Modeling of Rain Drop Erosion in a Multi-MW Wind Turbine

2015 ◽  
Author(s):  
Alessandro Corsini ◽  
Alessio Castorrini ◽  
Enrico Morei ◽  
Franco Rispoli ◽  
Fabrizio Sciulli ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Design Stage ◽  
Base Line ◽  
Horizontal Axis Wind Turbine ◽  
Relevant Effect ◽  
The Impact ◽  
Rain Erosion

The actual strategy in offshore wind energy development is oriented to the progressive increase of the turbine diameter as well as the per unit power. Among many pioneering technological and aerodynamic issues linked to this design trend, the wind velocity at the blade tip region reaches very high values in normal operating conditions (typically between 90 to 110 m/s). In this range of velocity, the rain erosion phenomenon can have a relevant effect on the overall turbine performance in terms of power and energy production (up to 20% loss in case of deeply eroded leading edge). Therefore, as a customary approach erosion related issues are accounted for in the scheduling of the wind turbine maintenance. When offshore, on the other hand, the criticalities inherent to the cost of maintenance and operation monitoring suggest the rain erosion concerns to be tackled at the turbine design stage. In so doing, the use of computational tools to study the erosion phenomenon of wind turbines under severe meteorological conditions could define the base-line approach in the wind turbine blades design and verification. In this work, the authors present a report on numerical prediction of erosion on a 6 MW HAWT (horizontal axis wind turbine). Two different blade geometries of different aerodynamic loading, have been studied in a view to explore their sensitivity to rain erosion. The fully 3D simulations are carried out using an Euler-Lagrangian approach. Flow field simulations are carried out with the open-source code OpenFOAM, based on a finite volume approach, using Multiple Reference Frame methodology. Reynolds Averaged Navier-Stokes equations for incompressible steady flow were solved with a k-ε turbulence. An in-house code (P-Track) is used to compute the rain drops transport and dispersion, adopting the Particle Cloud Tracking approach (PCT), already validated on large industrial turbomachinery. At the impact on blade, erosion is modelled accounting for the main quantities affecting the phenomenon, which are impact velocity and material properties of the target surface. Results provide the regions of the two blades more sensitive to erosion, and the effect of the blade geometry on erosion attitude.

Improvements in the Power Output of a Horizontal Axis Wind Turbine Due to the Introduction of a Curved Blade

2002 ◽  
Author(s):  
Erin K. Clarke ◽  
Sylvester Abanteriba
Keyword(s):  
Wind Tunnel ◽  
Flow Visualization ◽  
Wind Turbine ◽  
Power Output ◽  
Turbine Blades ◽  
Horizontal Axis Wind Turbine ◽  
Modified Model ◽  
Curved Blade ◽  
Generation Capacity ◽  
The Impact

This paper examines the impact on the power generation capacity of a wind turbine as a result of the modification of the shape of the blades of an existing wind turbine. The modification involves curving the blades in the direction of rotation resulting in an increase in generated lift and therefore an increase in the power output of the wind turbine. Two three-bladed models were tested in a wind tunnel, one original straight-bladed model and one modified model both of which were 0.84 m in diameter. A study of the methods of flow visualization for a wind turbine in a wind tunnel was investigated. The corresponding results are presented. It was discovered that the china clay method of flow visualization in conjunction with a strobe light gave a good indication of the direction of the airflow over the turbine blades as did condensed oil droplets from a smoke wand which presented a very clear indication of the span-wise flow. It was concluded from the investigation that curving the blade into the direction of rotation on a wind turbine produced a greater power output at the same wind speed as an unmodified wind turbine.

