DOCSLIB.ORG

Overview of Laminar Flow Control

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Overview of Laminar Flow Control NASA/TP-1998-208705 Overview of Laminar Flow Control Ronald D. Joslin Langley Research Center, Hampton, Virginia National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23681-2199 October 1998 Acknowledgment.,; The author's only intent in generating this overview was to summarize the available literature from a historical prospective while making no judgement on the value of any contribution. This publication is dedicated to the many scientists, engineers, and managers who have devoted a portion of their careers toward developing technologies which would someday lead to aircraft with laminar flow. Special thanks to Anna Ruzecki and Dee Bullock for graphics services which led to the reproduced figures, Eloise Johnson for technical editing services, and Patricia Gottschali for typesetting services. Gratitude is expressed to the following companies and reviewers of this manuscript or a portion of this manuscript: Scott G. Anders, Dennis M. Bushnell, Michael C. Fischer, Jerry N. Hefner, Dal V. Maddalon, William L. Sellers III, Richard A. Thompson, and Michael J. Walsh, Langley Research Center; Paul Johnson and Jeff Crouch, The Boeing Company; E. Kevin Hertzler, Lockheed Martin Corporation; and Feng Jiang, McDonnell Douglas Corporation. The use of trademarks or names of manufacturers in this report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or _nanufacturers by the National Aeronautics and Space Administration. Available from the following: NASA Center for AeroSpace Information (CASI) National Technical Information Service (NTIS) 7121 Standard Drive 5285 Port Royal Road Hanover, MD 21076-1320 Springfield, VA 22161-2171 (301) 621-0390 (703) 487-465O Contents Tables ............................................................................ v Figures ........................................................................... v Abbreviations and Symbols ........................................................... ix 1. Introduction ..................................................................... 1 2. Background ...................................................................... 2 2.1. Definition of LFC .............................................................. 2 2.2. Benefits of LFC ............................................................... 3 3. Laminar Flow Control Design Methodology ............................................ 6 3.1. Boundary-Layer Instability Issues ................................................. 6 3.2. Surface Tolerances for Laminar Flow .............................................. 9 3.2.1. Waviness ................................................................ 12 3.2.2. Two-Dimensional Surface Discontinuities ...................................... 13 3.2.3. Three-Dimensional Surface Discontinuities ..................................... 13 3.3. Critical Suction Parameters for LFC .............................................. 14 3.4. Manufacturing Issues .......................................................... 16 3.4.1. Joints ................................................................... 16 3.4.2. Holes ................................................................... 16 3.5. Transition Prediction Design Tool Methodology .................................... 17 3.5.1. Granville Criterion ......................................................... 18 3.5.2. C1 and C2 Criteria ......................................................... 18 3.5.3. Linear Stability Theory ..................................................... 18 3.5.4. Parabolized Stability Equations Theory ......................................... 23 3.5.5. Transition Prediction Coupled to Turbulence Modeling ............................ 24 3.5.6. Receptivity--The Ingestion of Disturbances ..................................... 24 3.5.7. Optimize Linear Design for LFC .............................................. 25 3.5.8. Thermal LFC ............................................................. 26 3.5.9. Advanced Prediction of Manufacturing Tolerances ............................... 26 4. Laminar Flow Control Aircraft Operations ............................................ 26 4.1. Insect Contamination .......................................................... 27 4.1.1. Paper Cover ................................................................ 29 4.1.2. Scrapers ................................................................. 30 4.1.3. Deflectors ................................................................ 30 4.1.4. Fluidic Cover ............................................................. 