DOCSLIB.ORG

Influence of Aircraft Vortices on Spray Cloud

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read 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. The success of spray- (Hoff et al. 1989, Mickle 1994), and a Bell 2o68 ing is driven by timing of the application and in Jetranger. Atomizers have included 11010 T-jets particular by the applicator, who ultimately is and wind-driven and high (14,000)-rpm electri- responsible for placing the pesticide into the tar- cally driven Micronair AU4OOO rotary atomiz- get area. Typically, aerial spraying for mosqui- ers. Simulants with physical properties similar toes incorporates an emission droplet size dis- to forestry insecticide formulations were used to tribution with a volume median diameter (D"o.r) produce representative emission droplet size dis- below 100 pm. Given the slow settling veloci- tributions. A computer-generated graphics pre- ties of these droplets, their initial motion is con- sentation of examples from both experiments trolled by the wingtip vortices of the spray air- can be obtained from the author. craft (Drummond 1987). Such small droplets The ARAL cloud mapper comprises a small have the disadvantage, however, that if they do Nd-Yag laser pulsing at 70 Hz and receiving op- not impact the target in a short time, they are tics to capture the returning signal. Under the highly susceptible to drift (Picot et al. 1986, control of a laptop computer, the laser beam is Crabbe and McCooeye 1989, Akesson et al. scanned through the spray cloud every 4 sec 1992, Crabbe et al. 1994). with a sweep taking slightly more than 2 sec. In order to diagnose the aerodynamics of the The time of flight of each laser pulse backscat- application technique, the Atmospheric Environ- tered from the droplets in the spray cloud gives ment Service (AES) of Environment Canada un- the range of the cloud from the ARAL, whereas dertook the construction of a lidar system (Hoff the intensity of the returning pulse is a measure et al. 1989, Mickle 1994) that was capable of of the droplet density within the reflecting vol- monitoring the spray drift cloud in real time. The ume of the cloud. Laser beam and receiving op- lidar system measures the intensity of the re- tics divergences permit volume sampling of I m3 turned laser pulse as a function of time (range) of the cloud at distances of I km from the thereby mapping the cloud density cross section ARAL system. The system is, therefore, capable as it moves away from the aircraft flight line. of clearly defining the spray cloud distribution From cross-sectional lidar profiles, it is possible within the wingtip vortices. to visualize the spray cloud application and, giv- Within the vortices (Fig. 1A), the cloud den- en the initial spray droplet size distribution and sity, as seen fTom a single laser pulse, was found a model for subsequent evaporation of the drop- to have 2 maxima of concentration, each asso- lets (Dumbauld et al. 1980, Picot et al. 1981, ciated with a center of the vortex pair. This dis- Mickle 1987, Teske et al. 1993), estimates of the tribution characterized the vast majority of the deposit and drift fractions can be calculated. operational atomizer configurations for ULV 372 373 JUNE1996 Syuposruu: Asnosot- Ct-ouo DvNeutcs 20 z E h15 t coREs tr i-"",:: oio J ul ts-5 J ul tr 0 1000 1100 {200 450 550 650 DISTANGEFROM ARAL (m) DISTANCEFROM ARAL (m) Fig. 1. Backscatter return from a single lidar pulse. A. TBM with 1O wind-driven AU4000 at lO,00O rpm. B. Bell 2O68 with 2 electrically driven AU4OOO at 14,000 rpm. spraying regardless of atomizer configuration or the differences between spraying in parallel and type. The example in Fig. 1A is for a TBM con- crosswinds. Selected cross sections of the spray figured with 5 AU40O0 atomizers mounted ap- cloud for parallel and crosswind cases are com- proximately I m below mid-chord of each wing. pared in Fig. 2 for various times after the aircraft The outermost atomizer was located