scholarly journals Computational characterization of a Gurney flap on a DU91(2)W250 airfoil

2020 ◽  
Vol 307 ◽  
pp. 01053
Author(s):  
Unai Fernandez-Gamiz ◽  
Iñigo Errasti ◽  
Ekaitz Zulueta ◽  
José Manuel Lopez Guede ◽  
Ana Boyano
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Turbine Rotor ◽  
Control Device ◽  
Airfoil Surface ◽  
Flow Control Devices ◽  
Cost Of Energy ◽  
Flow Control Device ◽  
Gurney Flap ◽  
The Cost

The considerable increase of wind turbine rotor size and weight in the last years has made impossible to control as they were controlled 20 years ago. The cost of energy is an essential role to maintain this type of energy as a viable alternative in economic terms with traditional or other renewable energies. Through the last decades many different flow control devices have been developed. Most of them were shaped for aeronautical issues and this was its first research application. Currently researchers are working to optimize and introduce these types of devices in multi megawatt wind turbines. Gurney flap (GF) is a vane perpendicular to the airfoil surface with a size between 0.1 and 3% of the airfoil chord length, placed in the lower or upper side of the airfoil close to the trailing edge of the airfoil. When GFs are appropriately designed, they increase the total lift of the airfoil while reducing the drag. Thanks to the implementation of the of this flow control device the efficiency of a wind turbine improves, which results on an increase in the power generation.

Wind-Turbine Vibration Reduction Using Flow Control Devices

2017 ◽  
Author(s):  
Ho-Young Kim ◽  
Jae-Hung Han
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Vibration Reduction ◽  
Plasma Actuator ◽  
Control Device ◽  
Wind Turbine Blades ◽  
Flow Control Devices ◽  
Flow Control Device

The size of wind turbine blades has been continuously increased for better aerodynamic efficiency. However, the large scale blades induce loud noise and vibration as well as the increased difficulty in maintenance; all of these eventually causes the increase in the cost of energy. The vibration of wind turbines is mainly caused by wind turbulence, wind shear, and tower shadow. These causes change in local angle of attack of wind turbine blades and create mostly periodic vibration. In this work, a flow control device is applied for vibration reduction of wind turbine blades. The conventional role of flow control devices is to increase lift coefficient and to reduce drag coefficient by flow separation delay. In this research, flow control device is used to make a flat slope of lift coefficient in specific angle of attack range for vibration reduction; lift coefficient is not always increased but also decreased, too. To manipulate the lift coefficient slope, several types of flow separation controller are considered. Finally, a plasma actuator is selected because the minimal structural modification is necessary while providing sufficient lift coefficient control. The plasma actuator is attached to an airfoil to blow the jet upwind to decrease the lift. Computational fluid dynamics simulation is conducted to estimate the flow control performance of the plasma actuator. Experiments are conducted on a DU35-A17 airfoil to verify the lift coefficient manipulation performance of the plasma actuator.

scholarly journals Comparison between upwind and downwind designs of a 10 MW wind turbine rotor

2018 ◽  
Author(s):  
Pietro Bortolotti ◽  
Abinhav Kapila ◽  
Carlo L. Bottasso
Keyword(s):  
Wind Turbine ◽  
Energy Production ◽  
Turbine Rotor ◽  
Design Tool ◽  
Operating Conditions ◽  
Cost Of Energy ◽  
Potential Benefits ◽  
The Cost ◽  
Interesting Alternative ◽  
Wind Turbine Rotor

Abstract. The size of wind turbines has been steadily growing in the pursuit of a lower cost of energy by an increased wind capture. In this trend, the vast majority of wind turbine rotors has been designed based on the conventional three-bladed upwind concept. This paper aims at assessing the optimality of this configuration with respect to a three-bladed downwind design, with and without an actively controlled variable coning used to reduce the cantilever loading of the blades. A 10 MW wind turbine is used for the comparison of the various design solutions, which are obtained by an automated comprehensive aerostructural design tool. Results show that, for this turbine size, downwind rotors lead to blade mass and cost reductions of 6 % and 2 %, respectively, compared to equivalent upwind configurations. Due to a more favorable rotor attitude, the annual energy production of downwind rotors may also slightly increase in complex terrain conditions characterized by a wind upflow, leading to an overall reduction in the cost of energy. However, in more standard operating conditions, upwind rotors return the lowest cost of energy. Finally, active coning is effective in alleviating loads by reducing both blade mass and cost, but these potential benefits are negated by an increased system complexity and reduced energy production. In summary, a conventional design appears difficult to beat even at these turbine sizes, although a downwind non-aligned configuration might result in an interesting alternative.

