Ali S. Alhamaly MECHANICAL ENGINEERING May 2018 KING FAHD UNIVERSITY OF PETROLEUM & MINERALS DHAHRAN- 31261, SAUDI ARABIA DEANSHIP OF GRADUATE STUDIES This thesis, written by Ali Salman Alhamaly under the direction of his thesis advisor and approved by his thesis committee, has been presented and accepted by the Dean of Graduate Studies, in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL ENGINEERING. ________________________ _______________________ Dr. Ahmet Sahin (Advisor) Dr. Zuhair M. Gasem Department Chairman ________________________ _______________________ Dr. Farooq Saeed (Member) Dr. Salam A. Zummo Dean of Graduate Studies _______________________ _______________________ Dr. Hassen Ouakad (Member) Date: © Ali S. Alhamaly 2018 iii Dedication This thesis is dedicated to my family who has continuously supported and encouraged me throughout my master program journey iv ACKNOWLEDGMENTS I would like to start by thanking my thesis committee members for their great effort, guidance, and contribution to this thesis. I would like to thank my advisor, Dr. Sahin for his guidance and encouragement throughout my research journey at KFUPM. I have definitely enjoyed the discussions we had both in class and out of class. I would like as well to thank Dr. Ouakad for his enthusiasm and kind words about my work and his kind words. I learned a lot from him during the short period of time that we get to know each other. Special thanks go to Dr. Saeed for his instrumental and influential role in this research. I would like to thank him for all time he has spent in developing the ideas that led to the framework of this research. I learned a lot of insights about the aerodynamics of vertical axis turbine throughout the numerous discussions we had during his time at KFUPM and latter at IAU. I certainly have enjoyed his mentorship throughout my graduate school time. The final thank goes to my family and close friends who have been a continuous source of encouragement to me during my graduate studies. They have given me the motivation to continue my endeavors in the research at toughest of times. v TABLE OF CONTENTS ACKNOWLEDGMENTS V TABLE OF CONTENTS VI LIST OF TABLES IX LIST OF FIGURES X LIST OF ABBREVIATIONS XIV ABSTRACT XV ةلاسرلا صخلم XVII CHAPTER 1 INTRODUCTION 1 CHAPTER 2 LITERATURE REVIEW 5 2.1 HAWT Optimization Studies 5 2.2 VAWT Optimization Studies 12 2.3 Lessons Learned from Previous Studies 19 CHAPTER 3 AERODYNAMIC AND STRUCTURAL ANALYSIS TOOLS FOR VAWT 22 3.1 Capabilities Desired in Analysis Codes 22 vi 3.2 Available Analysis Codes for VAWT 23 3.3 Aero-Servo-Elastic Code (HAWC2) 25 3.4 Beam Analysis Code (BECAS) 28 3.5 Optimizer and Data Analysis (MATLAB) 29 CHAPTER 4 TURBINE OPTIMIZATION FORMULATION 31 4.1 Problem Formulation 31 4.2 Objective Functions 33 4.3 Constraints 36 4.4 Design Variables 39 4.5 Optimization workflow 45 4.6 Optimization Cases 47 CHAPTER 5 RESULTS AND DISCUSSIONS 48 5.1 Description of the Reference Turbine 48 5.2 Comparison between Coupled and Sequential Optimization for 5 MW Turbine at 7.5 m/s Averaged Wind Speed 52 5.3 Comparison between VAWT Designs for High and Low Wind 79 5.4 Comparison between 2, 3.75, and 5 MW Designs 82 vii CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE RESEARCH 87 6.1 Conclusions 87 6.2 Recommendations for Future Research 90 REFERENCES 94 VITAE 98 viii LIST OF TABLES Table 4.1: Design variables used in coupled aerodynamic and structural optimization. ......... 40 Table 5.1: Main geometric properties of the DeepWind turbine. ............................................ 50 Table 5.2: Maximum power coefficient and corresponding TSR for reference and optimized turbines. .................................................................................................. 66 Table 5.3: location index and corresponding normalized blade length. .................................. 68 Table 5.4: maximum failure and the wind speed at maximum failure for several location along the blade length. ........................................................................................... 69 Table 5.5: Comparison between the reference and optimized turbines in the internal thickness of the blade material. ............................................................... 78 ix LIST OF FIGURES Figure 1.1: Comparison between VAWT and HAWT in off-shore applications and the cost implication of each configuration [5]. ................................................................... 3 Figure 3.1: The AC model representation of a 2D VAWT with the tangential (Qt) and normal (Qn) volumetric forces [55]. ................................................................... 26 Figure 3.2: discretization of a main body into several sub-bodies. Each sub-body consists of multiple Timoshenko beam elements [57]. ..................................................... 27 Figure 3.3: discretization of a VAWT ( left) and HAWT (right) in HAWC2 structural solver [57]. ........................................................................................................... 27 Figure 3.4: Example of using BECAS as a pre-processor for HAWC2 [26]. ......................... 29 Figure 3.5: Example of using BECAS to find the stress in the blade by applying the beam moments and forces that are computed from HAWC2 aeroelastic simulation [26]. ..................................................................................................................... 29 Figure 4.1: Weibull distribution with a shape parameter 𝒌 = 𝟐 and annual mean wind speed 𝑉 = 7.5 𝑚/𝑠 .............................................................................................. 35 Figure 4.2: Definition of material coordinate system used by BECAS [57]. .......................... 37 Figure 4.3: Example of a VAWT with stress analysis location designated by solid circle. The time series is for the flapwise bending moment in the blade. ...................... 38 Figure 4.4: Rotor outside shape for both DeepWind and modified Troposkien. Dotted lines show the locations of root sections. ..................................................................... 42 Figure 4.5: Blade airfoil internal thickness structure showing the material topology and the different zones of the structural design variables. ............................................... 43 Figure 4.6: Example of the blade mass per unit length distribution along the blade length. ... 44 Figure 4.7: Example of rotor speed variation with wind speed. .............................................. 44 x