DOCSLIB.ORG

Identification of Coaxial-Rotors Dynamic Wake Inflow for Flight Dynamics and Aeroelastic Applications

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Identification of Coaxial-Rotors Dynamic Wake Inflow for Flight Dynamics and Aeroelastic Applications 42st European Rotorcraft Forum 2016 IDENTIFICATION OF COAXIAL-ROTORS DYNAMIC WAKE INFLOW FOR FLIGHT DYNAMICS AND AEROELASTIC APPLICATIONS Felice Cardito, Riccardo Gori, Giovanni Bernardini Jacopo Serafini, Massimo Gennaretti Department of Engineering, University Roma Tre, Rome, Italy Abstract This paper presents the development of a linear, finite-state, dynamic perturbation model for wake inflow of coaxial rotors in arbitrary steady flight, based on high-accuracy radial and azimuthal representations. It might conveniently applied in combination with blade element formulations for rotor aeroelastic mod- elling, where three-dimensional, unsteady multiharmonic and localized aerodynamic effects may play a crucial role. The proposed model is extracted from responses provided by an arbitrary high-fidelity CFD solver to perturbations of rotor degrees of freedom and controls. The transfer functions of the multihar- monic responses are then approximated through a rational-matrix approach, which returns a constant coefficient differential operator relating the inflow multiharmonic coefficients to the inputs. The accuracy of the model is tested both for hovering and forward flight by comparison with the wake inflow directly evaluated by the high-fidelity CFD tool for arbitrary inputs. 1. INTRODUCTION ing the need for a tail rotor and its associated shafting and gearboxes. Due to the improved performance they may provide, coaxial rotors are expected to become a common solu- While coaxial rotors have been investigated since the tion for next-generation rotorcraft. begin of aeronautics, for decades, the increased com- plexity of rotor hub suggested the manufacturers to use Indeed, as the forward flight speed increases, the differ- simpler main-tail rotor configurations. Nowadays, the ence of dynamic pressure between the advancing and difficulties in overcoming the limits of single rotor heli- retreating sides of a single rotor becomes greater, mak- copters resulted in a growing interest for coaxial rotor ing necessary higher values of the cyclic pitch to main- configurations as demonstrated by the Sikorsky X2 and tain the aircraft trimmed. In order to avoid blade stall on the Kamov Ka-92 projects, among the others. the retreating side of the rotor disk, the amount of col- lective pitch has to be correspondingly reduced, thus This fact motivates the development of dedicated com- negatively affecting the rotor thrust capability. [1] putational tools suited for their analysis. Dynamic wake inflow modeling is one of the main issues in ef- In coaxial, contra-rotating rotors the advancing blades ficient and reliable rotorcraft simulation tools concern- of each rotor may operate at higher pitch angles to ing aeroelasticity, flight mechanics, and handling qual- produce more lift without compromising roll trim. At ity assessment, as well as for flight control laws defini- the same time, the retreating blade may be kept far tion. [3–5] The most widely used dynamic inflow models from stall, with two major consequences: i) rotor RPM for single rotors (see for instance, Refs. [6,7]) cannot be may be reduced, increasing the speed at which tran- extended to coaxial rotors with satisfactory accuracy, sonic effects arise at the tip of advancing blades, and due to the importance of the aerodynamic interaction ii) the overall vibratory loads transmitted to the fuselage effects occurring. are strongly reduced, thus allowing the employment of stiffer blades that improve helicopter manoeuvrability. [2] This paper presents the development of a linear, finite- In addition, the maximum lift-to-drag ratio is improved: state, dynamic perturbation model for wake inflow of the coaxial rotors have proven to be intrinsically more coaxial rotors in arbitrary steady flight, based on high- efficient in hover, forward flight than single rotors of the accuracy radial and azimuthal representations. It is ex- same solidity and blade geometry. Furthermore, coax- tracted through a numerical process starting with the ial rotors provide torque cancellation, thereby eliminat- evaluation of wake inflow corresponding to perturba- 42st European Rotorcraft Forum 2016 tions of rotor degrees of freedom and controls by a a high-fidelity aerodynamic solver, it might be applica- high-fidelity CFD solver. Next the transfer functions of ble to arbitrary multi-body rotor configurations and flight the multiharmonic responses are identified, and then conditions. approximated through a rational-matrix approach. This returns constant coefficient differential operators relat- 2.1. Inflow Representation ing the inflow multiharmonic coefficients to the input perturbations (see later for details). Here the wake in- In order to represent the complex wake inflow field over flow responses are evaluated through simulations pro- a rotor blade with a level of accuracy suitable for (high- vided by a Boundary Element Method (BEM) tool for frequency) aeroelastic applications, it is expressed in a potential-flow solutions, suited for rotors in arbitrary mo- non-rotating frame in terms of spanwise-varying multi- tion. [8] It is capable of taking into account free-wake blade variables. and aerodynamic interference effects in multi-body con- Indeed, introducing over the rotor disc the hub-fixed po- figurations, as well as the effects due to severe blade- lar coordinate system, (r; ), for (both upper and lower) vortex interactions. three-bladed rotors (typically considered in coaxial ro- The wake inflow modelling presented here may be con- tor configurations), the perturbation wake inflow, v, is sidered as a direct extension to coaxial