Optimal Design of Wind Turbines Using BIAS, A Method of Multipliers Code

1988 ◽  
Author(s):  
B. D. Vick ◽  
W. Wrigglesworth ◽  
L. B. Scott ◽  
K. M. Ragsdell
Keyword(s):  
Optimal Design ◽  
Rough Surface ◽  
Wind Turbines ◽  
Lift Coefficient ◽  
Power Coefficient ◽  
Method Of Multipliers ◽  
High Lift ◽  
Small Wind Turbines ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract A method has been developed and is demonstrated which determines the chord and twist distribution for a wind turbine with maximum power coefficient. Only small wind turbines (less than 10 kilowatts) are considered in this study, but the method could be used for larger wind turbines. Glauert determined a method for estimating the chord and twist distribution that will maximize the power coefficient if there is no drag. However, the method proposed here determines the chord and twist distribution which will maximize the power coefficient with the effect of drag included. Including drag in the analysis does not significantly affect the Glauert chord and twist distribution for airfoils with a high lift coefficient at the maximum lift to drag ratio. However, if the airfoil has a fairly low lift coefficient at its maximum lift to drag ratio due to its shape or a rough surface then significant improvement can be obtained in power coefficient by altering the Glauert chord and twist distribution according to the method proposed herein.

Genetic Algorithm-Based Design of Airfoil for the Root Region of Small Wind Turbines and Performance Analysis With Gurney Flaps

2018 ◽  
Author(s):  
Mohammed Rafiuddin Ahmed ◽  
Krishnil R. Ram ◽  
Bum-Suk Kim ◽  
Sunil P. Lal
Keyword(s):  
Genetic Algorithm ◽  
Wind Turbines ◽  
Lift Coefficient ◽  
Lower Surface ◽  
Trailing Edge ◽  
Gurney Flaps ◽  
Root Region ◽  
Small Wind Turbines ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The root region of small wind turbines experience low Reynolds number (Re) flow that makes it difficult to design airfoils that provide good aerodynamic performance and at the same time, provide structural strength. In the present work, a multi-objective genetic algorithm code was used to design airfoils that are suitable for the root region of small wind turbines. A composite Bezier curve with two Bezier segments and 16 control points (11 of them controlled) was used to parametrize the airfoil problem. Geometric constraints including suitable curvature conditions were enforced to maintain the airfoil thickness between 18% and 22% of chord and a trailing edge thickness of 3% of chord. The objectives were to maximize the lift-to-drag ratio for both clean and soiled conditions. Optimization was done by coupling the flow solver to a genetic algorithm code written in C++, at Re = 200,000 and for angles of attack of 4 and 10 degrees, as the algorithm was found to give smooth variation of lift-to-drag ratio within such a range. The best airfoil from the results was tested in the wind tunnel as well as using ANSYS-CFX. The experimental airfoil had a chord length of 75 mm and was provided with 33 pressure taps. Testing was done for both free and forced transition cases. The airfoil gave the highest lift-to-drag ratio at an angle of 6 degrees with the ratio varying very little between 4 degrees and 8 degrees. Forced transition at 8% of chord did not show significant change in the performance indicating that the airfoil will perform well even in soiled condition. Fixed trailing edge flaps (Gurney flaps) were provided right at the trailing edge on the lower surface. The lift and drag behavior of the airfoil was then studied with Gurney Flaps of 2% and 3% heights, as it was found from previous studies that flap heights of 1% or greater than 3% do not give optimum results. The flaps considerably improved the suction on the upper surface and also improved the pressure on the lower surface, resulting in a higher lift coefficient; at the same time, there was also an increase in the drag coefficient but it was less compared to the increase in the lift coefficient. The results indicate that Gurney flaps can be effectively used to improve the performance of thick trailing edge airfoils designed for the root region of small wind turbines.

