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Ratna Kishore Velamati - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    Energies, 2021
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The energy crisis has forced researchers to look for various non-conventional energy sources. Wind energy is one of the potential sources, and researchers have invested resources in developing different kinds of wind turbines. Vertical axis wind turbines (VAWT) have received less attention than their horizontal-axis counterparts. A helical-bladed VAWT is preferred because it makes perfect sense as an improvement in design, as they have higher azimuth Angles of power generation capabilities. This paper studies the effects of the Helix Angle of blades in the aerodynamic performance of VAWT using 3D numerical simulations. Three different Helix Angles of 60°, 90°, and 120° of a three-bladed VAWT operating across different tip speed ratios were studied. Turbulence is modelled using a four-equation transition SST k-ω model (shear stress transport). The 60° helical-bladed VAWT was found to be better performing in comparison with all other helical-bladed and straight-bladed VAWT. The ripple effects on the shaft are also analysed using a standard deviation plot of the moment coefficient generated by a single blade over one complete cycle of its rotation. It was observed that the greater the Helix Angle, the lower the standard deviation. The paper also tries to analyse the percentage of power generated by each quartile of flow and the contribution of each section of the blade. Ansys FLUENT was employed for the entire study. A comparative study between different helical-bladed VAWT and straight-bladed VAWT was carried out along with wake structure analysis and flow contours for a better understanding of the flow field.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    2020
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The global energy crisis has lead researchers explore other sources of energy like wind, resulting in a wide acceptance of wind turbines. Vertical axis wind turbines (VAWT) more suitable for small scale application in urban conditions than their horizontal-axis counterparts. A Helical bladed VAWT would reduce the ripple effect when compared to Straight bladed VAWT. The effect of the blade Helix Angle on the aerodynamic performance of VAWT using 3D numerical simulations is studied. Turbulence modelled using 4-Equation transition SST k-w model. Three different Helix Angles of 60, 90 and 120 of a 3 bladed VAWT operating across different tip speed ratios were studied. The 60 helical bladed VAWT was found to perform better than all other helical bladed and straight bladed VAWT. Standard deviation of the moment coefficient generated by a blade plotted against 360 of azimuth rotation revealed that the ripple effect on the shaft produced by cyclic loading of the straight blade is considerably reduced upon introduction of Helix Angle, with 120 helical blade giving lowest standard deviation. The analysis has been done for the percentage of power generated by each quartile of flow and the contribution of each section of the blade. A comparative study was also conducted between different helical bladed VAWT and straight bladed VAWT. Flow feature analysis also revealed the reasons behind secondary peaks and the performance improvement when tip speed ratio increases. Wake structure analysis and flow contours were also studied for a better understanding of the flow field.

Unnikrishnan Divakaran - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    Energies, 2021
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The energy crisis has forced researchers to look for various non-conventional energy sources. Wind energy is one of the potential sources, and researchers have invested resources in developing different kinds of wind turbines. Vertical axis wind turbines (VAWT) have received less attention than their horizontal-axis counterparts. A helical-bladed VAWT is preferred because it makes perfect sense as an improvement in design, as they have higher azimuth Angles of power generation capabilities. This paper studies the effects of the Helix Angle of blades in the aerodynamic performance of VAWT using 3D numerical simulations. Three different Helix Angles of 60°, 90°, and 120° of a three-bladed VAWT operating across different tip speed ratios were studied. Turbulence is modelled using a four-equation transition SST k-ω model (shear stress transport). The 60° helical-bladed VAWT was found to be better performing in comparison with all other helical-bladed and straight-bladed VAWT. The ripple effects on the shaft are also analysed using a standard deviation plot of the moment coefficient generated by a single blade over one complete cycle of its rotation. It was observed that the greater the Helix Angle, the lower the standard deviation. The paper also tries to analyse the percentage of power generated by each quartile of flow and the contribution of each section of the blade. Ansys FLUENT was employed for the entire study. A comparative study between different helical-bladed VAWT and straight-bladed VAWT was carried out along with wake structure analysis and flow contours for a better understanding of the flow field.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    2020
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The global energy crisis has lead researchers explore other sources of energy like wind, resulting in a wide acceptance of wind turbines. Vertical axis wind turbines (VAWT) more suitable for small scale application in urban conditions than their horizontal-axis counterparts. A Helical bladed VAWT would reduce the ripple effect when compared to Straight bladed VAWT. The effect of the blade Helix Angle on the aerodynamic performance of VAWT using 3D numerical simulations is studied. Turbulence modelled using 4-Equation transition SST k-w model. Three different Helix Angles of 60, 90 and 120 of a 3 bladed VAWT operating across different tip speed ratios were studied. The 60 helical bladed VAWT was found to perform better than all other helical bladed and straight bladed VAWT. Standard deviation of the moment coefficient generated by a blade plotted against 360 of azimuth rotation revealed that the ripple effect on the shaft produced by cyclic loading of the straight blade is considerably reduced upon introduction of Helix Angle, with 120 helical blade giving lowest standard deviation. The analysis has been done for the percentage of power generated by each quartile of flow and the contribution of each section of the blade. A comparative study was also conducted between different helical bladed VAWT and straight bladed VAWT. Flow feature analysis also revealed the reasons behind secondary peaks and the performance improvement when tip speed ratio increases. Wake structure analysis and flow contours were also studied for a better understanding of the flow field.

