DOCSLIB.ORG

Wingtip Vortices and Free Shear Layer Interaction in The

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Wingtip Vortices and Free Shear Layer Interaction in The WINGTIP VORTICES AND FREE SHEAR LAYER INTERACTION IN THE VICINITY OF MAXIMUM LIFT TO DRAG RATIO LIFT CONDITION Dissertation Submitted to The School of Engineering of the UNIVERSITY OF DAYTON In Partial Fulfillment of the Requirements for The Degree of Doctor of Philosophy in Engineering By Muhammad Omar Memon, M.S. UNIVERSITY OF DAYTON Dayton, Ohio May, 2017 WINGTIP VORTICES AND FREE SHEAR LAYER INTERACTION IN THE VICINITY OF MAXIMUM LIFT TO DRAG RATIO LIFT CONDITION Name: Memon, Muhammad Omar APPROVED BY: _______________________ _______________________ Aaron Altman Markus Rumpfkeil Advisory Committee Chairman Committee Member Professor; Director, Graduate Aerospace Program Associate Professor Mechanical and Aerospace Engineering Mechanical and Aerospace Engineering _______________________ _______________________ Jose Camberos Wiebke S. Diestelkamp Committee Member Committee Member Adjunct Professor Professor & Chair Mechanical and Aerospace Engineering Department of Mathematics _______________________ _______________________ Robert J. Wilkens, PhD., P.E. Eddy M. Rojas, PhD., M.A., P.E. Associate Dean for Research and Innovation Dean, School of Engineering Professor School of Engineering ii © Copyright by Muhammad Omar Memon All rights reserved 2017 iii ABSTRACT WINGTIP VORTICES AND FREE SHEAR LAYER INTERACTION IN THE VICINITY OF MAXIMUM LIFT TO DRAG RATIO LIFT CONDITION Name: Memon, Muhammad Omar University of Dayton Advisor: Dr. Aaron Altman Cost-effective air-travel is something everyone wishes for when it comes to booking flights. The continued and projected increase in commercial air travel advocates for energy efficient airplanes, reduced carbon footprint, and a strong need to accommodate more airplanes into airports. All of these needs are directly affected by the magnitudes of drag these aircraft experience and the nature of their wingtip vortex. A large portion of the aerodynamic drag results from the airflow rolling from the higher pressure side of the wing to the lower pressure side, causing the wingtip vortices. The generation of this particular drag is inevitable however, a more fundamental understanding of the phenomenon could result in applications whose benefits extend much beyond the relatively minuscule benefits of commonly-used winglets. Maximizing airport efficiency calls for shorter intervals between takeoffs and landings. Wingtip vortices can be hazardous for following aircraft that may fly directly through the high-velocity swirls causing upsets at vulnerably low iv speeds and altitudes. The vortex system in the near wake is typically more complex since strong vortices tend to continue developing throughout the near wake region. Several chord lengths distance downstream of a wing, the so-called fully rolled up wing wake evolves into a combination of a discrete wingtip vortex pair and a free shear layer. Lift induced drag is generated as a byproduct of downwash induced by the wingtip vortices. The parasite drag results from a combination of form/pressure drag and the upper and lower surface boundary layers. These parasite effects amalgamate to create the free shear layer in the wake. While the wingtip vortices embody a large portion of the total drag at lifting angles, flow properties in the free shear layer also reveal their contribution to the aerodynamic efficiency of the aircraft. Since aircraft rarely cruise at maximum aerodynamic efficiency, a better understanding of the balance between the lift induced drag (wingtip vortices) and parasite drag (free shear layer) can have a significant impact. Particle Image Velocimetry (PIV) experiments were performed at a) a water tunnel at ILR Aachen, Germany, and b) at the University of Dayton Low Speed Wind Tunnel in the near wake of an AR 6 wing with a Clark-Y airfoil to investigate the characteristics of the wingtip vortex and free shear layer at angles of attack in the vicinity of maximum aerodynamic efficiency for the wing. The data was taken 1.5 and 3 chord lengths downstream of the wing at varying free-stream velocities. A unique exergy-based technique was introduced to quantify distinct changes in the wingtip vortex axial core flow. The existence of wingtip vortex axial core flow transformation from wake-like (velocity v less-than the freestream) to jet-like (velocity greater-than the freestream) behavior in the vicinity of the maximum (L/D) angles was observed. The exergy-based technique was able to identify the change in the out of plane profile and corresponding changes in the L/D performance. The resulting velocity components in and around the free shear layer in the wing wake showed counter flow in the cross-flow plane presumably corresponding to behavior associated with