rotors of the represented through the following extension of the form formulation introduced in Ref. [9] for isolated rotors applied in the Pitt-Peters model [6, 12] which, in turn, extended the LTI, finite-state wake inflow (1) v(r; i; t) = v0(r; t) + vc(r; t) cos i + vs(r; t) sin( i) modelling approach presented in Ref. [10] to include the multi-harmonic effects related to the intrinsic time- where i denotes the azimuth position of the i-th blade, periodic nature of advancing, rotor aerodynamics, as whereas v0; vc and vs are, respectively, the instan- well as the complex radial distributions induced by the taneous multiblade collective and cyclic inflow coeffi- wake-blade interactions. cients at a given radial position, r (see also Ref. [9] for higher number of rotor blades). Considering a coaxial rotor in hovering and advancing flight conditions, the numerical investigation presents For vi denoting the wake inflow perturbation evaluated the identified transfer functions and the assessment of by the high-fidelity aerodynamic tool on the i-th rotor the accuracy of the proposed dynamic inflow model by blade, applying the separation of variables technique, comparison with wake inflow directly calculated by the and choosing suitable sets of linearly independent ra- α time-marching BEM solver. Particular attention is fo- dial basis functions, φj (r), the multiblade wake inflow cused on the examination of the capability of captur- coefficients are expressed in the following form ing radial distributions and multi-harmonic components 0 N N arising in forward flight. 1 Xb Xr v (r; t) = v (r; t) = λ0(t) φ0(r) 0 N i j j b i=1 j=1 c 2. WAKE INFLOW MODELLING Nb Nr 2 X X c c The multi-harmonic wake inflow perturbation model (2) vc(r; t) = vi(r; t) cos i = λj(t) φj(r) Nb presented here is suited for coaxial rotors aeroelastic i=1 j=1 s applications, and is an extension of those proposed by Nb Nr [9–11] 2 X X s s the authors in Refs. vs(r; t) = vi(r; t) sin i = λj (t) φj (r) Nb The main steps of the process of wake inflow model ex- i=1 j=1 α traction from arbitrary high-fidelity aerodynamic solver where Nb denotes the number of rotor blades, Nr is the are: definition of a suited approximation form of the in- number of functions used to define the α-coefficient ra- α flow distributions; LTI representation of the model pa- dial distribution, with λj representing the corresponding α rameters identified from responses of the aerodynamic component onto the basis function φj . It is worth noting 0 c s 0 c s solver; finite-state approximation of the parameters dy- that, for Nr = Nr = Nr = 1, φ1 = 1, and φ1 = φ1 = r, namics, and hence of the inflow model. the proposed inflow distribution coincides with that of [6, 12] The model inputs are the rotor degrees of freedom and the Pitt-Peters model. controls (in this case including upper and lower rotor blade collective and cyclic pitches). Its accuracy de- 2.2. Model Parameters Extraction pends on that of the CFD solver used for the evalua- The extraction of the dynamic wake inflow model from tion of the aerodynamic responses. Since derived from high-fidelity aerodynamics starts with the identification 42st European Rotorcraft Forum 2016 of the transfer functions relating the perturbations of the 2.3. Finite-State Approximation system state variables (namely, rotor rigid and elastic The transfer functions between inputs and the (upper degrees of freedom) with the components of the inflow and lower rotor) inflow parameters introduced in Eq. (3) multiblade coefficients. represent LTI dynamics, thus allowing the description To this purpose, following an approach similar to that of a LTP operator through combination of outputs of LTI used in Refs. [9–11], first, a high-fidelity aerodynamic sub-operators. tool is applied to evaluate the blade wake-inflow pertur- Upper and lower wake inflow dynamics are described in bations, v (r; t), corresponding to harmonic small per- i finite-state form by representing the LTI dynamics of the turbations
Load more

Recommended publications
  • Effectiveness of the Compound Helicopter Configuration in Rotorcraft Performance Increase
    transactions on aerospace research 4(261) 2020, pp.81-106 DOI: 10.2478/tar-2020-0023 eISSN 2545-2835 effectiveness of the compound helicopter configuration in rotorcraft performance increase Jarosław stanisławski Retired doctor of technical sciences [email protected] • ORCID: 0000-0003-1629-4632 abstract The article presents the results of calculations applied to compare flight envelopes of varying helicopter configurations. Performance of conventional helicopter with the main and tail rotors, in the case of compound helicopter, can be improved by applying wings and pusher propellers which generate an additional lift and horizontal thrust. The simplified model of a helicopter structure, consisting of a stiff fuselage and the main rotor treated as a stiff disk, is applied for evaluation of the rotorcraft performance and the required range of control system deflections. The more detailed model of deformable main rotor blades, applying the Galerkin method, is used to calculate rotor loads and blade deformations in defined flight states. The calculations of simulated flight states are performed considering data of a hypothetical medium class helicopter with the take-off mass of 6,000kg. In the case of both of the helicopter configurations, the articulated main rotor hub is taken under consideration. According to the Galerkin method, the elastic blade model allows to compute blade deformations as a combination of the blade bending and torsional eigen modes. Introduction of additional wing and pusher propellers allows to increase the range of operational speed over 300 km/h. Results of the simulation are presented as time- runs of rotor loads and blade deformations and in a form of disk distribution plots of rotor parameters.