scholarly journals Review of Flow‐Control Devices for Wind‐Turbine Performance Enhancement

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1268
Author(s):  
Md. Zishan Akhter ◽  
Farag Khalifa Omar
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Performance Enhancement ◽  
Turbine Blades ◽  
Control Mechanisms ◽  
Power Sources ◽  
Turbine Performance ◽  
Flow Control Devices ◽  
Cost Of Energy ◽  
Control Devices

It is projected that, in the following years, the wind‐energy industry will maintain its rapid growth over the last few decades. Such growth in the industry has been accompanied by the desirability and demand for larger wind turbines aimed at harnessing more power. However, the fact that massive turbine blades inherently experience increased fatigue and ultimate loads is no secret, which compromise their structural lifecycle. Accordingly, this demands higher overhaul‐and‐maintenance (O&M) costs, leading to higher cost of energy (COE). Introduction of flow‐control devices on the wind turbine is a plausible solution to this issue. Flow‐control mechanisms feature the ability to effectively enhance/suppress turbulence, advance/delay flow transition, and prevent/promote separation, leading to enhancement in aerodynamic and aeroacoustics performance, load alleviation and fluctuation suppression, and eventually wind turbine power augmentation. These flow‐control devices are operated primarily under two schemes: passive and active control. Development and optimization of flow‐control devices present the potential for reduction in the COE, which is a major challenge against traditional power sources. This review performs a comprehensive and up‐to‐date literature survey of selected flow‐control devices, from their time of development up to the present. It contains a discussion on the current prospects and challenges faced by these devices, along with a comparative analysis centered on their aerodynamic controllability. General considerations and conclusive remarks are presented after the discussion.

scholarly journals CNN-Based Flow Control Device Modelling On Aerodynamic Airfoils

2021 ◽  
Author(s):  
Koldo Portal-Porras ◽  
Unai Fernandez-Gamiz ◽  
Ekaitz Zulueta ◽  
Alejandro Ballesteros-Coll ◽  
Asier Zulueta
Keyword(s):  
Flow Control ◽  
Flow Characteristics ◽  
Control Device ◽  
Computational Time ◽  
Cfd Simulations ◽  
Turbine Performance ◽  
Flow Control Devices ◽  
Flow Control Device ◽  
Computational Fluid Dynamics Cfd ◽  
Control Devices

Abstract Wind energy has become an important source of electricity generation, with the aim of achieving a cleaner and more sustainable energy model. However, wind turbine performance improvement is required to compete with conventional energy resources. To achieve this improvement, flow control devices are implemented on airfoils. Computational Fluid Dynamics (CFD) simulations are the most popular method for analyzing this kind of devices, but in recent years, with the growth of Artificial Intelligence, predicting flow characteristics using neural networks is becoming increasingly popular. In this work, 158 different CFD simulations of a DU91W(2)250 airfoil are conducted, with two different flow control devices, rotating microtabs and Gurney flaps, added on its Trailing Edge (TE). These flow control devices are implemented by using the cell-set meshing technique. These simulations are used to train and test a Convolutional Neural Network (CNN) for velocity and pressure field prediction and another CNN for aerodynamic coefficient prediction. The results show that the proposed CNN for field prediction is able to accurately predict the main characteristics of the flow around the flow control device, showing very slight errors. Regarding the aerodynamic coefficients, the proposed CNN is also capable to predict them reliably, being able to properly predict both the trend and the values. In comparison with CFD simulations, the use of the CNNs reduces the computational time in four orders of magnitude.

scholarly journals Optimal Wind Turbine Operation by Artificial Neural Network-Based Active Gurney Flap Flow Control

2019 ◽  
Vol 11 (10) ◽  
pp. 2809 ◽  
Author(s):  
Aitor Saenz-Aguirre ◽  
Unai Fernandez-Gamiz ◽  
Ekaitz Zulueta ◽  
Alain Ulazia ◽  
Jon Martinez-Rico
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Flow Control ◽  
Wind Turbine ◽  
Lift Force ◽  
Energy Output ◽  
Flow Control Devices ◽  
Gurney Flap ◽  
Control Devices ◽  
Artificial Neural