the flow over the upper and lower surfaces of the wing. Even though the velocity magnitudes in the free shear layer in cross-flow plane are a small fraction of the freestream velocity (~10%), significant directional flow was observed. An indication of the possibility of the transfer of momentum (from inboard to outboard of the wing) was identified through spanwise flow corresponding to the upper and lower surfaces through the free shear layer in the wake. A transition from minimal cross flow in the free shear layer to a well-established shear flow in the spanwise direction occurs in the vicinity of maximum lift-to-drag ratio (max L/D) angle of attack. A distinctive balance between the lift induced drag and parasite drag was identified. Improved understanding of this relationship could be extended not only to improve aircraft performance through the reduction of lift induced drag, but also to air vehicle performance in off-design cruise conditions. vi DEDICATION Dedicated to my parents vii ACKNOWLEDGEMENTS First of foremost, all praise and thanks to Almighty Allah (God) for blessing me throughout this journey and giving me strength to undertake the graduate program and the dissertation research. This accomplishment would not have been possible without His desire, guidance and help. I would like to thank my advisor, Dr. Aaron Altman, for constantly guiding and supporting me during the course of my PhD program. I have learned a great deal from Dr. Altman whether it is academics, research or valuable life lessons. He has set an example of excellence as an advisor, researcher, and role model. I am ever thankful to him for being very genuine, caring, and supportive in all aspects of our relationship. I would like to extend my sincere thanks to the committee members Dr. Markus Rumpkeil, Dr. Jose Camberos, and Dr. Wiebke Diestelkamp for sharing their knowledge and wisdom when it comes to research. I am thankful to them for being on my PhD committee and evaluating my research. I would also like to thank my former and present colleagues Kevin Wabick, Sidaard Gunasekaran, and Saad Qureshi for their immense support and help throughout this project. From spending countless hours in the lab to preparing for conferences, these people have always provided unconditional help and support. viii I owe my deepest gratitude to my amazing family for their love, support, and prayers for my health and success. This work would not have been possible without their love and encouragement. Last but not the least, I would like to thank Remah Alshinina for her love and support throughout the course of my degree. ix TABLE OF CONTENTS ABSTRACT ........................................................................................................................ iv DEDICATION ................................................................................................................... vii ACKNOWLEDGEMENTS .............................................................................................. viii LIST OF FIGURES ........................................................................................................... xii NOMENCLATURE ......................................................................................................... xix CHAPTER 1 INTRODUCTION ........................................................................................ 1 CHAPTER 2 LITERATURE REVIEW ............................................................................. 4 2.1 Introduction ...................................................................................................... 4 2.2 Wingtip Vortices............................................................................................... 4 2.3 Free Shear Layer ............................................................................................... 9 2.4 Exergy Based Analysis ................................................................................... 10 2.5 Challenges in Cross-stream PIV ..................................................................... 12 CHAPTER 3 EXPERIMENTAL SETUP ........................................................................ 15 3.1 Water Tunnel – ILR Aachen, Germany .......................................................... 15 3.2 Wind Tunnel – University of Dayton Low Speed Wind Tunnel (UD-LSWT)............................................................................................................... 19 CHAPTER 4 ANALYTICAL PERSPECTIVE................................................................ 25 4.1 Error Analysis ................................................................................................. 27 4.2 Vortex Identification ....................................................................................... 29 4.3 Vortex Wandering Correction .......................................................................
