Papers by abolfazl abdolahi
Energy, 2022
Abstract Present work aims to enhance the aerodynamic performance of the three-part-blade (3-PB) ... more Abstract Present work aims to enhance the aerodynamic performance of the three-part-blade (3-PB) Vertical Axis Wind Turbine (VAWT) by setting a pitch angle using the solution of Reynolds averaged Navier-Stokes (RANS) equations in two and three dimensions. The 3-PB turbine with zero pitch angle is taken as the reference for comparison at wind speed of 7 m/s and tip speed ratios (TSRs) from 0.44 to 1.77. Having analyzed five pitch angles using 2D simulation, the best pitch angle of -2° is selected for 3D simulations. Flow characteristics and output torque of both 3-PB turbines with 0 and -2° pitch angles are scrutinized in 3D simulation. The blade with -2° pitch angle in the upwind area significantly contributes to the output torque, resulting in performance improvement for most TSRs. The modified turbine demonstrates the most improvement in average of total torque coefficient at TSR = 0.89, by 13.65%, while the maximum reduction in deviation of total torque coefficient from its average is 16.92% at TSR = 1.33. Based on the results, a delay of about 2° in azimuth angle has happened in dynamic stall phenomenon in the 3-PB turbine with -2° pitch angle. More details about flow structure are given in the paper.
Energy, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Journal of Wind Engineering and Industrial Aerodynamics
Energy for Sustainable Development
Journal of the Brazilian Society of Mechanical Sciences and Engineering
In the present work, airflow over blade section of helicopter rotor in forward flight is investig... more In the present work, airflow over blade section of helicopter rotor in forward flight is investigated numerically to offer a proposal for reduction or alleviation of dynamic stall on retreating blade. Unsteady 2-D compressible Reynolds-averaged Navier–Stokes equations are solved at flow conditions experienced by retreating blade of UH-60A helicopter rotor. For validation and verification purposes, flows around static and pitching airfoils in constant and variable flow Mach numbers are simulated and compared with other numerical results and experimental data. Having defined two deformation parameters, nine different permanently-deformed airfoils are produced from SSC-A09 airfoil. Flow field around these nine airfoils are simulated in variable flow Mach number with defined pitching angles. Coefficients of $$C_{{\text{l}}}$$ , $$C_{{\text{d}}}$$ and $$C_{{\text{m}}}$$ of these deformed SSC-A09 airfoils are compared with those of original airfoil to demonstrate that airfoil deformation proposed here is able to reduce and alleviate dynamic stall. Quantitatively, $$C_{{{\text{d}},\max }}$$ and absolute value of $$C_{{{\text{m}},\min }}$$ have been reduced up to 49.2% and 25%, respectively. In addition it is worth to mention that in some flow conditions dynamic stall is even eliminated with the proposed airfoil deformation. These are all achieved by permanent airfoil deformation which does not impose design complexities and expenses needed by dynamic airfoil deformation as proposed by others.
Energy, 2022
Abstract Present work aims to enhance the aerodynamic performance of the three-part-blade (3-PB) ... more Abstract Present work aims to enhance the aerodynamic performance of the three-part-blade (3-PB) Vertical Axis Wind Turbine (VAWT) by setting a pitch angle using the solution of Reynolds averaged Navier-Stokes (RANS) equations in two and three dimensions. The 3-PB turbine with zero pitch angle is taken as the reference for comparison at wind speed of 7 m/s and tip speed ratios (TSRs) from 0.44 to 1.77. Having analyzed five pitch angles using 2D simulation, the best pitch angle of -2° is selected for 3D simulations. Flow characteristics and output torque of both 3-PB turbines with 0 and -2° pitch angles are scrutinized in 3D simulation. The blade with -2° pitch angle in the upwind area significantly contributes to the output torque, resulting in performance improvement for most TSRs. The modified turbine demonstrates the most improvement in average of total torque coefficient at TSR = 0.89, by 13.65%, while the maximum reduction in deviation of total torque coefficient from its average is 16.92% at TSR = 1.33. Based on the results, a delay of about 2° in azimuth angle has happened in dynamic stall phenomenon in the 3-PB turbine with -2° pitch angle. More details about flow structure are given in the paper.
Energy, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Papers by abolfazl abdolahi