Flow control devices have been introduced in the wind energy sector to improve the aerodynamic behavior of the wind turbine blades (WTBs). Among these flow control devices, Gurney flaps (GFs) have been the focus of innovative research, due to their good characteristics which enhance the lift force that causes the rotation of the wind turbine rotor. The lift force increment introduced by GFs depends on the physical characteristics of the device and the angle of attack (AoA) of the incoming wind. Hence, despite a careful and detailed design, the real performance of the GFs is conditioned by an external factor, the wind. In this paper, an active operation of GFs is proposed in order to optimize their performance. The objective of the active Gurney flap (AGF) flow control technique is to enhance the aerodynamic adaption capability of the wind turbine and, thus, achieve an optimal operation in response to fast variations in the incoming wind. In order to facilitate the management of the information used by the AGF strategy, the aerodynamic data calculated by computational fluid dynamics (CFD) are stored in an artificial neural network (ANN). Blade element momentum (BEM) based calculations have been performed to analyze the aerodynamic behavior of the WTBs with the proposed AGF strategy and calculate the corresponding operation of the wind turbine. Real wind speed values from a meteorological station in Salt Lake City, Utah, USA, have been used for the steady BEM calculations. The obtained results show a considerable improvement in the performance of the wind turbine, in the form of an enhanced generated energy output value and a reduced bending moment at the root of the WTB.

The Development of Active Flow Control Devices From Shape Memory Alloys for the Convective Cooling of Heated Surfaces

2008 ◽  
Author(s):  
Mohd S. Aris ◽  
Ieuan Owen ◽  
Chris J. Sutcliffe
Keyword(s):  
Heat Transfer ◽  
Flow Control ◽  
Heated Surface ◽  
Active Flow Control ◽  
Control Device ◽  
Flow Control Devices ◽  
Flow Control Device ◽  
Control Devices ◽  
Channel Configuration ◽  
Active Flow

This paper is concerned with the convective heat transfer of heated surfaces through the use of active flow control devices. An investigation has been carried out into the use of two flow control design configurations manufactured from Shape Memory Alloys (SMAs) which are activated at specified temperatures. In this design, a high surface temperature would activate rectangular flaps to change shape and protrude at a 45° angle of attack. This protrusion would generate longitudinal vortices and at the same time allow air to flow into cooling channels underneath the flaps, cooling a heated surface downstream of the flow control device. One- and two-channel flow control configurations were explored in this work. The flow control device was made from pre-alloyed powders of SMA material in a rapid prototyping process known as Selective Laser Melting (SLM). It was tested for its heat transfer enhancement in an open test section wind tunnel supplied with low velocity air flow. Infrared thermography was used to evaluate the surface temperatures of the downstream heated surface. Promising results were obtained for the flow control design when the heated surface temperatures were varied from 20 °C to 85 °C. In the one-channel configuration, the flow control device in its activated shape increased heat transfer to a maximum of 50% compared to its deactivated shape. The activated flow control device in the two-channel configuration experienced a heat transfer enhancement of up to 90% compared to when it is deactivated.

Optimizing of Flow Control Devices in a Single Strand Continuous Casting Tundish

2011 ◽  
Vol 284-286 ◽  
pp. 1209-1215 ◽  
Author(s):  
Lei Lei Zhang ◽  
Deng Fu Chen ◽  
Qiang Liu ◽  
Min Zhang ◽  
Xin Xie ◽  
...  
Keyword(s):  
Flow Field ◽  
Continuous Casting ◽  
Flow Control ◽  
Control Device ◽  
Flow Control Devices ◽  
Flow Control Device ◽  
Continuous Casting Tundish ◽  
Control Devices ◽  
Water Simulation ◽  
Orthogonal Optimization

Flow control devices (weir and dam) in a continuous casting tundish are very important to the flow field, which influences the temperature uniform and the inclusion floating. In this work, the weir and dam were firstly optimized through numerical simulation and water simulation synthetically by orthogonal optimization tests. And the optimal parameters showed that the distance from upper weir to inlet was 1000 mm, the distance of upper weir to tundish bottom was 150 mm, the distance from upper weir to dam was 600 mm, and the height of the dam was 320 mm. Then the effect of different arrangement holes on the dam was discussed through RTD curve and velocity field under the optimum flow control device. And it revealed that the hole influenced the flow pattern in that area obviously, a dam with two holes could get a better flow field.

Sound suppressing gas flow control device

1980 ◽  
Vol 67 (4) ◽  
pp. 1413-1413
Author(s):  
George J. Kay ◽  
Alan Keskimen
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Control Device ◽  
Flow Control Device
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