Load more

Recommended publications
  • Experimental Analysis of a Low Cost Lift and Drag Force Measurement System for Educational Sessions
    International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 04 Issue: 09 | Sep -2017 www.irjet.net p-ISSN: 2395-0072 Experimental Analysis of a Low Cost Lift and Drag Force Measurement System for Educational Sessions Asutosh Boro B.Tech National Institute of Technology Srinagar Indian Institute of Science, Bangalore 560012 ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - A low cost Lift and Drag force measurement wind- tunnel and used for educational learning with good system was designed, fabricated and tested in wind tunnel accuracy. In addition, an indirect wind tunnel velocity to be used for basic practical lab sessions. It consists of a measurement capability of the designed system was mechanical linkage system, piezo-resistive sensors and tested. NACA airfoil 4209 was chosen as the test subject to NACA Airfoil to test its performance. The system was tested measure its performance and tests were done at various at various velocities and angle of attacks and experimental angles of attack and velocities 11m/s, 12m/s and 14m/s. coefficient of lift and drag were then compared with The force and coefficient results obtained were compared literature values to find the errors. A decent accuracy was with literature data from airfoil tools[1] to find the deduced from the lift data and the considerable error in system’s accuracy. drag was due to concentration of drag forces across a narrow force range and sensor’s fluctuations across that 1.1 Methodology range. It was inferred that drag system will be as accurate as the lift system when the drag forces are large.
    [Show full text]
  • Sailing for Performance
    SD2706 Sailing for Performance Objective: Learn to calculate the performance of sailing boats Today: Sailplan aerodynamics Recap User input: Rig dimensions ‣ P,E,J,I,LPG,BAD Hull offset file Lines Processing Program, LPP: ‣ Example.bri LPP_for_VPP.m rigdata Hydrostatic calculations Loading condition ‣ GZdata,V,LOA,BMAX,KG,LCB, hulldata ‣ WK,LCG LCF,AWP,BWL,TC,CM,D,CP,LW, T,LCBfpp,LCFfpp Keel geometry ‣ TK,C Solve equilibrium State variables: Environmental variables: solve_Netwon.m iterative ‣ VS,HEEL ‣ TWS,TWA ‣ 2-dim Netwon-Raphson iterative method Hydrodynamics Aerodynamics calc_hydro.m calc_aero.m VS,HEEL dF,dM Canoe body viscous drag Lift ‣ RFC ‣ CL Residuals Viscous drag Residuary drag calc_residuals_Newton.m ‣ RR + dRRH ‣ CD ‣ dF = FAX + FHX (FORCE) Keel fin drag ‣ dM = MH + MR (MOMENT) Induced drag ‣ RF ‣ CDi Centre of effort Centre of effort ‣ CEH ‣ CEA FH,CEH FA,CEA The rig As we see it Sail plan ≈ Mainsail + Jib (or genoa) + Spinnaker The sail plan is defined by: IMSYC-66 P Mainsail hoist [m] P E Boom leech length [m] BAD Boom above deck [m] I I Height of fore triangle [m] J Base of fore triangle [m] LPG Perpendicular of jib [m] CEA CEA Centre of effort [m] R Reef factor [-] J E LPG BAD D Sailplan modelling What is the purpose of the sails on our yacht? To maximize boat speed on a given course in a given wind strength ‣ Max driving force, within our available righting moment Since: We seek: Fx (Thrust vs Resistance) ‣ Driving force, FAx Fy (Side forces, Sails vs. Keel) ‣ Heeling force, FAy (Mx (Heeling-righting moment)) ‣ Heeling arm, CAE Aerodynamics of sails A sail is: ‣ a foil with very small thickness and large camber, ‣ with flexible geometry, ‣ usually operating together with another sail ‣ and operating at a large variety of angles of attack ‣ Environment L D V Each vertical section is a differently cambered thin foil Aerodynamics of sails TWIST due to e.g.