Development of a new aerofoil profile with a high lift-to-drag ratio for wind turbines using a low fidelity accurate optimization flow solver

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Moutaz Elgammi ◽  
Aljonid Aokaly ◽  
Yasser Aldali
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Operating Conditions ◽  
High Lift ◽  
Operational Conditions ◽  
2D Simulation ◽  
Free Environment ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract A significant amount of work is performed on various aerofoil profiles to improve their characteristics for wind turbine applications. The main purpose is to increase the power output of wind turbines by increasing the lift-to-drag ratio of the aerofoil blade sections. However, most of the developed aerofoil profiles work well only at their design angles of attack and for low Reynolds numbers with a very dramatic stall that could significantly influence the characteristics of the aerofoil profiles and the performance of wind turbines. The present paper is conducted to develop a new aerofoil profile with more gradual stall characteristics that works efficiently for different operational conditions (clean and rough working conditions) similar to those encountered by wind turbines in the free environment. The new aerofoil profile was developed based on a combination between experimental Box–Behnken design and XFOIL code, measurements, and 2D simulation conducted by computational fluid dynamics (CFD) method. The established aerofoil can be used for wind turbine blades because it gives high lift-to-drag-ratios with very smooth and gradual stall characteristics even under very rough operating conditions.

Effects of Aspect Ratio on the Hydrodynamic Performance of Circular Cambered Otter Board

2018 ◽  
Author(s):  
Liuyi Huang ◽  
Yuyan Li ◽  
Jiqiang Xu ◽  
Qingchang Xu ◽  
Fenfang Zhao ◽  
...  
Keyword(s):  
Lift Coefficient ◽  
Flow Distribution ◽  
Full Scale ◽  
Hydrodynamic Performance ◽  
High Lift ◽  
Aspect Ratios ◽  
Simulation Results ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Good Agreement

An otter board is an important device that provides a desired horizontal opening of a trawl net. A high lift coefficient or lift-to-drag ratio is required for an otter board to maintain fishing efficiency. In the present work, the hydrodynamic performance of a circular cambered otter board was studied by numerical simulation, including the effects of aspect ratios (AR), and flow distribution around the otter board. Model tests were conducted in the flume tank as well as a comparison to the numerical results. It showed that simulation results exhibited very good agreement with experiment results. Results demonstrated that the model otter board had a critical angle of attack (AOA) of 50° (when the stall appeared). The maximum lift coefficient and lift-to-drag ratio of the model otter board were 2.421 and 3.719, respectively. However, the maximum values of the full-scale otter board increased first and then decreased with an increasing AR. And the full-scale otter board had a better performance when AR = 2.489, it can enhance the lift coefficient by 17.4% compared with the initial otter board (AR = 1.25). In addition, the flow distribution around the otter board showed that the flow was smooth at small AOAs, when it attacked at large AOA (exceeded 55°), flow separation and eddies were appeared at the lee-side of the otter board.

An Investigation of Drag Reduction on Gurney Flaps by an Three-Element Airfoil

2011 ◽  
Vol 138-139 ◽  
pp. 229-233
Author(s):  
Pei Qing Liu ◽  
Shuo Yang ◽  
Yun Tian
Keyword(s):  
Drag Coefficient ◽  
Aerodynamic Characteristic ◽  
Lift Force ◽  
Lift Coefficient ◽  
Simulation Method ◽  
High Lift ◽  
Gurney Flap ◽  
Different Types ◽  
Drag Ratio ◽  
Lift To Drag Ratio

During airplane’s take-off, higher lift force should be provided by wing used high lift devices, and the drag should be lower. The design basis of high lift devices with good aerodynamic characteristic is the design of the multi-element airfoil. When a multi-element airfoil is used Gurney flap, lift coefficient can be improved while drag coefficient is also increased, but the lift-to-drag ratio is reduced. In this paper, the numerical simulation method is used to study the aerodynamic characteristic of the multi-element airfoil used Gurney flap with slat in the configuration of take-off. Lift coefficient and drag coefficient of the multi-element airfoil with Gurney flap can be reduced by slat while lift-to-drag ratio of airfoil is increased. Through the comparisons of the multi-element airfoils with Gurney flap with different types of slats, the optimized multi-element airfoil with higher lift coefficient and lower drag coefficient is obtained ultimately.