Structural design and analysis of large wind turbine blade

2019 ◽  
Vol 33 (14n15) ◽  
pp. 1940032
Author(s):  
Sung-Youl Bae ◽  
Yun-Hae Kim
Keyword(s):  
Wind Turbine ◽  
Structural Design ◽  
Turbine Blades ◽  
Design Procedure ◽  
Operating Conditions ◽  
Design Stage ◽  
Evaluation Procedure ◽  
Integrity Assessment ◽  
Design Specifications ◽  
Large Wind

This paper presents a new design procedure for large wind turbine blades, which can be used in various case studies. The structural design of 2MW CFRP blade was performed using a verified 2MW GFRP blade model. The structural integrity assessment of the CFRP model demonstrated that the design criteria for tip deformation, buckling failure, and laminate failure in normal wind turbine operating conditions were met. The existing aero-elastic analysis code was not used to estimate the blade load, but the blade’s surface pressure was calculated using CFD. The conventional load analysis code necessitates the establishment of a turbine system and the input of structural characteristics with changes in the structural design specifications. However, when CFD was used to estimate the load, the turbine system was not required and the structure was evaluated against various design cases, making this a useful approach in preliminary design. This new structural design and evaluation procedure for wind blades can be used to review diverse design specifications in the initial design stage.

Numerical Modeling of the Effects of Leading-Edge Erosion and Trailing-Edge Damage on Wind Turbine Loads and Performance

2020 ◽  
Author(s):  
Francesco Papi ◽  
Lorenzo Cappugi ◽  
Alessandro Bianchini ◽  
Sebastian Perez-Becker
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Prolonged Exposure ◽  
Turbine Blades ◽  
Leading Edge ◽  
Future Generation ◽  
Operating Conditions ◽  
Wind Speeds ◽  
Extreme Loads ◽  
The Impact

Abstract Wind turbines often operate in challenging environmental conditions. In hot and dusty climates, wind turbine blades are constantly exposed to abrasive particles that, according to many field reports, cause significant damages to the blade’s leading edge. On the other hand, in cold climates similar effects can be caused by prolonged exposure to hail and rain. Quantifying the effects of airfoil deterioration on modern multi-MW wind turbines is crucial to correctly schedule maintenance and to forecast the potential impact on productivity. Analyzing the impact of airfoil damage on fatigue and extreme loading is also important to improve the reliability and longevity of wind turbines. However, this is a topic that has not yet been extensively investigated. In this work, a blade erosion model is developed and calibrated using Computational Fluid Dynamics (CFD). The DTU 10MW Reference Wind Turbine (RWT) is selected as the case study for the analysis, as it is representative of the typical size of the future generation wind turbines. Lift and Drag polars are generated using the developed model and a CFD numerical set-up. Power and torque coefficients are compared in idealized conditions at two wind speeds, i.e. the rated speed and one below it. Full aero-servo-elastic simulations of the turbine are conducted with the eroded polars using NREL’s BEM-based code OpenFAST. Sixty-six ten-minute simulations are performed for each stage of airfoil damage, reproducing operating conditions specified by the IEC 61400-1 power production DLC-group, including wind shear, yaw misalignment and turbulence. Performance data, fatigue and extreme loads are compared for the aeroelastic simulations, showing maximum decreases in CP of about 12% as well as reductions in fatigue and extreme loading.

scholarly journals Numerical Investigation of Passive Vortex Generators on a Wind Turbine Airfoil Undergoing Pitch Oscillations

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 654 ◽  
Author(s):  
Chengyong Zhu ◽  
Tongguang Wang ◽  
Jianghai Wu
Keyword(s):  
Wind Turbine ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Vortex Generators ◽  
Dynamic Stall ◽  
Wind Turbine Blades ◽  
Unsteady Aerodynamic ◽  
Wind Turbine Airfoil ◽  
Airfoil Flow

