scholarly journals Sensitivity of the Hawt noise level predicted based on Amiet’s theory on the value of a turbulence intensity coefficient determined numerically

2018 ◽  
Vol 46 ◽  
pp. 00026
Author(s):  
Katarzyna Suder-Dębska ◽  
Dawid Romik ◽  
Ireneusz Czajka
Keyword(s):  
Numerical Modeling ◽  
Wind Turbine ◽  
Turbulence Intensity ◽  
Noise Level ◽  
Far Field ◽  
Intensity Coefficient ◽  
Ansys Fluent ◽  
Sst Turbulence Model ◽  
Turbine Airfoils ◽  
Naca 0012

In the paper the authors presented and compared two methods of the HAWT noise predicting. The priority, however, was to test the possibility of using Amiet's theory to determine the noise value in the far field. In this theory it is necessary to know the value of the turbulence intensity coefficient. The value of this coefficient was determined based on numerical modeling. The NACA 0012 profile was used for the airfoil shape. The ANSYS/Fluent program was used for numerical calculations, where the k-ω SST turbulence model was used to simulate the flow, and Ffocs- Williams and Hawkings model was used to determine the noise level. The turbulence intensity coefficient estimated in this way was then used to determine the noise value from the wind turbine airfoils using Amiet's theory.

scholarly journals Numerical efficiency evaluation of a vertical axis turbine equipped with 4 digits and 5 digits NACA airfoils

2019 ◽  
Vol 85 ◽  
pp. 03001
Author(s):  
Florina Costea ◽  
Ion Malael
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Scientific Paper ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Renewable Energy Resources ◽  
Ansys Fluent ◽  
Sst Turbulence Model ◽  
Fluent Software ◽  
Shape Influence

In the current age of global energy crisis, a run for the use of renewable energy resources as the wind energy has gained a significant attention. The main objective of this study is the comparison between two wind turbine configurations. These two turbines have the same geometric parameters but one with a 4 digits NACA0018 blades and the other with 5 digits NACA63-415 blades. In this scientific paper, a numerical evaluation of the airfoil shape influence on the VAWT efficiency is done. For this study the CFD methods with Ansys Fluent software, are used. All the simulations are for unsteady flow at 1e06 Reynolds number value with SST turbulence model. At the design point the wind velocity is 12 m/s and for the wind turbine geometric features, the diameter is 3.25m and the height 4.87m. The power coefficient variation through tip speed ratio will be represented for each wind turbine configurations. To estimate the recirculation zone effects on the efficiency, the vorticity magnitude contours are presented for different positions of the blades. The results will indicate the feasibility of optimization of future wind turbine more complex airfoils.

scholarly journals Mesh Properties for RANS Simulations of Airfoil-Shaped Profiles: A Case Study of Rudder Hydrodynamics

2021 ◽  
Vol 9 (10) ◽  
pp. 1062
Author(s):  
Suli Lu ◽  
Jialun Liu ◽  
Robert Hekkenberg
Keyword(s):  
Near Field ◽  
Reynolds Numbers ◽  
Far Field ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Marine Propellers ◽  
Computational Fluid Dynamics Cfd ◽  
Naca 0012 ◽  
Mesh Properties

A good mesh is a prerequisite for achieving reliable results from Computational Fluid Dynamics (CFD) calculations. Mesh properties include mesh types, computational domain sizes, and node distributions. However, in literature, we found no clear consensus about what these properties should be. In this article, we performed a case study on ship rudders to determine what the suitable mesh properties are for airfoil-shaped profiles. A classic NACA 0012 profile is chosen as an example, and commercial packages ANSYS ICEM are applied for meshing with an ANSYS Fluent solver. With a strategy in consideration of relationships among different mesh properties, a comprehensive parametric investigation is conducted to study the impacts of these properties on the accuracy of rudder hydrodynamic coefficients obtained by CFD methods. The step-by-step study outputs recommended Reynolds numbers, domain sizes, and near- and far-field node distributions for mesh types with distinct topology structures, i.e., C-mesh, O-mesh, H-mesh, and Hybrid-mesh. Specifically, the study shows that a critical Reynolds number is needed for the perspective of efficiency, while a domain extending 60 times of the chord length enables the boundary effects to be negligible. As for node distributions, the near-field nodes should be treated carefully, compared with those in the far-field. After that, corresponding mesh properties for different calculation objectives are illustrated in detail based on the characteristics of mesh types mentioned above. With the proposed strategy for mesh refinements, impacts of different mesh properties on rudder hydrodynamics are clarified and recommended settings are applicable for other airfoil-shaped profiles such as wind turbines and marine propellers.