30 4.1.5. Thermal Cover ............................................................ 30 4.1.6. Relaminarization .......................................................... 30 4.1.7. Liquid Discharge .......................................................... 31 4.1.8. Flexible Surface or Cover ................................................... 31 4.2. Ice Accumulation and Atmospheric Particulates .................................... 32 4.2.1. Ice Accumulation .......................................................... 32 4.2.2. Atmospheric Particulates .................................................... 33 4.3. Boundary-Layer Control for Takeoff and Landing ................................... 33 4.4. Operational Maintenance of Laminar Flow ......................................... 34 .oo !!1 5. Laminar Flow Control Prior to OPEC Oil Embargo ..................................... 35 5.1. B- 18 Slot-Suction Glove Flight Test (1941 ) ........................................ 35 5.2. LFC Wind Tunnel Tests (1949-1963) ............................................. 36 5.2.1. Wind Tunnel Test With Porous Bronze Airfoil .................................. 36 5.2.2. University of Michigan Slot-Suction Wind Tunnel Tests ........................... 36 5.2.3. Douglas Slot-Suction Wind Tunnel Test ....................................... 37 5.3. Anson Mk. 1 Porous-Suction Flight Test (1948-1950) ............................... 37 5.4. Vampire Porous-Suction Flight Test (1953-1954) ................................... 37 5.5. F-94A Slot-Suction Glove Flight Test (1953-1956) ................................. 38 5.6. Later Subsonic Slot-Suction Wind Tunnel Tests (1958) .............................. 40 5.7. Supersonic Slot-Suction Wind Tunnel Tests (1957-1965) ............................. 41 5.8. X-21A (WB-66) Slot-Suction Flight Test (1960-1965) ............................... 43 6. Laminar Flow Control After OPEC Oil Embargo ....................................... 45 6.1. Boeing Research Wind Tunnel LFC Test (1977-1978) ................................ 46 6.2. Langley 8-Foot Transonic Pressure Tunnel LFC Wind Tunnel Test (1981-1988) ........... 46 6.3. Jetstar Leading-Edge Flight Test (1983-1986) ...................................... 48 6.4. Cessna Citation HI Nacelle LFC Flight Test (1986) .................................. 49 6.5. Dassault Falcon 50 HLFC Flight Tests (1987-1990) ................................. 50 6.6. Boeing 757 HLFC Flight Test (1990-1991) ........................................ 51 6.7. HLFC ONERA-CERT T2 Wind Tunnel Test (1991) ................................. 52 6.8. HLFC Nacelle Demonstration Flight Test (1992) .................................... 53 6.9. NLF and LFC Nacelle Wind Tunnel Tests (1991-1993) ............................... 53 6.10. VFW 614 HLFC Transonic Wind Tunnel Test (1992) ............................... 54 6.11. European NLF and HLFC Nacelle Demonstrator Flighl Tests (1992-1993) .............. 54 6.12. A320 Laminar Fin Wind Tunnel and Flight Test Progrzm (1993-1998) ................. 55 6.13. Langley 8-Foot Transonic Pressure Tunnel HLFC Wind Tunnel Test (1993-1995) ........ 55 6.14. High-Speed Civil Transport (1986) .............................................. 56 6.15. Supersonic LFC Quiet-Tunnel Tests (1987-1996) .................................. 57 6.16. F- 16XL Supersonic LFC Flight Tests (1989-1996) ................................. 58 7. Concluding Remarks ............................................................. 60 Appendix A---Subsonic Natural Laminar Flow Research ................................... 62 Appendix B--Supersonic Natural Laminar Flow Research ................................. 66 References ....................................................................... 67 Tables ........................................................................... 81 Figures .......................................................................... 84 iv Tables Table 1. Subsonic and Transonic LFC Wind Tunnel and Flight Experiments and Major Accomplishments ................................................................ 81 Table 2. Subsonic LFC Wind Tunnel and Flight Experiments and Major Accomplishments Prior to OPEC Oil Embargo (1970) .................................................. 82 Table 3. LFC Wind Tunnel and Flight Experiments and Major Accomplishments After OPEC Oil Embargo ............................................................... 83 Figures Figure 1• Overview of Laminar Flow Control Projects ..................................... 84 Figure 2. Concepts and practical application ............................................. 85 Figure 3. Aircraft drag breakdown ..................................................... 86 Figure 4. Predicted drag benefits of laminar flow on subsonic business jet ..................... 86 Figure 5. Benefits of LFC with range for subsonic aircraft
