scholarly journals Performance Optimization of Wind Turbine Rotors with Active Flow Control (Part 2)

2012 ◽  
Vol 134 (08) ◽  
pp. 55-55 ◽  
Author(s):  
G. Pechlivanoglou ◽  
C.N. Nayeri ◽  
C.O. Paschereit
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Performance Optimization ◽  
System Integration ◽  
Large Scale ◽  
Active Flow Control ◽  
Lightning Strike ◽  
Scale Production ◽  
Turbine Rotors ◽  
Active Flow

This article discusses the performance optimization of wind turbine rotors with active flow control. An extensive multi-parameter investigation with a thorough matrix-grading system was performed to identify the most suitable solution for industrial quality, short/mid-term implementation on actual utility scale wind turbines. A very wide selection of aerodynamic flow control solutions was analyzed based on extensive multi-disciplinary literature review and through aerodynamic and aeroelastic simulations. It is suggested that the trailing edge devices have the most favorable performance in the field of system integration and mechanical design performance. Compliant structures like the flexible flap keep the number of moving parts to a minimum while maintaining high performance and manufacturing simplicity. The use of flexible and elastic materials based on polymers or rubber material improves the lightning strike resistance of these solutions and allows for low-cost large-scale production. The actuator principle, sensitivity, and reliability are decisive parameters, and pneumatic actuators seem to strike a good balance between performance, cost, and reliability.

scholarly journals Performance Optimization of Wind Turbine Rotors with Active Flow Control (Part 1)

2012 ◽  
Vol 134 (04) ◽  
pp. 51-51 ◽  
Author(s):  
G. Pechlivanoglou ◽  
C.N. Nayeri ◽  
C.O. Paschereit
Keyword(s):  
Neural Network ◽  
Flow Control ◽  
Wind Turbine ◽  
Performance Optimization ◽  
Active Flow Control ◽  
Fine Tuning ◽  
Dynamic Force ◽  
Empirical Parameter ◽  
Turbine Rotors ◽  
Active Flow

This article describes the performance optimization of wind turbine rotors with active flow control. The active Gurney flap concept was tested in the wind tunnel under dynamic AoA variations to simulate unsteady inflow conditions. A high-deflection micro flap was actuated by four digital electric servos with a maximum deflection rate of 360°/sec. A custom code was created to allow dynamic AoA variations of the test wing with simultaneous dynamic force measurements. During the dynamic investigations, various control strategies were tested, starting from standard PID controllers with semi-empirical parameter tuning models to Direct Inverse Controllers with neural network tuning strategies and pure self-learning neural network controllers. The results of the closed-loop measurements using the manually tuned PID controller showed a reduction potential for the dynamic lift loads in the range of 70% as well as a stable controller behavior. The Direct Inverse Controller not only showed a load reduction of 36.8%, but also significant improvement potential with respect to its fine-tuning.

Performance Optimization of Wind Turbine Rotors With Active Flow Control

2011 ◽  
Author(s):  
G. Pechlivanoglou ◽  
C. N. Nayeri ◽  
C. O. Paschereit
Keyword(s):  
Steady State ◽  
Wind Tunnel ◽  
Flow Control ◽  
Wind Turbine ◽  
Performance Optimization ◽  
Active Flow Control ◽  
Performance Criteria ◽  
Extensive Literature ◽  
Turbine Rotors ◽  
Active Flow

This paper presents a series of investigations performed at the Hermann Fo¨ttinger Institute of TU Berlin. The initial scope of the investigations was the identification of Active Flow Control (AFC) solutions with significant implementation potential on wind turbine rotors. Several Active Flow Control solutions were thoroughly investigated based on extensive literature research. The performance of all the investigated solutions was ranked according to objective performance criteria and then the best performing solutions were selected for further numerical and experimental investigation. The selected Active Flow Control solutions were experimentally investigated with steady state wind tunnel measurements as well as steady state CFD simulations. The results of these investigations and the potential of each AFC solution are presented and discussed. The steady state tests were followed by a dynamic wind tunnel test campaign where the performance of one AFC solution (active Gurney flap) on a pitching test wing was investigated. The results of the static and dynamic investigations were very positive and proved the large load reduction potential of AFC on wind turbines.