Passive vortex generators (VGs) are widely used to suppress the flow separation of wind turbine blades, and hence, to improve rotor performance. VGs have been extensively investigated on stationary airfoils; however, their influence on unsteady airfoil flow remains unclear. Thus, we evaluated the unsteady aerodynamic responses of the DU-97-W300 airfoil with and without VGs undergoing pitch oscillations, which is a typical motion of the turbine unsteady operating conditions. The airfoil flow is simulated by numerically solving the unsteady Reynolds-averaged Navier-Stokes equations with fully resolved VGs. Numerical modelling is validated by good agreement between the calculated and experimental data with respect to the unsteady-uncontrolled flow under pitch oscillations, and the steady-controlled flow with VGs. The dynamic stall of the airfoil was found to be effectively suppressed by VGs. The lift hysteresis intensity is greatly decreased, i.e., by 72.7%, at moderate unsteadiness, and its sensitivity to the reduced frequency is favorably reduced. The influences of vane height and chordwise installation are investigated on the unsteady aerodynamic responses as well. In a no-stall flow regime, decreasing vane height and positioning VGs further downstream can lead to relatively high effectiveness. Compared with the baseline VG geometry, the smaller VGs can decrease the decay exponent of nondimensionalized peak vorticity by almost 0.02, and installation further downstream can increase the aerodynamic pitch damping by 0.0278. The obtained results are helpful to understand the dynamic stall control by means of conventional VGs and to develop more effective VG designs for both steady and unsteady wind turbine airfoil flow.

Inclusion of a Simple Dynamic Inflow Model in the Blade Element Momentum Theory for Wind Turbine Application

2014 ◽  
Author(s):  
Xiaomin Chen ◽  
Ramesh Agarwal
Keyword(s):  
Steady State ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Phase Iii ◽  
Speed Ratio ◽  
Horizontal Axis Wind Turbine ◽  
Bem Theory ◽  
Blade Element

It is well established that the power generated by a Horizontal-Axis Wind Turbine (HAWT) is a function of the number of blades B, the tip speed ratio λr (blade tip speed/wind free-stream velocity) and the lift to drag ratio (CL/CD) of the airfoil sections of the blade. The previous studies have shown that Blade Element Momentum (BEM) theory is capable of evaluating the steady-state performance of wind turbines, in particular it can provide a reasonably good estimate of generated power at a given wind speed. However in more realistic applications, wind turbine operating conditions change from time to time due to variations in wind velocity and the aerodynamic forces change to new steady-state values after the wake settles to a new equilibrium whenever changes in operating conditions occur. The goal of this paper is to modify the quasi-steady BEM theory by including a simple dynamic inflow model to capture the unsteady behavior of wind turbines on a larger time scale. The output power of the wind turbines is calculated using the improved BEM method incorporating the inflow model. The computations are performed for the original NREL Phase II and Phase III turbines and the Risoe turbine all employing the S809 airfoil section for the turbine blades. It is shown by a simple example that the improved BEM theory is capable of evaluating the wind turbine performance in practical situations where operating conditions often vary in time.

Blade Dynamic Stall Vortex Kinematics for a Horizontal Axis Wind Turbine in Yawed Conditions*

2001 ◽  
Vol 123 (4) ◽  
pp. 272-281 ◽  
Author(s):  
Scott J. Schreck ◽  
Michael C. Robinson ◽  
M. Maureen Hand ◽  
David A. Simms
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Unsteady Aerodynamics ◽  
Horizontal Axis ◽  
Dynamic Stall ◽  
Deformation Analysis ◽  
Horizontal Axis Wind Turbine ◽  
The Impact ◽  
Vortex Kinematics