    [Show full text]
  • University of Oklahoma Graduate College Design and Performance Evaluation of a Retractable Wingtip Vortex Reduction Device a Th
    UNIVERSITY OF OKLAHOMA GRADUATE COLLEGE DESIGN AND PERFORMANCE EVALUATION OF A RETRACTABLE WINGTIP VORTEX REDUCTION DEVICE A THESIS SUBMITTED TO THE GRADUATE FACULTY In partial fulfillment of the requirements for the Degree of Master of Science Mechanical Engineering By Tausif Jamal Norman, OK 2019 DESIGN AND PERFORMANCE EVALUATION OF A RETRACTABLE WINGTIP VORTEX REDUCTION DEVICE A THESIS APPROVED FOR THE SCHOOL OF AEROSPACE AND MECHANICAL ENGINEERING BY THE COMMITTEE CONSISTING OF Dr. D. Keith Walters, Chair Dr. Hamidreza Shabgard Dr. Prakash Vedula ©Copyright by Tausif Jamal 2019 All Rights Reserved. ABSTRACT As an airfoil achieves lift, the pressure differential at the wingtips trigger the roll up of fluid which results in swirling wakes. This wake is characterized by the presence of strong rotating cylindrical vortices that can persist for miles. Since large aircrafts can generate strong vortices, airports require a minimum separation between two aircrafts to ensure safe take-off and landing. Recently, there have been considerable efforts to address the effects of wingtip vortices such as the categorization of expected wake turbulence for commercial aircrafts to optimize the wait times during take-off and landing. However, apart from the implementation of winglets, there has been little effort to address the issue of wingtip vortices via minimal changes to airfoil design. The primary objective of this study is to evaluate the performance of a newly proposed retractable wingtip vortex reduction device for commercial aircrafts. The proposed design consists of longitudinal slits placed in the streamwise direction near the wingtip to reduce the pressure differential between the pressure and the suction sides.
    [Show full text]
  • How Do Wings Generate Lift? 2
    GENERAL ARTICLE How Do Wings Generate Lift? 2. Myths, Approximate Theories and Why They All Work M D Deshpande and M Sivapragasam A cambered surface that is moving forward in a fluid gen- erates lift. To explain this interesting fact in terms of sim- pler models, some preparatory concepts were discussed in the first part of this article. We also agreed on what is an accept- able explanation. Then some popular models were discussed. Some quantitative theories will be discussed in this conclud- ing part. Finally we will tie up all these ideas together and connect them to the rigorous momentum theorem. M D Deshpande is a Professor in the Faculty of Engineering The triumphant vindication of bold theories – are these not the and Technology at M S Ramaiah University of pride and justification of our life’s work? Applied Sciences. Sherlock Holmes, The Valley of Fear Sir Arthur Conan Doyle 1. Introduction M Sivapragasam is an We start here with two quantitative theories before going to the Assistant Professor in the momentum conservation principle in the next section. Faculty of Engineering and Technology at M S Ramaiah University of Applied 1.1 The Thin Airfoil Theory Sciences. This elegant approximate theory takes us further than what was discussed in the last two sections of Part 111, and quantifies the Resonance, Vol.22, No.1, ideas to get expressions for lift and moment that are remarkably pp.61–77, 2017. accurate. The pressure distribution on the airfoil, apart from cre- ating a lift force, leads to a nose-up or nose-down moment also.
    [Show full text]
  • A Concept of the Vortex Lift of Sharp-Edge Delta Wings Based on a Leading-Edge-Suction Analogy Tech Library Kafb, Nm
    I A CONCEPT OF THE VORTEX LIFT OF SHARP-EDGE DELTA WINGS BASED ON A LEADING-EDGE-SUCTION ANALOGY TECH LIBRARY KAFB, NM OL3042b NASA TN D-3767 A CONCEPT OF THE VORTEX LIFT OF SHARP-EDGE DELTA WINGS BASED ON A LEADING-EDGE-SUCTION ANALOGY By Edward C. Polhamus Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - Price $1.00 A CONCEPT OF THE VORTEX LIFT OF SHARP-EDGE DELTA WINGS BASED ON A LEADING-EDGE-SUCTION ANALOGY By Edward C. Polhamus Langley Research Center SUMMARY A concept for the calculation of the vortex lift of sharp-edge delta wings is pre­ sented and compared with experimental data. The concept is based on an analogy between the vortex lift and the leading-edge suction associated with the potential flow about the leading edge. This concept, when combined with potential-flow theory modified to include the nonlinearities associated with the exact boundary condition and the loss of the lift component of the leading-edge suction, provides excellent prediction of the total lift for a wide range of delta wings up to angles of attack of 20° or greater. INTRODUCTION The aerodynamic characteristics of thin sharp-edge delta wings are of interest for supersonic aircraft and have been the subject of theoretical and experimental studies for many years in both the subsonic and supersonic speed ranges. Of particular interest at subsonic speeds has been the formation and influence of the leading-edge separation vor­ tex that occurs on wings having sharp, highly swept leading edges.