Aerodynamic Performance of Blended Wing Body Aircraft with Distributed Propulsion

2014 ◽  
Vol 1016 ◽  
pp. 354-358 ◽  
Author(s):  
Wan Fang Yan ◽  
Jiang Hao Wu ◽  
Yan Lai Zhang
Keyword(s):  
Lift Coefficient ◽  
Large Angle ◽  
Aerodynamic Performance ◽  
Propulsion System ◽  
System Configuration ◽  
High Lift ◽  
Distributed Propulsion ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Center Body

A 350-passenger BWB with a distributed propulsion system configuration is carried out and its aerodynamic performance in cruising and taking off are analyzed and discussed. It is shown from computation that the integrated configuration has a commendable aerodynamic performance in cruising and taking off. The cruise lift to drag ratio is reach to 24.0 in cruising. The ingestion effect of the propulsion system leads to a high lift at a low speed. The maximum lift coefficient CLmax is 1.62 when α=20° in taking off. In addition, the ingestion also delays the flow separation on the upper surface of center body, which contributes to a well stall performance of the configuration at large angle of attack.

STUDY ON AERODYNAMIC PERFORMANCE OF THE BIONIC AIRFOIL BASED ON THE SWALLOW'S WING

2013 ◽  
Vol 13 (06) ◽  
pp. 1340022 ◽  
Author(s):  
WEIJUN TIAN ◽  
FANGYUAN LIU ◽  
QIAN CONG ◽  
YURONG LIU ◽  
LUQUAN REN
Keyword(s):  
Wind Tunnel ◽  
Wind Turbines ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Performance ◽  
Wind Tunnel Tests ◽  
Small Wind Turbines ◽  
Aerodynamic Performances ◽  
Drag Ratio ◽  
Bionic Airfoil

This paper demonstrates the design of the airfoil of small wind turbines, the bionic airfoil was inspired by the morphology of the swallow's extended wing. The wind tunnel tests on the bionic and standard airfoils NACA4412 were conducted, and the aerodynamic performances of the airfoils were numerically investigated. The results show that the bionic airfoil has better aerodynamic performance, the lift coefficient and lift-drag ratio are larger than those of the NACA4412; with the angle of attack increases, both the bionic and standard airfoils stall, but the stall characteristics of the bionic airfoil are better.

scholarly journals Numerical Investigation of Performance Enhancement of the S809 Airfoil and Phase VI Wind Turbine Blade Using Co-Flow Jet Technology

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6933
Author(s):  
Shunlei Zhang ◽  
Xudong Yang ◽  
Bifeng Song
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Performance Enhancement ◽  
Lift Coefficient ◽  
Wind Turbine Blade ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Momentum Coefficient ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Making full use of wind energy can effectively alleviate the global energy shortage and environment contamination problems. Nevertheless, how to significantly improve the performance of the wind turbine airfoil and blade is a crucial issue. As the novel flow control method, the co-flow jet (CFJ) technology is one of the most potential methods to solve this problem. Thus, the effects of the CFJ technology on the performance enhancement of the S809 airfoil and Phase VI wind turbine blade are explored in this study. Furthermore, the effects of the injection location and jet momentum coefficient are studied, and an adaptive jet momentum coefficient strategy of the CFJ technology is proposed. Results demonstrate that the CFJ technology can significantly improve the maximum lift coefficient and maximum corrected lift-to-drag ratio of the S809 airfoil. Moreover, the power coefficient of the Phase VI wind turbine blade at the low tip speed ratio is greatly enhanced as well. In particular, the maximum lift coefficient and maximum corrected lift-to-drag ratio of the typical S809 CFJ airfoil with adaptive Cμ are improved by 119.7% and 36.2%, respectively. The maximum power coefficient of CFJ blade can be increased by 4.5%, and the power coefficient of CFJ blade can be boosted by 226.7% when the tip speed ratio is 1.52.

scholarly journals A Parametric Study of Trailing Edge Flap Implementation on Three Different Airfoils Through an Artificial Neuronal Network

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 828
Author(s):  
Igor Rodriguez-Eguia ◽  
Iñigo Errasti ◽  
Unai Fernandez-Gamiz ◽  
Jesús María Blanco ◽  
Ekaitz Zulueta ◽  
...  
Keyword(s):  
Aerodynamic Coefficients ◽  
Trailing Edge ◽  
High Lift ◽  
Trailing Edge Flaps ◽  
Artificial Neural Network Ann ◽  
Lift And Drag ◽  
Artificial Neuronal Network ◽  
Naca 0012 ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Trailing edge flaps (TEFs) are high-lift devices that generate changes in the lift and drag coefficients of an airfoil. A large number of 2D simulations are performed in this study, in order to measure these changes in aerodynamic coefficients and to analyze them for a given Reynolds number. Three different airfoils, namely NACA 0012, NACA 64(3)-618, and S810, are studied in relation to three combinations of the following parameters: angle of attack, flap angle (deflection), and flaplength. Results are in concordance with the aerodynamic results expected when studying a TEF on an airfoil, showing the effect exerted by the three parameters on both aerodynamic coefficients lift and drag. Depending on whether the airfoil flap is deployed on either the pressure zone or the suction zone, the lift-to-drag ratio, CL/CD, will increase or decrease, respectively. Besides, the use of a larger flap length will increase the higher values and decrease the lower values of the CL/CD ratio. In addition, an artificial neural network (ANN) based prediction model for aerodynamic forces was built through the results obtained from the research.