Load more

Recommended publications
  • Blowing and Suction Flow Separation Control Over NACA 0012 Airfoil
    Journal of Mechanical Science and Technology 28 (4) (2014) 1297~1310 www.springerlink.com/content/1738-494x DOI 10.1007/s12206-014-0119-1 Numerical study of blowing and suction slot geometry optimization on NACA 0012 airfoil† Kianoosh Yousefi*, Reza Saleh and Peyman Zahedi Department of Mechanical Engineering, College of Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran (Manuscript Received March 1, 2013; Revised July 10, 2013; Accepted November 9, 2013) ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Abstract The effects of jet width on blowing and suction flow control were evaluated for a NACA 0012 airfoil. RANS equations were em- ployed in conjunction with a Menter’s shear stress turbulent model. Tangential and perpendicular blowing at the trailing edge and per- pendicular suction at the leading edge were applied on the airfoil upper surface. The jet widths were varied from 1.5% to 4% of the chord length, and the jet velocity was 0.3 and 0.5 of the free-stream velocity. Results of this study demonstrated that when the blowing jet width increases, the lift-to-drag ratio rises continuously in tangential blowing and decreases quasi-linearly in perpendicular blowing. The jet widths of 3.5% and 4% of the chord length are the most effective amounts for tangential blowing, and smaller jet
    [Show full text]
  • Laminar How Control (1976- 1982)
    NASA T" 84496 NASATechnical Memomdm 844% c.1 Laminar How Control (1976-1982) A Selected, Annotated Bibliography Marie H. Tuttle and Dal V. Maddalon AUGUST 1982 " . .. - " NASA NASATechnical Memorandm -% Laminar flow Control (1976-1982) A Selected, Annotated Bibliography Marie H. Tuttle and Dal V. Maddalon Langley Research Center Hampton, Virginia National Aeronautics and Space Administration Scientlflc and Technlcal Information Branch \. i ” INTRODUCTION .................................................................... 1 BIBLIOGRAPHY (1976-1982) ........................................................ 3 APPENDIX ........................................................................ 65 ENTRIES WITH PUBLICATIONDATES PRIOR TO 1976 .................................... 66 AUTHOR INDEX .................................................................... 76 iii INTRODUCTION Laminar Flow Control (LFC) technologydevelopment has undergone tremendous progress in recent years as focused research efforts in materials, aerodynamics, systems,and structures have begun to pay off. A virtualexplosion in the number of research papers published on this subject has occurred since interest was first stimulated by the 1976 introduction of the NASA's Aircraft EnergyEfficiency Laminar Flow Control (ACEE/LFC) Program.Today, a wide variety of fundamentaland applied researchprograms exist, not only in controlled (active) boundary-layer flow, but alsoin natural (passive) laminar flow. Studies of airfoils whichcombine the two methods (hybrid) are now beginning.
    [Show full text]
  • An Aerodynamic Model for Vane-Type Vortex Generators. In
    Poole, D. , Bevan, R., Allen, C., & Rendall, T. (2016). An Aerodynamic Model for Vane-Type Vortex Generators. In 8th AIAA Flow Control Conference (AVIATION2016) [AIAA 2016-4085] American Institute of Aeronautics and Astronautics Inc. (AIAA). https://doi.org/10.2514/6.2016-4085 Peer reviewed version Link to published version (if available): 10.2514/6.2016-4085 Link to publication record in Explore Bristol Research PDF-document This is the author accepted manuscript (AAM). The final published version (version of record) is available online via AIAA at http://arc.aiaa.org/doi/10.2514/6.2016-4085. Please refer to any applicable terms of use of the publisher. University of Bristol - Explore Bristol Research General rights This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/red/research-policy/pure/user-guides/ebr-terms/ An Aerodynamic Model for Vane-Type Vortex Generators D.J. Poole ,∗ R.L.T. Bevan ,y C.B. Allen ,z T.C.S. Rendallx Department of Aerospace Engineering, University of Bristol, Bristol, BS8 1TR, U.K. A new, physics-based model is presented for flows around vortex generators. The model uses a modified lifting-line method with added physics to account for boundary layer flow. The lifting-line method is extended to also include a vortex lift component and these two components are used to calculate the strength of a vortex shed from an isolated vortex gen- erator. The circulation model is developed further to be used within a CFD framework in a source term approach.