Horizontal axis wind turbines routinely suffer significant time varying aerodynamic loads that adversely impact structures, mechanical components, and power production. As lighter and more flexible wind turbines are designed to reduce overall cost of energy, greater accuracy and reliability will become even more crucial in future aerodynamics models. However, to render calculations tractable, current modeling approaches admit various approximations that can degrade model predictive accuracy. To help understand the impact of these modeling approximations and improve future models, the current effort seeks to document and comprehend the vortex kinematics for three-dimensional, unsteady, vortex dominated flows occurring on horizontal axis wind turbine blades during non-zero yaw conditions. To experimentally characterize these flows, the National Renewable Energy Laboratory Unsteady Aerodynamics Experiment turbine was erected in the NASA Ames 80 ft×120 ft wind tunnel. Then, under strictly-controlled inflow conditions, turbine blade surface pressures and local inflow velocities were acquired at multiple radial locations. Surface pressure histories and normal force records were used to characterize dynamic stall vortex kinematics and normal forces. Stall vortices occupied approximately two-thirds of the aerodynamically active blade span and persisted for nearly one-fourth of the blade rotation cycle. Stall vortex convection varied dramatically along the blade radius, yielding pronounced dynamic stall vortex deformation. Analysis of these data revealed systematic alterations to vortex kinematics due to changes in test section speed, yaw error, and blade span location.

scholarly journals EFFECT OF SMART STRUCTURES ON AERODYNAMIC PERFORMANCE OF HORIZONTAL AXIS WIND TURBINE

2021 ◽  
Vol 5 (11) ◽  
Author(s):  
Hira Syed ◽  
Dr.Gulraiz Ahmed
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Stokes Equations ◽  
Smart Structures ◽  
Turbine Blades ◽  
Cost Effective ◽  
Aerodynamic Performance ◽  
Horizontal Axis Wind Turbine ◽  
Aerodynamic Analysis ◽  
Cord Length

In renewable energy the wind energy is the most significant source. The wind turbine suppresses the kinetic energy of the wind. Current research focuses on improving the aerodynamic performance of wind turbine blades through wind tunnel tests and theoretical studies. These exercises are time taking and require considerable laboratory resources. Similarly, simulation of wind turbines using CFD software (Computational Fluid Dynamics) provides cost-effective solutions for aerodynamic analysis of the blades. Due to the energy crisis in Pakistan, we need a solution to overcome the power shortage. Wind energy is an economical and affordable energy. In this study, two-dimensional airfoil S4310, was selected for the blade cross section. 2.1 m cord length from root and 0.67 m cord length from tip of the blade, aerodynamic analysis of this model was performed using ANSYS-FLUENT software. Using the turbulence model, the lift and drag coefficients were computed for wind-turbine blade at 0?-14? angles of attack (AOA). The CFD results accomplish by all together solving momentum ,continuity and the Navier-Stokes equations using a standard non-linear solver. The smart structures were also applied on the wing in which active twist was applied to the blade using twist angles from 0?-10? and similarly the lift to drag ratio were considered.

Experimental investigations and aerodynamic shape optimization of small horizontal axis wind turbine blades

2021 ◽  
Author(s):  
Manoj Kumar Chaudhary ◽  
S Prakash
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Research Work ◽  
Horizontal Axis ◽  
Power Coefficient ◽  
Wind Turbine Blades ◽  
Horizontal Axis Wind Turbine ◽  
The Impact ◽  
Blade Geometry

This paper aims to optimize and investigate the small horizontal axis wind turbine blades at low wind speed. The objective of this research work is to explain the design method based on BEM theory for 0.2 m blade rotors with constant, variable and linear chord with twisted blade geometry. MATLAB and Xfoil programs were used for BEM principles and wind turbines with SG6043 airfoil. A numerical and experimental study was carried out to examine the impact of rotor solidity from 0.057 to 0.207 and the number of blades from 3 to 7 in this research work. The experimental blades were developed by using the 3D printing additive manufacturing technique. The investigation of the rotors has been done in an open wind tunnel, at wind speed from 2 to 8 m/s. The initial investigation range included tip speed ratios from 2 to 8, and angle of attacks from 2 to 20°. Later on these parameters were varied in Matlab and Xfoil software optimization and investigation of the power coefficient, blade geometry, number of blades and blade pitch angle. It was found that the rotor solidity 0.055 to 0.085 displayed better performances.

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