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Wind Tunnel Analysis and Flight Test of a Wing Fence on a T-38

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Wind Tunnel Analysis and Flight Test of a Wing Fence on a T-38 Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 3-6-2009 Wind Tunnel Analysis and Flight Test of a Wing Fence on a T-38 Michael D. Williams Follow this and additional works at: https://scholar.afit.edu/etd Part of the Aerodynamics and Fluid Mechanics Commons Recommended Citation Williams, Michael D., "Wind Tunnel Analysis and Flight Test of a Wing Fence on a T-38" (2009). Theses and Dissertations. 2407. https://scholar.afit.edu/etd/2407 This Thesis is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. WIND TUNNEL ANALYSIS AND FLIGHT TEST OF A WING FENCE ON A T-38 THESIS Michael D. Williams, Major, USAF AFIT/GAE/ENY/09-M20 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED The views expressed in this thesis are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government. AFIT/GAE/ENY/09-M20 WIND TUNNEL ANALYSIS AND FLIGHT TEST OF A WING FENCE ON A T-38 THESIS Presented to the Faculty Department of Aeronautical and Astronautical Engineering Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Master of Science in Aeronautical Engineering Michael D. Williams, BS Major, USAF March 2009 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GAE/ENY/09-M20 WIND TUNNEL ANALYSIS AND FLIGHT TEST OF A WING FENCE ON A T-38 Michael D. Williams, BS Major, USAF Approved: //signed// 6 Mar 09 Dr. Mark F. Reeder, PhD (Chairman) Date //signed// 6 Mar 09 LtCol Christopher M. Shearer, PhD (Member) Date //signed// 6 Mar 09 LtCol Richard D. Branam, PhD (Member) Date AFIT/GAE/ENY/09-M20 Abstract A low-speed wind tunnel study and flight tests were performed to examine the effects of a wing fence on the T-38A. Wind tunnel results were based upon force and moment data collected with a six-component balance and flow visualization at Reynolds numbers up to 0.3 x 106, based on mean aerodynamic chord. The model did not include the last 7.79 feet of the aircraft, and the engine and exhaust were modeled as through- holes. Five fence geometries, placed at wing station 125 (±0.825 semispan), were compared. The best performer of these designs, based on drag polar, was the fence that wrapped the leading edge and extended 84.6 percent of the local chord length along the wing’s upper surface. Wind tunnel data showed that this fence increased the lift coefficient by up to 6.3 ± 0.6 percent and reduced spanwise and separated flow outboard the fence. The flight-tested fence was based on the best performing fence design from the wind tunnel study. The results were based on aircraft instrumentation and flow visualization at Reynolds numbers up to 9.98 x 106. It was inconclusive whether the fence caused an increase in lift coefficient. The fence reduced the roll-off tendency and wing rock during approaches to stall. Tuft visualization on the aircraft wing suggested that the fence reduced spanwise and separated flow outboard the fence, which agreed with the wind tunnel results. iv Acknowledgments I owe a great deal of gratitude to all those who supported me through this process. I would like to express my sincere appreciation to my faculty advisor, Dr. Mark Reeder, for his direction, help, and support throughout the course of this thesis effort. Additionally, I am extremely appreciative of Dr. Hugh Thornburg for helping me keep this project on time. His efforts were essential in completing the computer drawing work required to get the model printed and into the tunnel. Special thanks go to Rudy Johnson of AFRL/RBAI who supplied the original T-38 drawing data. Thanks to Jay Anderson, Chris Zickefoose, John Hixenbaugh, and LtCol Raymond Maple for their help along the way. Thanks to Roger Tanner with whom the idea originated. Thanks to team Ocho Lift from TPS class 08A for their efforts. Finally, a special thanks to my wife and family for their support and prayers throughout this process. Michael D. Williams v Table of Contents Page Abstract .............................................................................................................................. iv Acknowledgments................................................................................................................v Table of Contents ............................................................................................................... vi List of Figures .................................................................................................................... ix List of Tables ................................................................................................................... xix List of Symbols ..................................................................................................................xx I. Introduction .....................................................................................................................1 1.1 Background .........................................................................................................1 1.1.1 T-38 High Angle of Attack and Wing Characteristics.............................. 2 1.1.2 Flow Control. ........................................................................................... 5 1.1.3 Fence Success Stories............................................................................... 7 1.2 Problem Statement ..............................................................................................8 1.3 Research Focus ....................................................................................................9 II. Literature Review ..........................................................................................................13 2.1 Chapter Overview .............................................................................................13 2.2 Boundary Layer Theory ....................................................................................13 2.3 Stall....................................................................................................................16 2.4 Flow Control .....................................................................................................17 2.5 Wing Fences ......................................................................................................17 2.6 Results and Conclusions of Fence Tests from Research Documents................20 2.7 T-38 and Strakes................................................................................................23 2.8 Solfelt T-38 Wing Fence CFD Conclusions .....................................................25 2.9 Solfelt and Maple T-38 Wing Fence CFD Conclusions ...................................27 III. Methodology ................................................................................................................31 3.1 Chapter Overview .............................................................................................31 3.2 Model Construction and Printing ......................................................................31 3.2.1 Overview................................................................................................. 31 3.2.2 Model Mirror.......................................................................................... 33 3.2.3 Model Scaling. ........................................................................................ 34 3.2.4 Wind Tunnel Balance Mounting. ............................................................ 35 3.2.5 Incorporating the Ability to Change Model Configurations. ................. 39 3.2.6 Model Fence Building. ........................................................................... 42 3.2.7 3-D Printing. .......................................................................................... 44 3.3 Wind Tunnel Models .........................................................................................46 3.3.1 Overview................................................................................................. 46 3.3.2 Baseline and Fence Configurations. ...................................................... 46 3.3.3 Model Trip Tape. .................................................................................... 48 3.3.4 Model Tufts. ............................................................................................ 53 vi Page 3.3.5 Model - Fuselage Only. .......................................................................... 55 3.4 Experimental Equipment ...................................................................................55 3.4.1 AFIT Low-Speed Wind Tunnel. .............................................................. 55 3.4.2 AFIT 10 Pound Strain Gage Balance. ................................................... 59 3.5 Collecting and Processing Wind Tunnel Data ..................................................66 3.5.1 Correction of Balance Data Using MATLAB 10 Pound Balance Code. 66 3.5.2 Wind Tunnel Uncertainty Analysis. ........................................................ 70 3.6 Wind Tunnel Test Plan ......................................................................................72
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