    [Show full text]
  • Slot Suction of the Turbulent Boundary Layer an Experimental Study
    Slot Suction of the Turbulent Boundary Layer An Experimental Study Tim van der Hoeven March 28, 2013 Faculty of Aerospace Engineering ⋅ Delft University of Technology Slot Suction of the Turbulent Boundary Layer An Experimental Study Master of Science Thesis For obtaining the degree of Master of Science in Aerospace Engineering at Delft University of Technology Tim van der Hoeven March 28, 2013 Faculty of Aerospace Engineering ⋅ Delft University of Technology Copyright © Tim van der Hoeven All rights reserved. Delft University Of Technology Department Of Aerodynamics The undersigned hereby certify that they have read and recommend to the Faculty of Aerospace Engineering for acceptance a thesis entitled \Slot Suction of the Turbulent Boundary Layer" by Tim van der Hoeven in partial fulfillment of the requirements for the degree of Master of Science. Dated: March 28, 2013 Head of department: Prof. Dr. Ir. F. Scarano Supervisor: Dr. Ir. L.L.M. Veldhuis Reader: Dr. Ir. B.W. van Oudheusden Reader: Ir. E. Terry Reader: Dr. Ir. D. Ragni Abstract This study examines the effects of slot suction on the mean characteristics of a two-dimensional turbulent boundary layer. Previous studies on this subject have mainly focused on low Reynolds number boundary layers (i.e. Reθ ≤ 2,000). Furthermore, numerical tools are often not able to accurately predict the effects of slot suction. To grasp the effects of slot suction at conditions more relevant to engineering problems, the present research focuses on a turbulent boundary layer with a Reynolds number of Reθ ≈ 10,000. An experimental investigation has been conducted in the W-tunnel facility at the Delft Univer- sity of Technology.
    [Show full text]
  • Three-Dimensional Suction Flow Control and Suction Jet Length Optimization of NACA 0012 Wing Kianoosh Yousefi, Reza Saleh
    Three-dimensional suction flow control and suction jet length optimization of NACA 0012 wing Kianoosh Yousefi, Reza Saleh To cite this version: Kianoosh Yousefi, Reza Saleh. Three-dimensional suction flow control and suction jet length optimiza- tion of NACA 0012 wing. Meccanica, Springer Verlag, 2015, 50 (6), pp.1481-1494. 10.1007/s11012- 015-0100-9. hal-01590679 HAL Id: hal-01590679 https://hal.archives-ouvertes.fr/hal-01590679 Submitted on 23 Sep 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Meccanica DOI 10.1007/s11012-015-0100-9 3 Three-dimensional suction flow control and suction jet 4 length optimization of NACA 0012 wing 5 Kianoosh Yousefi • Reza Saleh Author Proof 6 Received: 8 December 2013 / Accepted: 8 January 2015 7 Ó Springer Science+Business Media Dordrecht 2015 8 Abstract A three-dimensional suction flow control with center suction than with tip suction. Ultimately, 31 9 study was performed to investigate the aerodynamic when the jet length is less than half the wingspan, tip 32 10 characteristics of a rectangular wing with a NACA suction is the better of the two alternatives, and when 33 11 0012 airfoil section.
    [Show full text]
  • A History of Suction-Type Laminar-Flow Control with Emphasis on Flight Research
    MONOGRAPHS IN AEROSPACE HISTORY #13 A History of Suction-Type Laminar-Flow Control with Emphasis on Flight Research by Albert L. Braslow i A History of Suction-Type Laminar-Flow Control with Empahsis on Flight Research by Albert L. Braslow NASA History Division Office of Policy and Plans NASA Headquarters Washington, DC 20546 Monographs in Aerospace History Number 13 1999 ii Table of Contents Foreword.........................................................................................................................iv Preface .............................................................................................................................v Laminar-Flow Control Concepts and Scope of Monograph ...........................................1 Early Research on Suction-Type Laminar-Flow Control Research from the 1930s through the War Years ......................................................3 Research from after World War II to the Mid-1960s ................................................5 Post X-21 Research on Suction-Type Laminar-Flow Control Hiatus in Research ..................................................................................................13 Resumption of Research .........................................................................................13 Research from the Mid-1970s to the Mid-1990s ....................................................16 Natural Laminar Flow (NLF) on Swept Wings: F-111/TACT and F-14 .....................17 Noise: Boeing 757...................................................................................................18
    [Show full text]
  • Drag Reduction by Laminar Flow Control
    energies Article Drag Reduction by Laminar Flow Control Nils Beck 1,*, Tim Landa 2, Arne Seitz 3, Loek Boermans 4, Yaolong Liu 1 ID and Rolf Radespiel 2 1 Aeronautics Research Center Niedersachsen (NFL), TU Braunschweig, Hermann-Blenk-Straße 27, 38108 Braunschweig, Germany; [email protected] 2 Institute of Fluid Mechanics (ISM), TU Braunschweig, Hermann-Blenk-Straße 37, 38108 Braunschweig, Germany; [email protected] (T.L.); [email protected] (R.R.) 3 Institute of Aerodynamics and Flow Technology (DLR-AS), German Aerospace Center, Lilienthalplatz 7, 38108 Braunschweig, Germany; [email protected] 4 Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands; [email protected] * Correspondence: [email protected]; Tel.: +49-531-391-66662 Received: 20 December 2017; Accepted: 15 January 2018; Published: 20 January 2018 Abstract: The Energy System Transition in Aviation research project of the Aeronautics Research Center Niedersachsen (NFL) searches for potentially game-changing technologies to reduce the carbon footprint of aviation by promoting and enabling new propulsion and drag reduction technologies. The greatest potential for aerodynamic drag reduction is seen in laminar flow control by boundary layer suction. While most of the research so far has been on partial laminarization by application of Natural Laminar Flow (NLF) and Hybrid Laminar Flow Control (HLFC) to wings, complete laminarization of wings, tails and fuselages promises much higher gains. The potential drag reduction and suction requirements, including the necessary compressor power, are calculated on component level using a flow solver with viscid/inviscid coupling and a 3D Reynolds-Averaged Navier-Stokes (RANS) solver.