Performance Optimization of Wind Turbine Rotors With Active Flow Control: Part 2—Active Aeroelastic Simulations

2012 ◽  
Author(s):  
G. Weinzierl ◽  
G. Pechlivanoglou ◽  
C. N. Nayeri ◽  
C. O. Paschereit
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Performance Optimization ◽  
Active Flow Control ◽  
Turbine Blades ◽  
Research Work ◽  
Optimal Solution ◽  
Simulation Code ◽  
Active Flow

This paper presents the continuation of the research efforts of the authors in the direction of the development of “smart blades” for the wind turbines of the future. Results from previous research work is further in combination with a newly developed simulation code in order to assess the performance of Active Flow Control (AFC) elements implemented on modern wind turbine blade structures. Parametric investigations have been conducted in order to identify the optimal configuration of various AFC elements. These are tested under identical boundary conditions to define an overall optimal solution. The results of the research project show that the Active Gurney Flap is the element with a highest probability for the fastest implementation on wind turbine blades for load alleviation purposes. The most promising however overall solution is the Flexible Trailing Edge Flap. With its high control authority and relatively high regulation speed is able to significantly vary the aerodynamic performance of wind turbines.

High Efficiency Wind Turbine Using Co-Flow Jet Active Flow Control

2021 ◽  
Author(s):  
Kewei Xu ◽  
Gecheng Zha
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Flow Separation ◽  
Power Output ◽  
Pitch Angle ◽  
Active Flow Control ◽  
Horizontal Axis Wind Turbine ◽  
Negative Power ◽  
Freestream Velocity ◽  
Active Flow

Abstract This paper applies Co-flow Jet (CFJ) active flow control airfoil to a NREL horizontal axis wind turbine for power output improvement. CFJ is a zero-net-mass-flux active flow control method that dramatically increases airfoil lift coefficient and suppresses flow separation at a low energy expenditure. The 3D Reynolds Averaged Navier-Stokes (RANS) equations with one-equation Spalart-Allmaras (SA) turbulence model are solved to simulate the 3D flows of the wind turbines. The baseline wind turbine is the NREL 10.06m diameter phase VI wind turbine and is modified to a CFJ blade by implementing CFJ along the span. The baseline wind turbine performance is validated with the experiment at three wind speeds, 7m/s, 15m/s, and 25m/s. The predicted blade surface pressure distributions and power output agree well with the experimental measurements. The study indicates that the CFJ can enhance the power output at the condition where angle of attack is increased to the level that conventional wind turbine is stalled. At the speed of 7m/s that the NREL turbine is designed to achieve the optimum efficiency at the pitch angle of 3°, the CFJ turbine does not increase the power output. When the pitch angle is reduced by 13° to −10°, the baseline wind turbine is stalled and generates negative power output at 7m/s. But the CFJ wind turbine increases the power output by 12.3% assuming CFJ fan efficiency of 80% at the same wind speed. This is an effective method to extract more power from the wind at all speeds. It is particularly useful at low speeds to decrease cut-in speed and increase power output without exceeding the structure limit. At the freestream velocity of 15m/s and the CFJ momentum coefficient Cμ of 0.23, the net power output is increased by 207.7% assuming the CFJ fan efficiency of 80%, compared to the baseline wind turbine due to the removal of flow separation. The CFJ wind turbine appears to open a door to a new area of wind turbine efficiency improvement and adaptive control for optimal loading.

Impact of the Precessing Vortex Core on NOx Emissions in Premixed Swirl-Stabilized Flames: An Experimental Study

2020 ◽  
Author(s):  
Finn Lückoff ◽  
Moritz Sieber ◽  
Christian Oliver Paschereit ◽  
Kilian Oberleithner
Keyword(s):  
Flow Control ◽  
Large Scale ◽  
Active Flow Control ◽  
Premixed Flame ◽  
Nox Emissions ◽  
Precessing Vortex Core ◽  
Flame Dynamics ◽  
Swirl Flows ◽  
Active Flow ◽  
The Impact

