Studying the Methods for Improving the Performance of Savonius Vertical Axis Wind Turbine
Ahmed Moustafa Sayed El kholy;
Abstract
The application of small scale wind turbines has been widely
spreading over the last decade. The vertical axis wind turbine (VAWT)
type is one class which is very attractive in this respect. The main
objective of the current thesis is to investigate methods of Savonius
turbine performance enhancement. It is suggested to use a downstream
baffle to achieve this goal. The flow field pattern around the Savonius
turbine is considered one of the most complex phenomena. This type of
fluid flow problems cannot be solved analytically. Computational Fluid
Dynamics (CFD) model is used to perform this task. The commercial
finite volume solver ANSYS-FLUENT 14.5 is used to solve transient
Reynolds Averaged Navier-Stokes (RANS) equations and turbulence
model equations. An accurate numerical model involves a wide range of
issues, from grid generation to turbulence modeling. These issues have
been addressed and the numerical results are compared with the available
experimental data from literature reported for the Savonius turbine
without baffle for model results validation. Accordingly, the developed
model is used to examine the Savonius turbine performance with the
baffle. The baffle parameters namely; position, length and inclination
angle are optimized using the generated model at a tip speed ratio of 0.8
and Re = 77600. The obtained numerical results for the turbine with
optimum baffle configuration shows that 34.4% increase of power
coefficient compared to that of without baffle. Moreover, the maximum
power coefficient reaches 0.3 at tip speed ratio of 1 which represents 41%
better improvement in power coefficient. The baffle effect is analyzed and
obtained results show that its major role is to accelerate the air flow
behind the advancing bucket thereby, reducing the pressure along its
backside. This effect enhances the positive driving torque on the
advancing bucket of the Savonius turbine and thus increases its power and
torque coefficients.
III
spreading over the last decade. The vertical axis wind turbine (VAWT)
type is one class which is very attractive in this respect. The main
objective of the current thesis is to investigate methods of Savonius
turbine performance enhancement. It is suggested to use a downstream
baffle to achieve this goal. The flow field pattern around the Savonius
turbine is considered one of the most complex phenomena. This type of
fluid flow problems cannot be solved analytically. Computational Fluid
Dynamics (CFD) model is used to perform this task. The commercial
finite volume solver ANSYS-FLUENT 14.5 is used to solve transient
Reynolds Averaged Navier-Stokes (RANS) equations and turbulence
model equations. An accurate numerical model involves a wide range of
issues, from grid generation to turbulence modeling. These issues have
been addressed and the numerical results are compared with the available
experimental data from literature reported for the Savonius turbine
without baffle for model results validation. Accordingly, the developed
model is used to examine the Savonius turbine performance with the
baffle. The baffle parameters namely; position, length and inclination
angle are optimized using the generated model at a tip speed ratio of 0.8
and Re = 77600. The obtained numerical results for the turbine with
optimum baffle configuration shows that 34.4% increase of power
coefficient compared to that of without baffle. Moreover, the maximum
power coefficient reaches 0.3 at tip speed ratio of 1 which represents 41%
better improvement in power coefficient. The baffle effect is analyzed and
obtained results show that its major role is to accelerate the air flow
behind the advancing bucket thereby, reducing the pressure along its
backside. This effect enhances the positive driving torque on the
advancing bucket of the Savonius turbine and thus increases its power and
torque coefficients.
III
Other data
| Title | Studying the Methods for Improving the Performance of Savonius Vertical Axis Wind Turbine | Other Titles | "دراسةتحسين اداء توربين الريــاح ذو المحور الرأسي (السافونيوس) | Authors | Ahmed Moustafa Sayed El kholy | Issue Date | 2015 |
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