University of Khartoum Faculty of Engineering Mechanical Engineering Department Numerical simulation of vortex trapped Airfoil A thesis submitted in partial fulfillment of the requirements for the degree of B.Sc. in Mechanical Engineering Presented by: Suhaib Salah El-Tayeb Awad Supervised by: Dr. Obai Younis Taha August 2015 ACKNOWLEDGEMENT I’m greatly indebted and thankful to Dr. Obai Younis Taha for her unlimited support, helpful instructions and closed supervision throughout the year. And also I want to thank prof.Mohammed Hashim Siddig for his great tips and helps. And I’d like to thank Dr.Ali Seory for the great CFD course and being very helpful. In addition great thank for Eng.Ahmed Alrayah hassan. Lastly for my brother Eng.Ammar Mohammed Ahmed For their technically support and advising. I DEDICATION To my lovely mother, Dear father, my brothers and sisters whom suffered very much till I have finished successfully my task. II ABSTRACT The main objective of this research is to study the characteristics of a smoothing section (airfoil) after work on (NACA23012). Vortex trapped is located in the front of the Airfoil section with depth of 50% on a round shape and circular vertical shape, research focused on the study of the influence of flow separation widget and vortex and bubbles formed and also the distribution of pressure at Airfoil Section for both laminated and turbulent flow cases. Also the lift and drag results from these adjustments are compared with the base type account. It was discussed according to results that taken from Application of Computation fluid dynamic ( CFD ). Research has been reached that the angular vortex trapped gives the highest value for the coefficient of lift while notes a rise in the value of the coefficient of drag it is imperative to conduct further studies to reduce the coefficient of drag. III الملخص ان الهدف اﻻساسى من هذا البحث هو دراسة خصائص المقطع اﻻنسيابى )الجنيح( بعد عمل قطعة على المقطع اﻻنسيابى اﻻساسى (NACA23012(. القطعة أجريت في الجزء اﻷمامي من المقطع اﻻنسيابي بعمق 50% على شكل دائري عمودي و دائري مائل, البحث ركز على دراسة تأثير القطعة على انفصال السريان والدومات المتكونة وايضا توزيع الضغط حول المقطع اﻻنسيابى المقطوع في حالتي السريان الصفائحي و المائر. حيث تم حساب الرفع والمقاومة الناتجة عن هذه التعديﻻت ومقارنتها مع النوع اﻻساسى. تمت مناقشة تأثيرات القطعة بناء على النتائج التى اخذت من برنامج تحسيب حركة الموائع عمليات (CFD( الذي تم استخدامه في عمليات التحسيب. من البحث تم الوصول الى ان القطعة الدائرية المائلة تعطي أعلى قيمة لمعامل الرفع بينما يﻻحظ وجود ارتفاع في قيمة معامل اﻻحتكاك لذا ﻻبد من اجراء المزيد من الدراسات لتقليل معامل اﻻحتكاك. IV TABLE OF CONTENTS ACKNOWLEDGEMENT ...................................................................................................................... I DEDICATION .................................................................................................................................... II ABSTRACT ....................................................................................................................................... III IV ............................................................................................................................................. الملخص TABLE OF CONTENTS ....................................................................................................................... V LIST OF ABBREVIATION AND SYMBOLS ......................................................................................... VII LIST OF FIGURES ........................................................................................................................... VIII LIST OF TABLES ................................................................................................................................ X Chapter One : INTRODUCTION ........................................................................................................ 1 1.1 DEFINITION: ............................................................................................................................. 2 1.2 CHARACTERISTICS OF THE AIRFOIL: .......................................................................................... 2 1.3 NACA SERIES: ........................................................................................................................... 3 1.4 Objective:................................................................................................................................... 9 Chapter Two : LITERATURE REVIEW .............................................................................................. 10 2.1 HISTORY AND DEVELOPMENT: ................................................................................................ 11 Chapter Three : METHODOLOGY................................................................................................... 19 3.1 Introduction to CFD: ................................................................................................................ 20 3.1.1 What is Computational Fluid Dynamics? .......................................................................... 20 3.1.2 The History of CFD ............................................................................................................ 20 3.2 How does a CFD code work? ................................................................................................... 21 3.2.1 Pre – processor ................................................................................................................. 22 3.2.2 Solver ................................................................................................................................ 24 3.2.3 Post – processor ............................................................................................................... 30 3.3 Governing Equations: .............................................................................................................. 31 3.3.1 Conservation of mass (Continuity Equation) .................................................................... 32 3.3.2 Conversion of momentum (Navier Stokes Equations ...................................................... 33 3.4 Turbulence Models .................................................................................................................. 34 V 3.4.1 RANS-based turbulence models ....................................................................................... 34 3.4.2 Two equation turbulence models .................................................................................... 35 3.4.3 The k equation .................................................................................................................. 35 3.4.4 The ℇ equation: ................................................................................................................ 35 Chapter Four : RESULTS ................................................................................................................. 37 4.1 Computational Domain ........................................................................................................... 38 4.2 Mesh Dependence Study: ....................................................................................................... 39 4.3 Final Results: ............................................................................................................................ 42 4.3.1 Pressure distributions for turbulent flow : ....................................................................... 42 4.3.2 Pressure distributions for laminar flow : .......................................................................... 46 4.3.3 Velocity Streamlines: ........................................................................................................ 48 4.3.3.1 Velocity Streamlines of turbulent flow: .................................................................... 48 4.3.3.2 Velocity Streamlines of laminar flow: ....................................................................... 50 4.3.3.3 Static Pressure: .......................................................................................................... 51 4.4 Lift and Drag Coefficients: ....................................................................................................... 55 4.4.1 Aerodynamic Coefficients tables: ..................................................................................... 55 4.4.1.1 Coefficients at turbulent flow: .................................................................................. 55 4.4.1.2 Coefficients at laminar flow: ..................................................................................... 56 4.4.2 Aerodynamic Coefficients Charts: .................................................................................... 57 4.4.2.1 Coefficients at turbulent flow: .................................................................................. 57 4.4.2.2 Coefficients at laminar flow: ..................................................................................... 59 Chapter Five : CONCLUSION AND RECOMMENDATIONS .............................................................. 61 5.1 Conclusion: .............................................................................................................................. 62 5.2 RECOMMENDATIONS: ............................................................................................................. 63 REFERENCES: ................................................................................................................................