    [Show full text]
  • High-Lift Research for Future Transport Aircraft
    HIGH-LIFT RESEARCH FOR FUTURE TRANSPORT AIRCRAFT R. Radespiel, W. Heinze, L. Bertsch, Technische Universität Braunschweig, Hermann-Blenk-Str. 37, 38108 Braunschweig, Germany Abstract Careful analysis of long-term objectives of air transport indicates that the needed progress in vehicle perfor- mance cannot be achieved by following the current, evolutionary technology development. Particular exam- ples are noise reduction and high-lift performance at take-off and landing. The long-term objectives call for research on the fundamentals for a new segment of commercial low-noise transport aircraft with short take- off and landing capability, which allows a much better integration into the metropolitan areas of the industrial- ised society. Such research is in the focus of the Collaborative Research Centre CRC 880. The Centre aims at drastic reductions of airframe noise by developing the fundamentals of noise reducing surfaces in aero- acoustic and aerodynamic design. A promising approach towards reducing engine noise shields the noise by suited configuration design. Improving the efficiency of active high lift requires reducing the flow actuation power. For this objective the benefits of form-variable leading edges, by exploiting the synergies of suction and blowing in active high-lift flaps with spanwisely distributed compressor units, and finally the potentials of dynamic flow control are explored. The advances obtained in noise reductions and in effective high-lift tech- nologies are assessed using fully iterated aircraft designs. The Centre also seeks new knowledge on the dynamic behaviour of aircraft with active high lift during flight in the atmospheric boundary layer. Therefore, the flight mechanics of critical landing manoeuvers is analysed along with exploring the fundamentals of un- steady flow around active high-lift wings and the aero-elastic reactions of the wing structure on flight loads.
    [Show full text]
  • Investigation of Boundary Layer Suction on a Wind Turbine Airfoil Using CFD
    Author: Apostolos Tentolouris Piperas Investigation of Boundary Layer Suction on a Wind Turbine Airfoil using CFD Supervisor: Martin O.L. Hansen Wind Energy Building 403 Kongens Lyngby Master’s Thesis 5th August 2010 Acknowledgements There is not much to acknowledge really. People without whom I would never have survived my studies and who helped me realize that there is plenty of beauty to be shared despite the smothering workload of these past two years, a period that eventually lead to the present document, do not need this page to be aware of it and most likely will never read it in the first place. I would like however to express my gratitude to my supervisor Martin O.L. Hansen, probably the smartest person on the planet, for taking the time to bother with me and my questions, and Dalibor Cavar with Juan Pablo Murcia without whom my work would have taken twice the time and effort. Finally, I would like to thank whoever was responsible for my admittance to DTU. I may not have become a better engineer in the direction I was hoping, but I ended up becoming a better person, which is something I could have never hoped for. i Preface This report is part of the requirements to achieve the Master of Science in Engineering (M.Sc.Eng.) at the Technical University of Denmark. It represents 30 ECTS points and was carried out at the Department of Mechanical Engineering at the Technical University of Denmark from Fe- bruary until August 2010. iii Abstract The present Master Thesis deals with the investigation of suction as a mean of boundary layer control on a wind turbine root airfoil using CFD.
