الفهرس 
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Abstract
Abstract
The effects of adding inner blades to the Bach-type Savonius turbine deserve extensive attention due to its promising improvement of the performance over the conventional turbine. In the present work, the performance improvement is based on comparing the power coefficient of two modified configurations are produced by adding concentric blades inside the original rotor blades to the conventional Savonius rotor. Numerical simulations are performed for three configurations: the traditional rotor, rotor with the additional inner blades tip parallel to the original rotor blades tip, and rotor with the additional inner blades parallel to the original rotor blades root. Numerical CFD analysis is carried out to study the influences of varying the radius and/or the central angle (β) of the additional inner blades applying ANSYS FLUENT. The considered radius of the additional blades ranges from 0.25 to 0.85 of that of the reference blade whereas β is varied from 70° to 180°. The obtained numerical results reveal that the performance of the rotor with additional inner blades of β=120° and radii ratio=0.55 is increased by 22.39%, 46.27%, and 103.86% when the tip speed ratio (TSR) equals 0.75, 0.25, and 1.3, respectively.
One-way fluid-structure interaction approach is considered to accomplish stress analysis of an Aluminum conventional and modified Savonius wind turbines through ANSYS STATIC STRUCTURAL to investigate the effects of the additional inner blades on the induced stress. It is found from the results that all of the investigated stresses -except normal stress- of the modified rotor of best configuration are greater than that of the conventional one. That requires more attention to the material and design of the rotor. Also, the change in all of studied stresses -except imported pressure load- versus the azimuth angles in case of the modified rotor is much lower than that of the conventional one. In addition, the azimuth angles of the maximum obtained values of all investigated parameters -except the imported pressure load- are not the same for the modified and conventional rotors.
Acknowledgments
In the name of Allah, the most gracious, the most merciful
First and foremost, countless thanks go to Allah for endowing me with health, patience, and knowledge to complete this work.
I acknowledge -with deep gratitude and appreciation- the inspiration, encouragement, valuable time and guidance provided to me at every stage of the research by my supervisors Prof. Dr. Yasser M. Shabana and Assoc. Prof. Dr. Khairy Elsayed Elsayed. Their immense knowledge and extensive experience have encouraged me in all the time of my academic research and daily life.
I also acknowledge the sincere and untiring efforts of Eng. Amr E. Saad El-Deen who assisted me during all stages of my simulations. I would like to express my gratitude for his valuable suggestions and help.
I also acknowledge the help and suggestions of Mr. Khaled M. Helal in correcting this thesis grammarly.
Best regards for Mr. Reda the secretary of the biofuel laboratory for his great effort and support throughout my study period.
Finally, massive thanks must also go to my beloved parents, wife, sisters and brother; without their continuous support, encouragement and love throughout my life, I would never have reached this stage in the first place.