Akram Mohammad - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    Energies, 2021
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The energy crisis has forced researchers to look for various non-conventional energy sources. Wind energy is one of the potential sources, and researchers have invested resources in developing different kinds of wind turbines. Vertical axis wind turbines (VAWT) have received less attention than their horizontal-axis counterparts. A helical-bladed VAWT is preferred because it makes perfect sense as an improvement in design, as they have higher azimuth Angles of power generation capabilities. This paper studies the effects of the Helix Angle of blades in the aerodynamic performance of VAWT using 3D numerical simulations. Three different Helix Angles of 60°, 90°, and 120° of a three-bladed VAWT operating across different tip speed ratios were studied. Turbulence is modelled using a four-equation transition SST k-ω model (shear stress transport). The 60° helical-bladed VAWT was found to be better performing in comparison with all other helical-bladed and straight-bladed VAWT. The ripple effects on the shaft are also analysed using a standard deviation plot of the moment coefficient generated by a single blade over one complete cycle of its rotation. It was observed that the greater the Helix Angle, the lower the standard deviation. The paper also tries to analyse the percentage of power generated by each quartile of flow and the contribution of each section of the blade. Ansys FLUENT was employed for the entire study. A comparative study between different helical-bladed VAWT and straight-bladed VAWT was carried out along with wake structure analysis and flow contours for a better understanding of the flow field.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    2020
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The global energy crisis has lead researchers explore other sources of energy like wind, resulting in a wide acceptance of wind turbines. Vertical axis wind turbines (VAWT) more suitable for small scale application in urban conditions than their horizontal-axis counterparts. A Helical bladed VAWT would reduce the ripple effect when compared to Straight bladed VAWT. The effect of the blade Helix Angle on the aerodynamic performance of VAWT using 3D numerical simulations is studied. Turbulence modelled using 4-Equation transition SST k-w model. Three different Helix Angles of 60, 90 and 120 of a 3 bladed VAWT operating across different tip speed ratios were studied. The 60 helical bladed VAWT was found to perform better than all other helical bladed and straight bladed VAWT. Standard deviation of the moment coefficient generated by a blade plotted against 360 of azimuth rotation revealed that the ripple effect on the shaft produced by cyclic loading of the straight blade is considerably reduced upon introduction of Helix Angle, with 120 helical blade giving lowest standard deviation. The analysis has been done for the percentage of power generated by each quartile of flow and the contribution of each section of the blade. A comparative study was also conducted between different helical bladed VAWT and straight bladed VAWT. Flow feature analysis also revealed the reasons behind secondary peaks and the performance improvement when tip speed ratio increases. Wake structure analysis and flow contours were also studied for a better understanding of the flow field.