    [Show full text]
  • Aviation Glossary
    AVIATION GLOSSARY 100-hour inspection – A complete inspection of an aircraft operated for hire required after every 100 hours of operation. It is identical to an annual inspection but may be performed by any certified Airframe and Powerplant mechanic. Absolute altitude – The vertical distance of an aircraft above the terrain. AD - See Airworthiness Directive. ADC – See Air Data Computer. ADF - See Automatic Direction Finder. Adverse yaw - A flight condition in which the nose of an aircraft tends to turn away from the intended direction of turn. Aeronautical Information Manual (AIM) – A primary FAA publication whose purpose is to instruct airmen about operating in the National Airspace System of the U.S. A/FD – See Airport/Facility Directory. AHRS – See Attitude Heading Reference System. Ailerons – A primary flight control surface mounted on the trailing edge of an airplane wing, near the tip. AIM – See Aeronautical Information Manual. Air data computer (ADC) – The system that receives and processes pitot pressure, static pressure, and temperature to present precise information in the cockpit such as altitude, indicated airspeed, true airspeed, vertical speed, wind direction and velocity, and air temperature. Airfoil – Any surface designed to obtain a useful reaction, or lift, from air passing over it. Airmen’s Meteorological Information (AIRMET) - Issued to advise pilots of significant weather, but describes conditions with lower intensities than SIGMETs. AIRMET – See Airmen’s Meteorological Information. Airport/Facility Directory (A/FD) – An FAA publication containing information on all airports, seaplane bases and heliports open to the public as well as communications data, navigational facilities and some procedures and special notices.
    [Show full text]
  • Aircraft Winglet Design
    DEGREE PROJECT IN VEHICLE ENGINEERING, SECOND CYCLE, 15 CREDITS STOCKHOLM, SWEDEN 2020 Aircraft Winglet Design Increasing the aerodynamic efficiency of a wing HANLIN GONGZHANG ERIC AXTELIUS KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF ENGINEERING SCIENCES 1 Abstract Aerodynamic drag can be decreased with respect to a wing’s geometry, and wingtip devices, so called winglets, play a vital role in wing design. The focus has been laid on studying the lift and drag forces generated by merging various winglet designs with a constrained aircraft wing. By using computational fluid dynamic (CFD) simulations alongside wind tunnel testing of scaled down 3D-printed models, one can evaluate such forces and determine each respective winglet’s contribution to the total lift and drag forces of the wing. At last, the efficiency of the wing was furtherly determined by evaluating its lift-to-drag ratios with the obtained lift and drag forces. The result from this study showed that the overall efficiency of the wing varied depending on the winglet design, with some designs noticeable more efficient than others according to the CFD-simulations. The shark fin-alike winglet was overall the most efficient design, followed shortly by the famous blended design found in many mid-sized airliners. The worst performing designs were surprisingly the fenced and spiroid designs, which had efficiencies on par with the wing without winglet. 2 Content Abstract 2 Introduction 4 Background 4 1.2 Purpose and structure of the thesis 4 1.3 Literature review 4 Method 9 2.1 Modelling
    [Show full text]
  • Prediction of Laminar/Turbulent Transition in Airfoil Flows