at 567o of had passed a vertical plane swept by the laser the wing span. Despite the low mounting below beam. In both cases, the aircraft is flying away the wing, clearly the material has been moved from the observer (i.e., into the page) at a dis- spanwise towards the vortex core as the vortices tance of 1-2 km from the ARAL located on the were formed. No atomizers were mounted at the port side of the aircraft. Areas of equal droplet position of the vortex cores. The minimum be- density (concentration) are mapped with colors tween the peaks is associated with the lack of ranging from black (high concentration) to light atomizers below the center of the aircraft. It is gray (less than O.5Voof the high concentration). interesting that the shape of the droplet density A more detailed analysis of this case can be within the cloud is characteristic ofthe expected found in Mickle (1994). Figure 3 presents the deposit profile if an aircraft was flying close to time-integrated concentration (dosage) for these the ground. The only exception (Fig. 18) to this 2 spray cases at different heights and distances general shape was observed for a specialized relative to the flight line. Figure 4 presents the mounting of 2 AU40O0 atomizers near the cen- breathing height concentration of the spray with ter of a pallet slung approximately 3 m below a time, and Fig. 5 gives the accumulated deposit Bell 2068 Jetranger. In this case, the spray from from the loss of material in the surface layer. each atomizer formed an annulus around the Crosswind spray: In this example, a TBM vortex center at a distance characteristic of its with 5 Micronair AU4000 rotary atomizers lateral position from the aircraft center line. Al- (flow rate = 2 liters/min/head; D"o, : 4O-50 though material was found towards the center of pm) mounted under each wing was flown at a the vortex, clearly the contribution to spray height of 25 m above a clear-cut area. Winds at within the vortex core from atomizers at these aircraft height were light (1.8 m/sec) at 7O" to in-board locations is limited compared to the the flight line. Temperatures during this early more outboard locations as shown in the previ- morning stable spray run (0650 h AST) were ous example. near 9"C with relative humidity near 9O7o.With- in 9 sec after aircraft passage, the ULV spray CASE STUDIES had been swept into the wingtip vortices (Fig. Of the many flights that have been mapped, 2A) with the highest concentration (black) found the following 2 examples tend to characterize at the vortex centers. Within these 9 sec, the 374 JounNlr- or rtlg Avenlcat Mosquno CoNrnol AssocrerroN Vol. 12,No.2 TBM WITH AU4OOO TBM WITH 11010TJETS 50 z 100 o F E+o 9 SEC f, 980 3 SEC F z F30 F60 (,u z o 920 o40 o Irl U tv A =20 B F .! I 0 U 0 E z 50 o 100 F t g80 €oo 27 SEC F 27 SEC z E F30 o F60 -_-&- z I (920 (,o o40 q ITI =10 F =20 I U 0 c 0 50 100 €oo 69 SEC g80 ..1, 69 SEC F30 :s-'@'ttt F60 I __+-_ 'rS: I +1.;ls j o20 940 qMqF' 10 i{:,, ':,f' ul IIU - 20 0+ ,:{g:' 0 r050 1100 1150 1200 1250 {750 1800 1850 1900 1950 DISTANCEFROM LIDAR (m) DISTANCE FROM LIDAR (m) Fig. 2. Spray cloud concentration cross sections.A. Crosswind spray. B. Parallel wind spray. Contours representa 2-fold change in concentration. spray cloud had descended nearly lO m, which drift downwind, stretching longitudinally due to is characteristic of the vortex descent rate for the wind shear and with a vertical extent compara- TBM. Over the next 20-30 sec, the upwind vor- ble to the aircraft height. Concentrations within tex maintained its shape, carrying the spray from the cloud were typically less than lOVo of the the port wing as it impacted the ground approx- maximum concentration at 9 sec.
Load more

Recommended publications
  • 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]
  • 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]
  • 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]
  • 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.