Ajith Ramesh - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    Energies, 2021
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The energy crisis has forced researchers to look for various non-conventional energy sources. Wind energy is one of the potential sources, and researchers have invested resources in developing different kinds of wind turbines. Vertical axis wind turbines (VAWT) have received less attention than their horizontal-axis counterparts. A helical-bladed VAWT is preferred because it makes perfect sense as an improvement in design, as they have higher azimuth Angles of power generation capabilities. This paper studies the effects of the Helix Angle of blades in the aerodynamic performance of VAWT using 3D numerical simulations. Three different Helix Angles of 60°, 90°, and 120° of a three-bladed VAWT operating across different tip speed ratios were studied. Turbulence is modelled using a four-equation transition SST k-ω model (shear stress transport). The 60° helical-bladed VAWT was found to be better performing in comparison with all other helical-bladed and straight-bladed VAWT. The ripple effects on the shaft are also analysed using a standard deviation plot of the moment coefficient generated by a single blade over one complete cycle of its rotation. It was observed that the greater the Helix Angle, the lower the standard deviation. The paper also tries to analyse the percentage of power generated by each quartile of flow and the contribution of each section of the blade. Ansys FLUENT was employed for the entire study. A comparative study between different helical-bladed VAWT and straight-bladed VAWT was carried out along with wake structure analysis and flow contours for a better understanding of the flow field.

  • Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine
    2020
    Co-Authors: Unnikrishnan Divakaran, Ajith Ramesh, Akram Mohammad, Ratna Kishore Velamati
    Abstract:

    The global energy crisis has lead researchers explore other sources of energy like wind, resulting in a wide acceptance of wind turbines. Vertical axis wind turbines (VAWT) more suitable for small scale application in urban conditions than their horizontal-axis counterparts. A Helical bladed VAWT would reduce the ripple effect when compared to Straight bladed VAWT. The effect of the blade Helix Angle on the aerodynamic performance of VAWT using 3D numerical simulations is studied. Turbulence modelled using 4-Equation transition SST k-w model. Three different Helix Angles of 60, 90 and 120 of a 3 bladed VAWT operating across different tip speed ratios were studied. The 60 helical bladed VAWT was found to perform better than all other helical bladed and straight bladed VAWT. Standard deviation of the moment coefficient generated by a blade plotted against 360 of azimuth rotation revealed that the ripple effect on the shaft produced by cyclic loading of the straight blade is considerably reduced upon introduction of Helix Angle, with 120 helical blade giving lowest standard deviation. The analysis has been done for the percentage of power generated by each quartile of flow and the contribution of each section of the blade. A comparative study was also conducted between different helical bladed VAWT and straight bladed VAWT. Flow feature analysis also revealed the reasons behind secondary peaks and the performance improvement when tip speed ratio increases. Wake structure analysis and flow contours were also studied for a better understanding of the flow field.

Zesen Nie - One of the best experts on this subject based on the ideXlab platform.

  • Experimental study of effects of baffle Helix Angle on shell-side performance of shell-and-tube heat exchangers with discontinuous helical baffles
    Experimental Thermal and Fluid Science, 2015
    Co-Authors: Bin Gao, Zesen Nie
    Abstract:

    Abstract Flow resistance and heat transfer of several shell-and-tube heat exchangers with discontinuous helical baffles are experimentally studied and compared at the five Helix Angles of 8°, 12°, 20°, 30° and 40°. The second-law based thermodynamic analysis is employed to analyze the effects of baffle Helix Angle on the irreversible loss of heat exchangers. The results indicate that the shell-side pressure drop and heat transfer coefficient of the heat exchanger with smaller Helix Angle are higher than those with larger Helix Angle at a given shell-side volume flow rate. However, in the condition of the same shell-side Reynolds number, the flow resistance with larger Helix Angle is lower and the heat transfer performance is better. The heat exchanger with helical baffles at 40° Helix Angle presents the best comprehensive performance among the five testing heat exchangers. In the second-law thermodynamic comparisons, the irreversibility of heat exchanger is estimated by the theories of entropy generation and entransy dissipation. Experimental analysis shows that in the same heat transfer area and under the same working conditions, the shell-and-tube heat exchanger with smaller Helix Angle baffles produces less irreversibility in the heat exchange process. In addition, the heat exchangers with helical baffles are more effective under certain conditions of low shell-side Reynolds number.