Abstract The reduction of polluting NOx emission remains a driving factor in the design process of swirl-stabilized combustion systems, to meet strict legislative restrictions. In reacting swirl flows, hydrodynamic coherent structures, such as periodic large-scale vortices in the shear layer, induce zones with increased heat release rate fluctuations in connection with temperature peaks, which lead to an increase of NOx emissions. Such large-scale vortices can be induced by the helical coherent structure known as precessing vortex core (PVC), which influences the flow and flame dynamics of reacting swirl flows under certain operating conditions. We developed an active flow control system, which allows for a targeted actuation of the PVC, to investigate its impact on important combustion properties. In this study, the direct active flow control is used to actuate a PVC of arbitrary frequency and amplitude, which facilitates a systematic study of the impact of the PVC on NOx emissions. In the course of the present work, a perfectly premixed flame, which slightly damps the PVC, is studied in detail. Since the PVC is slightly damped, it can be precisely excited by means of open-loop flow control. In connection with time-resolved OH*-chemiluminescence and stereoscopic PIV measurements, the flame and flow response to PVC actuation as well as the impact of the actuated PVC on flow and flame dynamics are characterized. It turns out that the PVC rolls up the inner shear layer, which results in an interaction of PVC-induced vortices and flame. This interaction considerably influences the measured level of NOx emissions, which grow with increasing PVC amplitude in a perfectly premixed flame. Nearly the same increase is to be seen for a partially premixed flame. This in contrast to previous studies, where the PVC is assumed to reduce the NOx emissions due to vortex-enhanced mixing.

Active flow control using pulsed micro-jets on a full-scale production car

2014 ◽  
Vol 6 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Jean-Luc Aider ◽  
Pierric Joseph ◽  
Tony Ruiz ◽  
Philippe Gilotte ◽  
Yoann Eulalie ◽  
...  
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Full Scale ◽  
Scale Production ◽  
Active Flow

Numerical investigation of active flow control with co-flowing jet in a horizontal axis wind turbine

2020 ◽  
pp. 0309524X2096139
Author(s):  
Fangrui Shi ◽  
Yingqiao Xu ◽  
Xiaojing Sun
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Performance Enhancement ◽  
Active Flow Control ◽  
Three Dimensional ◽  
Horizontal Axis ◽  
Suction Surface ◽  
Horizontal Axis Wind Turbine ◽  
Momentum Coefficient ◽  
Active Flow

In this paper, a three-dimensional numerical simulation of the aerodynamic performance of a horizontal axis wind turbine (HAWT) whose blades are equipped with a new active flow control concept called Co-Flowing Jet (CFJ) is carried out. Numerical results show that the use of CFJ over the blade suction surface can effectively delay flow separation, thus improving the net torque and power output of HAWT. Besides, this increment in the net power produced by the turbine is considerably higher than the power consumed by the CFJ. Thus, the overall efficiency of the HAWT can be greatly increased. Furthermore, influences of different CFJ operating parameters including location of injection port, jet momentum coefficient and slot length on the performance enhancement of a HAWT are also systematically studied and the optimal combination of these parameters to obtain the best possible turbine efficiency throughout a range of different wind speeds has been identified.

Design of a Large Scale Vertical Stabilizer Wind Tunnel Model for Active Flow Control Research

2012 ◽  
Author(s):  
Glenn Saunders ◽  
Edward Whalen ◽  
Helen Mooney ◽  
Sarah Zaremski
Keyword(s):  
Wind Tunnel ◽  
Flow Control ◽  
Large Scale ◽  
Active Flow Control ◽  
Scale Model ◽  
Tunnel Model ◽  
Control Research ◽  
Model Geometry ◽  
Design Requirements ◽  
Active Flow

The design, fabrication and installation of an approximately 1/6 scale model of an aircraft vertical stabilizer for research in Active Flow Control (AFC) is discussed. Highlighted are the unique design requirements of wind tunnel models, the specialized fabrication techniques employed to create them and the required close collaboration between industry, government and three academic institutions. The design of the model involves often competing constraints imposed by structural, instrumentation, aerodynamic, manufacturability and research-agenda considerations as well as cost and schedule. Instrumentation requires hundreds of pressure ports and six-axis force/torque sensing. Aerodynamic considerations necessitate high manufacturing precision, highly-skilled fabrication techniques and careful observance of model geometry throughout the design and fabrication processes. A scale model of a vertical stabilizer for AFC research was successfully designed, fabricated and deployed. The collaboratively designed model satisfies the structural, aerodynamic and research design constraints, and furthers the state of the art in Active Flow Control research.

Trailing edge noise reduction of wind turbine blades by active flow control

Wind Energy ◽  
2014 ◽  
Vol 18 (5) ◽  
pp. 909-923 ◽  
Author(s):  
Alexander Wolf ◽  
Thorsten Lutz ◽  
Werner Würz ◽  
Ewald Krämer ◽  
Oksana Stalnov ◽  
...  
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Noise Reduction ◽  
Active Flow Control ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Trailing Edge Noise ◽  
Active Flow
Sign in / Sign up

Export Citation Format

Share Document