    [Show full text]
  • Trailing Vortex Attenuation Devices
    Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection 1985 Trailing vortex attenuation devices. Heffernan, Kenneth G. http://hdl.handle.net/10945/21590 DUDLEY KNOX LIBRARY NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA 93^43 NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS TRAILING VORTEX ATTENUATION DEVICES by Kenneth G. Heffernan June 1985 Thesis Advisor: T. Sarpkaya Approved for public release; distribution is unlimited, T223063 Unclassified SECURITY CLASSIFICATION OF THIS PAGE (Whan Data Entered) REPORT READ INSTRUCTIONS DOCUMENTATION PAGE BEFORE COMPLETING FORM 1. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER 4. TITLE (and Subtitle) 5. TYPE OF REPORT A PERIOD COVERED Dual Master's Thesis; Trailing Vortex Attenuation Devices June 1985 S. PERFORMING ORG. REPORT NUMBER 7. AUTHORC»> 8. CONTRACT OR GRANT NUMBERC*.) Kenneth G. Heffernan 9. PERFORMING ORGANIZATION NAME AND AODRESS 10. PROGRAM ELEMENT. PROJECT, TASK AREA & WORK UNIT NUMBERS Naval Postgraduate School Monterey, California 93943 I. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE June 1985 Naval Postgraduate Schodl 13. NUMBER OF PAGES Monterey, California 93943 109 U. MONITORING AGENCY NAME 4 ADDRESSf/f different from Controlling OHicm) 15. SECURITY CLASS, (ol (his report) Unclassified 15a. DECLASSIFICATION/ DOWNGRADING SCHEDULE 16. DISTRIBUTION ST ATEMEN T (of this Report) Approved for public release; distribution is unlimited. 17. DISTRIBUTION STATEMENT (ol the abstract entered In Block 20, If different from Report) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse aide It necessary and Identify by block number) Trailing Vortices 20. ABSTRACT fConl/nu» on reverse side It necessary and Identity by block number) Trailing vortices generated by large aircraft pose a serious hazard to other planes.
    [Show full text]
  • WINGTIP VORTICES and AIRPLANE LIFT Flying an Airplane Disturbs the Air
    AIAA AEROSPACE M ICRO-LESSON Easily digestible Aerospace Principles revealed for K-12 Students and Educators. These lessons will be sent on a bi-weekly basis and allow grade-level focused learning. - AIAA STEM K-12 Committee. WINGTIP VORTICES AND AIRPLANE LIFT Flying an airplane disturbs the air. The larger the airplane, the larger the disturbance. In this lesson, we discuss the disturbance and what people do about it. Next Generation Science Standards (NGSS): Discipline: Physical Science. Crosscutting Concept: Energy and matter: Flows, cycles, and conservation. Science & Engineering Practice: Developing and using models. GRADES K-2 NGSS: Matter and Its Interactions: Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties. NGSS: Motion and Stability: Forces and Interactions: Plan and conduct an investigation to compare the effects of different strengths or different directions of pushes and pulls on the motion of an object. Up in the sky! It’s a bird! No, it’s a plane! No, it’s a vortex? You have seen birds and know that birds fly. You’ve probably also seen planes, either at airports or flying high in the sky. Maybe you’ve even flown on one yourself. But what about a vortex? Do you know what a tornado is? Have you ever seen one on television? If you’ve seen a picture of a tornado, then you’ve seen an example of a large and powerful vortex. Vortices can be small too, like the little “dust devils” that you might see twirling leaves across a playground, or extremely large, like a hurricane.