    [Show full text]
  • Review of Flow-Control Devices for Wind-Turbine Performance Enhancement
    energies Review Review of Flow-Control Devices for Wind-Turbine Performance Enhancement Md Zishan Akhter and Farag Khalifa Omar * Department of Mechanical Engineering, United Arab Emirates University, Al Ain 15551, United Arab Emirates; [email protected] * Correspondence: [email protected] Abstract: It is projected that, in the following years, the wind-energy industry will maintain its rapid growth over the last few decades. Such growth in the industry has been accompanied by the desir- ability and demand for larger wind turbines aimed at harnessing more power. However, the fact that massive turbine blades inherently experience increased fatigue and ultimate loads is no secret, which compromise their structural lifecycle. Accordingly, this demands higher overhaul-and-maintenance (O&M) costs, leading to higher cost of energy (COE). Introduction of flow-control devices on the wind turbine is a plausible solution to this issue. Flow-control mechanisms feature the ability to effectively enhance/suppress turbulence, advance/delay flow transition, and prevent/promote separation, leading to enhancement in aerodynamic and aeroacoustics performance, load alleviation and fluctuation suppression, and eventually wind turbine power augmentation. These flow-control devices are operated primarily under two schemes: passive and active control. Development and optimization of flow-control devices present the potential for reduction in the COE, which is a major challenge against traditional power sources. This review performs a comprehensive and up-to-date literature survey of selected flow-control devices, from their time of development up to the present. It contains a discussion on the current prospects and challenges faced by these devices, along with Citation: Akhter, M.Z.; Omar, F.K.
    [Show full text]
  • Design of a Wing with Boundary Layer Suction Redesigning the Wing of the Eaglet
    Master of Science Thesis Design of a Wing with Boundary Layer Suction Redesigning the Wing of the Eaglet H.J.B. van de Wal August 24, 2010 Faculty of Aerospace Engineering Delft University of Technology · Design of a Wing with Boundary Layer Suction Redesigning the Wing of the Eaglet Master of Science Thesis For obtaining the degree of Master of Science in Aerospace Engineering at Delft University of Technology H.J.B. van de Wal August 24, 2010 Faculty of Aerospace Engineering Delft University of Technology · Delft University of Technology Copyright c H.J.B. van de Wal All rights reserved. Delft University Of Technology Department Of Aerodynamics The undersigned hereby certify that they have read and recommend to the Faculty of Aerospace Engineering for acceptance a thesis entitled “Design of a Wing with Boundary Layer Suction” by H.J.B. van de Wal in partial fulfillment of the re- quirements for the degree of Master of Science. Dated: August 24, 2010 Head of department: prof.dr.ir.drs. H. Bijl Supervisor: ir. L.L.M. Boermans Reader: dr.ir. R. Vos Abstract Over the last century lots of efforts have been put in the reduction of profile drag. By using advanced techniques in airfoil design, the passive ways to reduce profile drag by shaping have come to a standstill due to physical limits. To further reduce the profile drag, an active method has to be used. Boundary layer suction is one of these active methods and its effect is twofold. A laminar boundary layer will be stabilized, preventing transition and yielding larger areas of laminar flow, which generate less drag.
    [Show full text]
  • Flow Control Over the Wing of a Fighter-Type Configuration Using Boundary Layer Suction
    ICAS 2002 CONGRESS FLOW CONTROL OVER THE WING OF A FIGHTER-TYPE CONFIGURATION USING BOUNDARY LAYER SUCTION M. R. Soltani, T. Khadivi, A. R. Davari Department of Aerospace Engineering, Sharif University of Technology, Tehran, I. R. Iran Keywords: Cropped Delta Wing, Vortex, Flow Control, Suction, Sweep Angle Abstract performance. Various concepts have been used to prevent or delay separation. The objective of this study is to determine the Boundary layer control remains one of the effectiveness of using an active suction most promising avenues delaying for transition technique to delay flow separation over the and separation, thus improving aircraft wing of a fighter type configuration model. A performance. A primary objective of the number of experiments were conducted on a 40 boundary layer control has always been that of degree swept cropped delta wing, similar to the allowing the flow over the wing surface to be High Alpha Research Vehicle (HARV) model, diffused to the trailing edge without massive operating at two subsonic speeds and at low to separation. moderate angles of attack. Both spanwise The second object being pursued very surface pressure distribution and velocity actively at present is delaying the boundary profiles at various angles of attack for suction layer transition phenomenon hence forcing the on and off cases were measured. Smoke and flow to remain laminar instead of turbulent over tufts were used to visualize the flow over the the vehicle [1]. This process will cause wing at various angles of attack. The results substantial reduction in the skin friction drag of indicate formation of a relatively weak vortex the immersed body.
    [Show full text]