sHAWT Design: Airfoil Aerodynamics Under the Influence of Roughness

2016 ◽  
Author(s):  
D. Holst ◽  
G. Pechlivanoglou ◽  
C. T. Kohlrausch ◽  
C. N. Nayeri ◽  
C. O. Paschereit
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
High Performance ◽  
Experimental Testing ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Small Surface ◽  
Horizontal Axis Wind Turbines ◽  
Low Reynolds ◽  
Utility Scale

Small horizontal axis wind turbines (sHAWTs) are mostly designed by smaller companies with no or just small possibilities of aerodynamic testing and hence, airfoil selection is often based on published performance data and minimal or no experimental testing from the blade designer’s side. This paper focuses on the aerodynamic consequences resulting from an unqualified airfoil selection and accumulating surface soiling. The high performance low Reynolds profile FX 63-137 is compared to an Eppler-338 wing section as well as to a high performance utility scale wind turbine airfoil, AH 93-W-174 -1ex. We extensively investigated these three different airfoils within the low Reynolds regime between 50,000 and 200,000. This regime is especially important for the starting behavior of a wind turbine, i.e. a quick speed up, and is crucial for small wind turbines because they have more frequent start/stop events. A Reynolds number of 200 k is additionally the operational regime of some sHAWT under the 5–10 kW level. The present study discusses not only the low Reynolds performance of the smooth profiles but investigates the influence of surface soiling. This ranges from 2D disturbances, such as a 0.2mm thin tripwire or several zigzag tapes, up to the simulation of massive sand build up by covering the entire leading edge region with a 40 grit sand paper. The experiments reveal that even small surface soiling has an impact and massive roughness leads in some cases to the loss of 50% in lift coefficient. The experimental data is used to simulate a sHAWT in different stages of debris. While the peak power was reduced by two thirds compared to the clean configuration the annual energy production has halved under certain conditions.

Potential of Retrofit Passive Flow Control for Small Horizontal Axis Wind Turbines

2016 ◽  
Author(s):  
D. Holst ◽  
G. Pechlivanoglou ◽  
F. Wegner ◽  
C. N. Nayeri ◽  
C. O. Paschereit
Keyword(s):  
Flow Control ◽  
Wind Turbines ◽  
High Performance ◽  
Horizontal Axis ◽  
Vortex Generators ◽  
Passive Flow Control ◽  
Wind Speeds ◽  
Passive Flow ◽  
Horizontal Axis Wind Turbines ◽  
Low Reynolds

The present paper analyzes the effect of passive flow control (PFC) with respect to the retrofitting on small horizontal axis wind turbines (sHAWT). We conducted extensive wind tunnel studies on an high performance low Reynolds airfoil using different PFC elements, i.e. vortex generators (VGs) and Gurney flaps. QBlade, an open source Blade Element Momentum (BEM) code, is used to study the retrofitting potential of a simulated small wind turbine. The turbine design is presented and discussed. The simulations include the data and polars gained from the experiments and give further insight into the effects of PFC on sHAWT. Therefore several different blades were simulated using several variations of VG positions. This paper discusses their influence on the turbine performance. The authors focus especially on the start-up performance as well as achieving increased power output at lower wind speeds. The vortex generators reduce the risk of laminar separation and enhance the lift in some configurations by more than 40% at low Reynolds numbers.

Potential of Retrofit Passive Flow Control for Small Horizontal Axis Wind Turbines

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
D. Holst ◽  
G. Pechlivanoglou ◽  
F. Wegner ◽  
C. N. Nayeri ◽  
C. O. Paschereit
Keyword(s):  
Flow Control ◽  
Wind Turbines ◽  
High Performance ◽  
Horizontal Axis ◽  
Vortex Generators ◽  
Passive Flow Control ◽  
Wind Speeds ◽  
Passive Flow ◽  
Horizontal Axis Wind Turbines ◽  
Low Reynolds

The present paper analyzes the effect of passive flow control (PFC) with respect to the retrofitting on small horizontal axis wind turbines (sHAWTs). We conducted extensive wind tunnel studies on a high performance low Reynolds airfoil using different PFC elements, i.e., vortex generators (VGs) and Gurney flaps (GF). qblade, an open source blade element momentum (BEM) code, is used to study the retrofitting potential of a simulated small wind turbine. The turbine design is presented and discussed. The simulations include the data and polars gained from the experiments and give further insight into the effects of PFC on sHAWTs. Therefore, several different blades were simulated using several variations of VG positions. This paper discusses their influence on the turbine performance. The authors especially focus on the startup performance as well as achieving increased power output at lower wind speeds. The vortex generators reduce the risk of laminar separation and enhance the lift in some configurations by more than 40% at low Reynolds numbers.