    [Show full text]
  • Commercial Aircraft Performance Improvement Using Winglets
    Nikola N. Gavrilović Commercial Aircraft Performance Graduate Research Assistant Improvement Using Winglets University of Belgrade Faculty of Mechanical Engineering Aerodynamic drag force breakdown of a typical transport aircraft shows Boško P. Rašuo that lift-induced drag can amount to as much as 40% of total drag at Full Professor cruise conditions and 80-90% of the total drag in take-off configuration. University of Belgrade Faculty of Mechanical Engineering One way of reducing lift-induced drag is by using wing-tip devices. By applying several types of winglets, which are already used on commercial George S. Dulikravich airplanes, we study their influence on aircraft performance. Numerical Full Professor investigation of five configurations of winglets is described and Florida International University preliminary indications of their aerodynamic performance are provided. Department of Mechanical and Materials Engineering, Miami, Florida, USA Moreover, using advanced multi-objective design optimization software an optimal one-parameter winglet configuration was detrmined that Vladimir Parezanović simultaneously minimizes drag and maximizes lift. Researcher Institute PPRIME, CNRS UPR3346 Poitiers, France Keywords: Winglet, Bionics, Computational fluid dynamics, Drag reduction, Lift-induced drag, Optimization 1. INTRODUCTION of soaring birds and their use of tip feathers to control flight, continued on the quest to reduce induced drag The main motivation for using wingtip devices is and improve aircraft performance and further develop reduction of lift-induced drag force. Environmental the concept of winglets in the late 1970s [4]. This issues and rising operational costs have forced industry research provided a fundamental knowledge and design to improve efficiency of commercial air transport and approach required for extremely attractive option to this has led to some innovative developments for improve aerodynamic efficiency of civilian aircraft, reducing lift-induced drag.
    [Show full text]
  • Tangled Quantum Vortices
    Tangled quantum vortices Carlo F. Barenghi (http://research.ncl.ac.uk/quantum-fluids/) Carlo F. Barenghi Tangled quantum vortices Warning: vortices will interact ! Wingtip vortices move down (Helmholtz Theorem: Vortex lines move with the fluid) Carlo F. Barenghi Tangled quantum vortices Summary Part 1: quantum vortices • Absolute zero • Quantum fluids, Bose-Einstein condensation • Quantum vortices • Vortex reconnections, friction • Gross-Pitaevskii eq, Vortex Filament models • Vortex ring, Kelvin waves, vortex knots Part 2: quantum turbulence Carlo F. Barenghi Tangled quantum vortices Absolute zero: XVII-XVIII centuries Daniel Bernoulli Guillaume Amontons (1663-1705) (1700-1782) • Amontons measured pressure changes induced by temperature changes. He argued that pressure cannot become negative, so there is a minimum temperature (estimated at -240 C) corresponding to no motion. • Daniel Bernoulli's kinetic theory. Carlo F. Barenghi Tangled quantum vortices Absolute zero: XVIII-XIX century • Side track: Heat is a fluid called caloric Antoine Lavoisier (1743-1794) • Back on track: Thermodynamics Lord Kelvin (1824-1907) Carlo F. Barenghi Tangled quantum vortices Absolute zero: XX century 1908 Liquid helium (K. Onnes) 1911 Superconductivity (K. Onnes) 1924 Bose-Einstein condensation (BEC) (Bose & and Einstein) 1937 Superfluid 4He (Kapitza, Allen & Misener) 1938 Link between BEC and superfludity (F. London) 1940s Two-fluid model (Landau, Tisza) 1950s Vortex lines (Onsager, Feynman, Hall & Vinen) 1970s Superfluid 3He (Lee, Osheroff, & Richardson) 1995
    [Show full text]
  • The Design and Experimental Optimization of a Wingtip Vortex Turbine for General Aviation Use
    Theses - Daytona Beach Dissertations and Theses 4-1997 The Design and Experimental Optimization of a Wingtip Vortex Turbine for General Aviation Use Andrew Roberts Embry-Riddle Aeronautical University - Daytona Beach Follow this and additional works at: https://commons.erau.edu/db-theses Part of the Aerospace Engineering Commons, and the Aviation Commons Scholarly Commons Citation Roberts, Andrew, "The Design and Experimental Optimization of a Wingtip Vortex Turbine for General Aviation Use" (1997). Theses - Daytona Beach. 234. https://commons.erau.edu/db-theses/234 This thesis is brought to you for free and open access by Embry-Riddle Aeronautical University – Daytona Beach at ERAU Scholarly Commons. It has been accepted for inclusion in the Theses - Daytona Beach collection by an authorized administrator of ERAU Scholarly Commons. For more information, please contact [email protected]. THE DESIGN AND EXPERIMENTAL OPTIMIZATION OF A WINGTIP VORTEX TURBINE FOR GENERAL AVIATION USE by Andrew Roberts A Thesis Submitted to the Office of Graduate Programs in Partial Fulfillment of the Requirements for the Degree of Master of Science in Aerospace Engineering Embry-Riddle Aeronautical University Daytona Beach, Florida April 1997 UMI Number: EP31827 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.