Numerical modeling of the flow over wind turbine airfoils by means of Spalart–Allmaras local correlation based transition model

Energy ◽  
2017 ◽  
Vol 130 ◽  
pp. 402-419 ◽  
Author(s):  
Valerio D'Alessandro ◽  
Sergio Montelpare ◽  
Renato Ricci ◽  
Andrea Zoppi
Keyword(s):  
Numerical Modeling ◽  
Wind Turbine ◽  
Transition Model ◽  
Local Correlation ◽  
Turbine Airfoils

Applications of a Coupled Methodology to the Wind Turbine Airfoils

2012 ◽  
Vol 516-517 ◽  
pp. 572-576
Author(s):  
Qing Yuan Chen ◽  
Feng Lin Guo ◽  
Jin Quan Xu
Keyword(s):  
Wind Turbine ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Far Field ◽  
Two Dimensional ◽  
Aerodynamic Coefficients ◽  
Free Vortex ◽  
Vortex Model ◽  
Wind Tunnel Data ◽  
Turbine Airfoils

In this study, a coupled methodology is proposed for the aerodynamic behavior of wind turbine airfoils. The idea is to combine a Navier-Stokes solver with a free vortex model. The zone for the calculation of CFD is confined to the surrounding of the airfoil, whilst the free vortex model accounts for the far field of the airfoil. The flow around the airfoil is assumed to be two-dimensional (2D) incompressible fully turbulent flow, which is modeled by two equation turbulence models. The computed aerodynamic coefficients are presented for two wind turbine airfoils and compared with wind tunnel data.

scholarly journals Design-Assisted of Pitching Aerofoils through Enhanced Identification of Coherent Flow Structures

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 11 ◽  
Author(s):  
Filippo Avanzi ◽  
Francesco De Vanna ◽  
Yin Ruan ◽  
Ernesto Benini
Keyword(s):  
Pressure Field ◽  
Navier Stokes ◽  
Flow Structures ◽  
Coupled Modes ◽  
Spectral Reconstruction ◽  
Sst Turbulence Model ◽  
Coherent Flow Structures ◽  
Highly Correlated ◽  
Naca 0012 ◽  
Proper Orthogonal

This study discusses a general framework to identify the unsteady features of a flow past an oscillating aerofoil in deep dynamic stall conditions. In particular, the work aims at demonstrating the advantages for the design process of the Spectral Proper Orthogonal Decomposition in accurately producing reliable reduced models of CFD systems and comparing this technique with standard snapshot-based models. Reynolds-Averaged Navier-Stokes system of equations, coupled with k−ω SST turbulence model, is used to produce the dataset, the latter consisting of a two-dimensional NACA 0012 aerofoil in the pitching motion. Modal analysis is performed on both velocity and pressure fields showing that, for vectored values, a proper tuning of the filtering process allows for better results compared to snapshot formulations and extract highly correlated coherent flow structures otherwise undetected. Wider filters, in particular, produce enhanced coherence without affecting the typical frequency response of the coupled modes. Conversely, the pressure field decomposition is drastically affected by the windowing properties. In conclusion, the low-order spectral reconstruction of the pressure field allows for an excellent prediction of aerodynamic loads. Moreover, the analysis shows that snapshot-based models better perform on the CFD values during the pitching cycle, while spectral-based methods better fit the loads’ fluctuations.

Numerical Studies on the Effect of Cambered Airfoil Blades on Self-Starting of Vertical Axis Wind Turbine Part 1: NACA 0012 and NACA 4415

2015 ◽  
Vol 787 ◽  
pp. 250-254 ◽  
Author(s):  
T. Micha Premkumar ◽  
Sivamani Seralathan ◽  
T. Mohan ◽  
N.N.P. Saran Reddy
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine Blades ◽  
Static Pressure Distribution ◽  
Numerical Studies ◽  
Airfoil Blades ◽  
Torque Values ◽  
Naca 0012

This is Part-1 of the two-part paper in considering the effect of cambered airfoil blades on self-starting of vertical axis wind turbine. Part 1 reports the numerical studies on self-starting of vertical axis wind turbine with comparative studies involving NACA 0012 and cambered airfoil NACA 4415. Part 2 of the paper deals with numerical studies of NACA 0018 and cambered air foil NACA 63415. Darrieus type VAWT is attracting many researchers attention for its inherent advantages and its diversified applications. However, a disadvantage is when the rotor is stationary, no net rotational forces arises, even at high-wind speed. The principal advantage of the vertical axis format is their ability to accept wind from any direction without yawing mechanism. However, self-starting capability is the major drawbacks. Moreover, literatures based on computational analysis involving the cambered airfoil are few only. The objective of this present study is to select the suitable airfoil blades on self-starting of VAWT at low-Reynolds number. The numerical studies are carried out to identify self-starting capability of the airfoil using CFD analysis by studying the flow field over the vertical axis wind turbine blades. The commercial CFD code, ANSYS CFX 13.0© was used for the present studies. Initially, the flow over NACA 0012 was simulated and analyzed for different angles of attacks and similarly carried out for NACA 4415. The contours of static pressure distribution and velocity as well as the force and torque were obtained. Even though the lift force for cambered airfoil NACA 4415 is higher, based on the torque values of the above blade profiles, asymmetrical airfoil NACA 0012 is found to be appropriate for self-starring of VAWT.

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