Novel Tubercle Design for a Wind Turbine Blade Operating at Low Reynolds Number

2019 ◽  
Author(s):  
R. Deeksha ◽  
Mahesh K. Varpe
Keyword(s):  
Reynolds Number ◽  
Wind Turbine ◽  
Amplitude Ratio ◽  
Low Reynolds Number ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Operating Condition ◽  
Low Reynolds

Abstract Wind energy has become one of the vital sustainable energy resources and a leading contender to the renewable resources race. The need of extending the aerodynamic performance of a wind turbine paved the way for radical approaches in the design of wind turbine blades. One such promising technique is the adoption of passive flow controls like leading edge protuberance or tubercles. In this paper the aerodynamic performance of NACA0009 (baseline) superimposed with a leading edge protuberance is numerically investigated in the post-stall operating conditions. The investigation objective was to identify the optimum pitch to amplitude ratio of the protuberance in the post stall operating condition for a low Reynolds number of 5 × 104. Computational fluid dynamics computations were performed using κ-ω SST turbulence model. The optimum pitch to amplitude ratio was found to be 6 which enhanced the aerodynamic lift coefficient by 42% in the post stall operating condition. The lift is reduced at lower AOA but gets complement in the post stall operating conditions.

Experimental investigations of flow over NACA airfoils 0021 and 4412 of wind turbine blades with and without Tubercles

2021 ◽  
pp. 0309524X2110071
Author(s):  
Usman Butt ◽  
Shafqat Hussain ◽  
Stephan Schacht ◽  
Uwe Ritschel
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Wind Turbine ◽  
Critical Region ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Experimental Investigations ◽  
Wind Turbine Blades

Experimental investigations of wind turbine blades having NACA airfoils 0021 and 4412 with and without tubercles on the leading edge have been performed in a wind tunnel. It was found that the lift coefficient of the airfoil 0021 with tubercles was higher at Re = 1.2×105 and 1.69×105 in post critical region (at higher angle of attach) than airfoils without tubercles but this difference relatively diminished at higher Reynolds numbers and beyond indicating that there is no effect on the lift coefficients of airfoils with tubercles at higher Reynolds numbers whereas drag coefficient remains unchanged. It is noted that at Re = 1.69×105, the lift coefficient of airfoil without tubercles drops from 0.96 to 0.42 as the angle of attack increases from 15° to 20° which is about 56% and the corresponding values of lift coefficient for airfoil with tubercles are 0.86 and 0.7 at respective angles with18% drop.

Fast CFD Simulation of Horizontal Axis Wind Turbines

2010 ◽  
Author(s):  
Fabio De Bellis ◽  
Luciano A. Catalano ◽  
Andrea Dadone
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Cfd Simulation ◽  
Flow Distribution ◽  
Horizontal Axis ◽  
Wall Functions ◽  
Mesh Topology ◽  
Numerical Predictions ◽  
Horizontal Axis Wind Turbines ◽  
Time Required

The numerical simulation of horizontal axis wind turbines (HAWT) has been analysed using computational fluid dynamics (CFD) with the aim of obtaining reliable but at the same time affordable wind turbine simulations, while significantly reducing required overall resources (time, computational power, user skills), for example in an optimization perspective. Starting from mesh generation, time required to extract preliminary aerodynamic predictions of a wind turbine blade has been shortened by means of some simplifications, i.e.: fully unstructured mesh topology, reduced grid size, incompressible flow assumption, use of wall functions, commercial available CFD package employment. Ansys Fluent software package has been employed to solve Reynolds Averaged Navier Stokes (RANS) equations, and results obtained have been compared against NREL Phase VI campaign data. The whole CFD process (pre-processing, processing, postprocessing) has been analysed and the chosen final settings are the result of a trade-off between numerical accuracy and required resources. Besides the introduced simplifications, numerical predictions of shaft torque, forces and flow distribution are in good agreement with experimental data and as accurate as those calcuted by other more sophisticated works.

Vertical axis wind turbine operation in icing conditions: A review study

2021 ◽  
pp. 0309524X2110618
Author(s):  
Syed Abdur Rahman Tahir ◽  
Muhammad Shakeel Virk
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Electricity Production ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Horizontal Axis Wind Turbines ◽  
Promising Solution ◽  
Review Study ◽  
Accretion Physics

Vertical Axis Wind Turbine (VAWT) can be a promising solution for electricity production in remote ice prone territories of high north, where good wind resources are available, but icing is a challenge that can affect its optimum operation. A lot of research has been made to study the icing effects on the conventional horizontal axis wind turbines, but the literature about vertical axis wind turbines operating in icing conditions is still scarce, despite the importance of this topic. This paper presents a review study about existing knowledge of VAWT operation in icing condition. Focus has been made in better understanding of ice accretion physics along VAWT blades and methods to detect and mitigate icing effects.

scholarly journals Design and Testing of a LUT Airfoil for Straight-Bladed Vertical Axis Wind Turbines

2018 ◽  
Vol 8 (11) ◽  
pp. 2266 ◽  
Author(s):  
Shoutu Li ◽  
Ye Li ◽  
Congxin Yang ◽  
Xuyao Zhang ◽  
Qing Wang ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Optimization Method ◽  
Geometrical Parameters ◽  
Vertical Axis Wind Turbines ◽  
University Of Technology ◽  
Horizontal Axis Wind Turbines

