heavily instrumented pitch regulated variable speed Vestas V52 850 kW wind turbine situated at the DTU Risoe¸ Campus are carried out, where the effect of vortex generators mounted on almost the entire blade is tested with and without leading edge roughness. The measurements are compared to the predictions carried out by a developed design tool, where the effect of vortex generators and leading edge roughness is simulated using engineering models. The measurements will validate the design tool and document how the vortex generators will influence the power and the loads.
10:00
Experimental Measurement and CFD Model Development of Thick Wind Turbine Airfoils with Leading Edge Erosion
Dr. David Maniaci | Sandia National Laboratories | United States
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Authors:
Dr. David Maniaci | Sandia National Laboratories | United States
Edward White | United States
Benjamin Wilcox | United States
Case van Dam | United States
Christopher Langel | United States
Joshua Paquette | United States
Leading edge erosion is an emerging issue in wind turbine blade reliability, causing performance decreases and additional maintenance costs. Through the U.S. DOE Blade Reliability Collaborative, researchers from Sandia National Laboratories, Texas A&M, and U.C. Davis have recently addressed the subject of performance loss. The surface roughness caused by blade leading edge erosion was characterized in the field and used to inform wind tunnel tests. Researchers then used the wind tunnel measurements to develop a predictive model of roughness-induced boundary layer transition for wind energy applications. A further analysis calculated the effects of erosion on wind turbine energy capture.
10:20
Comparison of flow modification induced by plasma and fluidic jet actuators dedicated to circulation control around wind turbine airfoils
Dr. Annie Leroy | University of Orleans | France
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Authors:
Dr. Annie Leroy | University of Orleans | France
Caroline Braud | France
Sophie Baleriola | France
Stéphane Loyer | France
Philippe Devinant | France
Sandrine Aubrun | France
In order to reduce the aerodynamic load fluctuations on wind turbine blades by innovative control solutions, strategies of active circulation control acting at the blade airfoil trailing edge are studied, allowing lift increase and decrease. This study presents a comparison of results obtained by performing surface plasma and continuous fluidic jet actuation on a blade airfoil designed with a rounded trailing edge. In the present study, both actuator types are located at the trailing edge. Plasma actuators act uniformly in the spanwise direction, whereas fluidic jets blow through small squared holes distributed along the span, and therefore, provide a three-dimensional action on the flow. Load and velocity field measurements were performed to assess the effectiveness of both actuators and to highlight the flow mechanisms induced by both actuation methods for lift-up configurations.
10:40
CFD simulation of a 2 bladed multi megawatt wind turbine with flexible rotor connection
Levin Klein | Universität Stuttgart | Germany
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Authors:
Levin Klein | Universität Stuttgart | Germany
Birger Luhmann | Germany
Karl-Naik Rösch | Germany
Thorsten Lutz | Germany
Po-Wen Cheng | Germany
Ewald Krämer | Germany
An innovative passive load reduction concept for a two bladed 3.4 MW wind turbine is investigated by a conjoint CFD and MBS - BEM methodology. The concept consists of a flexible hub mount which allows a tumbling motion of the rotor. First, the system is simulated with a MBS tool coupled to a BEM code. Then, the resulting motion of the rotor is extracted from the simulation and applied on the CFD simulation as prescribed motion. The aerodynamic results show a significant load reduction on the support structure. Hub pitching and yawing moment amplitudes are reduced by more than 50% in a vertically sheared inflow. Furthermore, the suitability of the MBS-BEM approach for the simulation of the load reduction system is shown.