    PREDICTION OF LAMINAR/TURBULENT TRANSITION IN AIRFOIL FLOWS by Jeppe Johansen and Jens Norkaer Sorensen DTU FLUID MECHANICS H ENERGY ENGINEERING TECHNICAL UNIVERSITY OF DENMARK / DANISH CENTER FOR APPLIED MATHEMATICS AND MECHANICS Scientific Council Poul Andersen Dept, of Naval Architecture and Offshore Engineering Martin P. Bends0e Dept, of Mathematics Ove Ditlevsen Dept, of Structural Engineering and Materials Ivar G. Jonsson Dept, of Hydrodynamics and Water Resources Wolfhard Kliem Dept, of Mathematics Steen Krenk Dept, of Structural Engineering and Materials P. Scheel Larsen Dept, of Energy Engineering Frithiof I. Niordson Dept, of Solid Mechanics Pauli Pedersen Dept, of Solid Mechanics P. Temdrup Pedersen Dept, of NavalArchitecture and Offshore Engineering- Dan Rosbjerg Dept. of Hydrodynamics and Water Resources Jens Nprkser Sprensen Dept, of Energy Engineering P. Grove Thomsen Dept, of Mathematical Modelling Hans True Dept, of Mathematical Modelling Viggo Tvergaard Dept, of Solid Mechanics Secretary Pauli Pedersen, Docent, Dr.techn. Department of Solid Mechanics, Building 404 Technical University of Denmark DK-2800 Lyngby, Denmark DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Prediction of Laminar/Turbulent Transition in Airfoil Flows Jeppe Johansen* and Jens N. Sprensen* * Ris0 National Laboratory, Denmark and * Department of Energy Engineering, Technical University of Denmark Presented as Paper 98-0702 at the AIAA 36th Aerospace Sciences Meeting Sc Exhibit, Reno, NV, January 12*15, 1998 tphD student, Wind Energy and Atmospheric Physics Department, Rise National Laboratory, DK-4000 RoskUde, Denmark * Associate Professor, Department of Energy Engineering, Technical University of Denmark, DK- 2800 Lyngby, Denmark 1 Abstract The prediction of the location of transition is important for low Reynolds number airfoil flows.
    [Show full text]
  • Advanced RANS Modeling of Wingtip Vortex Flows
    Center for Turbulence Research 73 Proceedings of the Summer Program 2006 Advanced RANS modeling of wingtip vortex flows By A. Revell , G. Iaccarino AND X. Wu y The numerical calculation of the trailing vortex shed from the wingtip of an aircraft has attracted significant attention in recent years. An accurate prediction of the flow over the wing is required to provide the correct initial conditions for the trailing vortex, while careful modeling is also necessary in order to account for the turbulence in the vortex core. As such, recent works have concluded that in order to achieve results of satisfac- tory accuracy, the use of complex turbulence modeling closures and numerical grids of considerable size is an absolute necessity. In Craft et al. (2006) it was proposed that a Reynolds stress-transport model (RSM) should be used, while Duraisamy & Iaccarino (2005) obtained optimal results with a version of the v2 f which was specifically sen- sitised to streamline curvature. The authors report grid requiremen− ts upward of 7 106 grid points, highlighting the substantial numerical cost involved with predicting this×flow. The computations here are reported for the flow over a NACA0012 half-wing with rounded wingtip at an incidence angle of 10◦, as measured by Chow et al. (1997). The primary aim is to assess the performance of a new turbulence modeling scheme which accounts for the stress-strain misalignment effects in a turbulent flow. This three-equation model bridges the gap between popular two equation eddy-viscosity models (EVM) and the seven equations of a RSM. Relative to a RSM, this new approach inherits the stability advantages of an eddy-viscosity scheme, together with a lower computational expense, and it has already been validated for a range of unsteady mean flows (Revell 2006).