    [Show full text]
  • Analysis on Reducing the Induced Drag Using the Winglet at the Wingtip
    International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 12, December - 2013 Analysis on Reducing the Induced Drag Using the Winglet at the Wingtip Alekhya Bojja Parthasarathy Garre Assistant Professor, Associate Professor, Aeronautical Engg Dept, Mechanical Engg Dept, MLR Institute of Technology, MLR Institute of Technology, Affiliated to JNTUH, Hyderabad. Affiliated to JNTUH, Hyderabad. Abstract Fig1: Vortices occurring at the wingtips The winglet reduces the induced drag at the wing tips and increases the lift to drag ratio. Wingtip devices are Wingtip devices are used to improve the efficiency of usually intended to improve the efficiency of fixed-wing fixed-wing aircraft [1]. Winglets can also improve aircraft. The winglet also reduces the fuel usage and aircraft handling characteristics. The wingtip devices increases the single engine performance. This paper increase the lift generated at the wingtip, and reduce the deals with Analysis of reducing the induced drag using lift-induced drag caused by wingtip vortices, improving winglet at the wingtip. We have considered the Boeing lift-to-drag ratio. Winglets improve efficiency by 767 wing and attached the winglet to analyze the diffusing the shed wingtip vortex, which in turn performance. Winglets are mounted on the wing tips as reduces the drag due to lift and improves the wing’s lift the vertical extensions. The comparisons were done to over drag ratio [2]. Winglets increase the effective see the performance of winglet at different angles IJERTofIJERT aspect ratio of a wing without adding greatly to the attack. Wing and winglet are designed in Catia V5 then structural stress and hence necessary weight of its analyzed in Ansys CFX workbench and Fluent to structure.
    [Show full text]
  • 9.6 Wingtip Vortices
    9.6 Wingtip vortices Math Methods, D. Craig 2007–02–28 How do airplanes fly? . is a far more subtle question than you may realize. Section 9.6 is a neat example but the physical explanation is a bit sketchy. One thing that is not clearly stated is the Kutta-Zhukovsky theorem:∗ Lift = airspeed·circulation·air density·wingspan For a good general reference on all things flight- related, see http://www.av8n.com/how/ by John S. Denker. The drawings there are fantastic, much better than your text. ∗Zhukovsky is a Russian name, you may see it translit- erated many ways, including Joukowsky! 1 Problem a: Is the circulation C ~v · d~r positive or negative in fig 9.10 for contour C? H Think about ~v · d~r as you go around C. On the top, the airflow is both faster and opposite the sense of C, so the top makes a large negative contribution. The bottom of the flow is slow, but aligned with the sense of C, this gives a small positive contribution. Conclusion: the circulation is negative: ~v · d~r < 0. (1) IC 2 Problem b: See figure 9.11. Just apply Stoke’s theorem to the circulation: ~v · d~r = (∇ × ~v) · dS~ (2) IC ZS For a surface S enclosing the wingtip. The vorticity is just ω~ = ∇ × ~v, (3) so Stoke’s theorem becomes ~v · d~r = ω~ · dS~ . (4) IC ZS which we sought to show. The circulation around a contour is the sum of the vorticity through a surface bounded by that contour.
    [Show full text]