A comprehensive comparative investigation of the Lifting Line Theory and Blade Element Momentum Theory applied to small wind turbines

2021 ◽  
pp. 1-25
Author(s):  
K.A.R. Ismail ◽  
Willian Okita
Keyword(s):  
Wind Turbines ◽  
Power Coefficient ◽  
Computational Time ◽  
Local Flow ◽  
Small Wind Turbines ◽  
Wake Effects ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Blade Element

Abstract Small wind turbines are adequate for electricity generation in isolated areas to promote local expansion of commercial activities and social inclusion. Blade element momentum (BEM) method is usually used for performance prediction, but generally produces overestimated predictions since the wake effects are not precisely accounted for. Lifting line theory (LLT) can represent the blade and wake effects more precisely. In the present investigation the two methods are analyzed and their predictions of the aerodynamic performance of small wind turbines are compared. Conducted simulations showed a computational time of about 149.32 s for the Gottingen GO 398 based rotor simulated by the BEM and 1007.7 s for simulation by the LLT. The analysis of the power coefficient showed a maximum difference between the predictions of the two methods of about 4.4% in the case of Gottingen GO 398 airfoil based rotor and 6.3% for simulations of the Joukowski J 0021 airfoil. In the case of the annual energy production a difference of 2.35% is found between the predictions of the two methods. The effects of the blade geometrical variants such as twist angle and chord distributions increase the numerical deviations between the two methods due to the big number of iterations in the case of LLT. The cases analyzed showed deviations between 3.4% and 4.1%. As a whole, the results showed good performance of both methods; however the lifting line theory provides more precise results and more information on the local flow over the rotor blades.

scholarly journals Aerodynamic and Vibration Characteristics of the Micro-Octocopter at Low Reynolds Number

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohua Zou ◽  
Mingsheng Ling ◽  
Wenzheng Zhai
Keyword(s):  
Reynolds Number ◽  
Load Capacity ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Vibration Characteristics ◽  
Low Reynolds ◽  
Vibration Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

With the development of flight technology, the need for stable aerodynamic and vibration performance of the aircraft in the civil and military fields has gradually increased. In this case, the requirements for aerodynamic and vibration characteristics of the aircraft have also been strengthened. The existing four-rotor aircraft carries limited airborne equipment and payload, while the current eight-rotor aircraft adopts a plane layout. The size of the propeller is generally fixed, including the load capacity. The upper and lower tower layout analyzed in this paper can effectively solve the problems of insufficient four-axis load and unstable aerodynamic and vibration performance of the existing eight-axis aircraft. This paper takes the miniature octorotor as the research object and studies the aerodynamic characteristics of the miniature octorotor at different low Reynolds numbers, different air pressures and thicknesses, and the lift coefficient and lift-to-drag ratio, as well as the vibration under different elastic moduli and air pressure characteristics. The research algorithm adopted in this paper is the numerical method of fluid-solid cohesion and the control equation of flow field analysis. The research results show that, with the increase in the Reynolds number within a certain range, the aerodynamic characteristics of the miniature octorotor gradually become better. When the elastic modulus is 2.5 E, the aircraft’s specific performance is that the lift increases, the critical angle of attack increases, the drag decreases, the lift-to-drag ratio increases significantly, and the angle of attack decreases. However, the transition position of the flow around the airfoil surface is getting closer to the leading edge, and its state is more likely to transition from laminar flow to turbulent flow. When the unidirectional carbon fiber-reinforced thickness is 0.2 mm and the thin arc-shaped airfoil with the convex structure has a uniform thickness of 2.5% and a uniform curvature of 4.5%, the aerodynamic and vibration characteristics of the octorotor aircraft are most beneficial to flight.

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