    [Show full text]
  • Computational Fluid Dynamic Analysis of Scaled Hypersonic Re-Entry Vehicles
    Computational Fluid Dynamic Analysis of Scaled Hypersonic Re-Entry Vehicles A project presented to The Faculty of the Department of Aerospace Engineering San Jose State University In partial fulfillment of the requirements for the degree Master of Science in Aerospace Engineering by Simon H.B. Sorensen March 2019 approved by Dr. Periklis Papadopoulous Faculty Advisor 1 i ABSTRACT With the advancement of technology in space, reusable re-entry space planes have become a focus point with their ability to save materials and utilize existing flight data. Their ability to not only supply materials to space stations or deploy satellites, but also in atmosphere flight makes them versatile in their deployment and recovery. The existing design of vehicles such as the Space Shuttle Orbiter and X-37 Orbital Test Vehicle can be used to observe the effects of scaling existing vehicle geometry and how it would operate in identical conditions to the full-size vehicle. These scaled vehicles, if viable, would provide additional options depending on mission parameters without losing the advantages of reusable re-entry space planes. 2 Table of Contents Abstract . i Nomenclature . .1 1. Introduction. .1 2. Literature Review. 2 2.1 Space Shuttle Orbiter. 2 2.2 X-37 Orbital Test Vehicle. 3 3. Assumptions & Equations. 3 3.1 Assumptions. 3 3.2 Equations to Solve. 4 4. Methodology. 5 5. Base Sized Vehicles. 5 5.1 Space Shuttle Orbiter. 5 5.2 X-37. 9 6. Scaled Vehicles. 11 7. Simulations. 12 7.1 Initial Conditions. 12 7.2 Initial Test Utilizing X-37. .13 7.3 X-37 OTV.
    [Show full text]
  • Influence of Aircraft Vortices on Spray Cloud
    Journal of the American Mosquito Control Association, 12(2):372_379, 1996 Copyright O 1996 by the American Mosquito Control Association, Inc. INFLUENCE OF AIRCRAFT VORTICESON SPRAY CLOUD BEHAVIOR R. E. MICKLE Atmospheric Environment Service, 4905 Dufferin Street, Downsview, Ontario M3H5T4, Canada ABSTRACT. For small droplet spraying, the spray cloud is initially entrained into the wingtip vortices so that the ultimate fate of the spray is conffolled by the motion of these vortices. In close to 10O aerial sprays, the emitted spray cloud has been mapped using a scanning laser system that displays diffusion and transport of the spray cloud. Results detailing the concentrations within the spray cloud in space and time are given for sprays in parallel and crosswinds. Wind direction is seen to potentially alter the vortex motion and hence the fate of the spray cloud. In crosswind spraying, the vortex behavior associated with the 2 wings is found to differ, which leads to enhanced deposition from the upwind wing and enhanced drift from the downwind wins. INTRODUCTION EXPERIMENTAL METHODS The application of larvicides and adulticides The ARAL (AES Rapid Acquisition Lidar) by aircraft has been an effective mechanism for has been used in 2 experiments to map close to mosquito control. Howevet the benefits of 100 different spray scenarios in a variety of me- spraying are accompanied by the difficulty in teorological conditions (stable and unstable) en- targeting small droplets and by the potential en- compassing light to high winds at cross and par- vironmental impact of applying any chemical allel angles to the flight line. Aircraft used in into the environment in quantities that may be these studies have included a Cessna 188, TBM toxic to nontarget species.
    [Show full text]
  • Lift for a Finite Wing
    Lift for a Finite Wing • all real wings are finite in span (airfoils are considered as infinite in the span) The lift coefficient differs from that of an airfoil because there are strong vortices produced at the wing tips of the finite wing, which trail downstream. These vortices are analogous to mini-tornadoes, and like a tornado, they reach out in the flow field and induce changes in the velocity and pressure fields around the wing Imagine that you are standing on top of the wing you will feel a downward component of velocity over the span of the wing, induced by the vortices trailing downstream from both tips. This downward component of velocity is called downwash. The local downwash at your location combines with the free-stream relative wind to produce a local relative wind. This local relative wind is inclined below the free- stream direction through the induced angle of attack α i . Hence, you are effectively feeling an angle of attack different from the actual geometric angle of attack of the wing relative to the free stream; you are sensing a smaller angle of attack. For Example if the wing is at a geometric angle of attack of 5°, you are feeling an effective angle of attack which is smaller. Hence, the lift coefficient for the wing is going to be smaller than the lift coefficient for the airfoil. This explains the answer given to the question posed earlier. High-Aspect-Ratio Straight Wing The classic theory for such wings was worked out by Prandtl during World War I and is called Prandtl's lifting line theory.
    [Show full text]