The airfoil plays an important role in improving the performance of wind turbines. However, there is less research dedicated to the airfoils for Vertical Axis Wind Turbines (VAWTs) compared to the research on Horizontal Axis Wind Turbines (HAWTs). With the objective of maximizing the aerodynamic performance of the airfoil by optimizing its geometrical parameters and by considering the law of motion of VAWTs, a new airfoil, designated the LUT airfoil (Lanzhou University of Technology), was designed for lift-driven VAWTs by employing the sequential quadratic programming optimization method. Afterwards, the pressure on the surface of the airfoil and the flow velocity were measured in steady conditions by employing wind tunnel experiments and particle image velocimetry technology. Then, the distribution of the pressure coefficient and aerodynamic loads were analyzed for the LUT airfoil under free transition. The results show that the LUT airfoil has a moderate thickness (20.77%) and moderate camber (1.11%). Moreover, compared to the airfoils commonly used for VAWTs, the LUT airfoil, with a wide drag bucket and gentle stall performance, achieves a higher maximum lift coefficient and lift–drag ratios at the Reynolds numbers 3 × 105 and 5 × 105.

scholarly journals New airfoils for micro horizontal-axis wind turbines

2021 ◽  
Author(s):  
Manoj Kumar Chaudhary ◽  
◽  
S. Prakash ◽  
Keyword(s):  
Reynolds Number ◽  
Wind Turbines ◽  
Low Reynolds Number ◽  
Horizontal Axis ◽  
Speed Ratio ◽  
Maximum Output ◽  
Horizontal Axis Wind Turbine ◽  
Horizontal Axis Wind Turbines ◽  
Low Reynolds ◽  
Bem Theory

In this study, small horizontal-axis wind turbine blades operating at low wind speeds were optimized. An optimized blade design method based on blade element momentum (BEM) theory was used. The rotor radius of 0.2 m, 0.4 m and 0.6 m and blade geometry with single (W1 & W2) and multistage rotor (W3) was examined. MATLAB and XFoil programs were used to implement to BEM theory and devise a six novel airfoil (NAF-Series) suitable for application of small horizontal axis wind turbines at low Reynolds number. The experimental blades were developed using the 3D printing additive manufacturing technique. The new airfoils such as NAF3929, NAF4420, NAF4423, NAF4923, NAF4924, and NAF5024 were investigated using XFoil software at Reynolds numbers of 100,000. The investigation range included tip speed ratios from 3 to 10 and angle of attacks from 2° to 20°. These parameters were varied in MATLAB and XFoil software for optimization and investigation of the power coefficient, lift coefficient, drag coefficient and lift-to-drag ratio. The cut-in wind velocity of the single and multistage rotors was approximately 2.5 & 3 m/s respectively. The optimized tip speed ratio, axial displacement and angle of attack were 5.5, 0.08m & 6° respectively. The proposed NAF-Series airfoil blades exhibited higher aerodynamic performances and maximum output power than those with the base SG6043 and NACA4415 airfoil at low Reynolds number.

A Computational Fluid Dynamics Analysis of Turbulence and Wakes of Horizontal Axis Wind Turbines During Non-Operational Time Periods

2020 ◽  
Author(s):  
Hussein Al-Qarishey ◽  
Robert W. Fletcher
Keyword(s):  
Wind Turbines ◽  
Unstructured Grid ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Horizontal Axis ◽  
Computational Fluid Dynamics Analysis ◽  
Horizontal Axis Wind Turbines ◽  
Wind Velocities ◽  
Utility Scale ◽  
Operational Time

Abstract Wind turbines can create turbulence and downstream wakes which can introduce generation losses of downstream impacted turbines. These downstream turbine-induced losses are due to two different conditions. The first is from power-producing rotating blades of upstream wind turbines agitating the subsequent downstream wind in a cork-screw like manner. The second is from non-rotating, non-operational, non-power-generating wind turbines. These non-operating turbines may be under scheduled service shutdown, or rendered non-functional due to longer-term or permanent mechanical problems. In this work CFD was used to study downstream turbulence and wakes of a utility-scale, non-operational three-blade horizontal axis wind turbines (HAWT). A flow field was constructed using an unstructured grid around a HAWT (rotor hub elevation of 80 meters and a blade length of 40 meters). Various wind velocities were studied up to 25 meters per second. Incompressible flow was used to assess downstream turbulence using a three-dimensional steady state and unsteady state SST k-ω (two equation) turbulence model. Different blade positions with respect to angle of attack (α) were studied, with a 4 degree angle of attack reported here. Pressures and velocities for distances of 100 meters in front and 500 meters downstream from the wind turbine are reported.

The design of a small lab-scale wind turbine model with high performance similarity to its utility-scale prototype

2020 ◽  
Vol 149 ◽  
pp. 435-444 ◽  
Author(s):  
B. Li ◽  
D.L. Zhou ◽  
Y. Wang ◽  
Y. Shuai ◽  
Q.Z. Liu ◽  
...  
Keyword(s):  
Wind Turbine ◽  
High Performance ◽  
Utility Scale ◽  
Turbine Model
Sign in / Sign up

Export Citation Format

Share Document