    [Show full text]
  • Micro Coaxial Helicopter Controller Design
    Micro Coaxial Helicopter Controller Design A Thesis Submitted to the Faculty of Drexel University by Zelimir Husnic in partial fulfillment of the requirements for the degree of Doctor of Philosophy December 2014 c Copyright 2014 Zelimir Husnic. All Rights Reserved. ii Dedications To my parents and family. iii Acknowledgments There are many people who need to be acknowledged for their involvement in this research and their support for many years. I would like to dedicate my thankfulness to Dr. Bor-Chin Chang, without whom this work would not have started. As an excellent academic advisor, he has always been a helpful and inspiring mentor. Dr. B. C. Chang provided me with guidance and direction. Special thanks goes to Dr. Mishah Salman and Dr. Humayun Kabir for their mentorship and help. I would like to convey thanks to my entire thesis committee: Dr. Chang, Dr. Kwatny, Dr. Yousuff, Dr. Zhou and Dr. Kabir. Above all, I express my sincere thanks to my family for their unconditional love and support. iv v Table of Contents List of Tables ........................................... viii List of Figures .......................................... ix Abstract .............................................. xiii 1. Introduction .......................................... 1 1.1 Vehicles to be Discussed................................... 1 1.2 Coaxial Benefits ....................................... 2 1.3 Motivation .......................................... 3 2. Helicopter Flight Dynamics ................................ 4 2.1 Introduction ........................................
    [Show full text]
  • Open Walsh Thesis.Pdf
    The Pennsylvania State University The Graduate School College of Engineering A PRELIMINARY ACOUSTIC INVESTIGATION OF A COAXIAL HELICOPTER IN HIGH-SPEED FLIGHT A Thesis in Aerospace Engineering by Gregory Walsh c 2016 Gregory Walsh Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science August 2016 The thesis of Gregory Walsh was reviewed and approved∗ by the following: Kenneth S. Brentner Professor of Aerospace Engineering Thesis Advisor Jacob W. Langelaan Associate Professor of Aerospace Engineering George A. Lesieutre Professor of Aerospace Engineering Head of the Department of Aerospace Engineering ∗Signatures are on file in the Graduate School. Abstract The desire for a vertical takeoff and landing (VTOL) aircraft capable of high forward flight speeds is very strong. Compound lift-offset coaxial helicopter designs have been proposed and have demonstrated the ability to fulfill this desire. However, with high forward speeds, noise is an important concern that has yet to be thoroughly addressed with this rotorcraft configuration. This work utilizes a coupling between the Rotorcraft Comprehensive Analysis System (RCAS) and PSU-WOPWOP, to computationally explore the acoustics of a lift-offset coaxial rotor sys- tem. Specifically, unique characteristics of lift-offset coaxial rotor system noise are identified, and design features and trim settings specific to a compound lift-offset coaxial helicopter are considered for noise reduction. At some observer locations, there is constructive interference of the coaxial acoustic pressure pulses, such that the two signals add completely. The locations of these constructive interferences can be altered by modifying the upper-lower rotor blade phasing, providing an overall acoustic benefit.
    [Show full text]
  • Ka-50 Attack Helicopter Acrobatic Flight
    24 EUROPEAL'J ROTORCRAFT FORUM Marseilles, France -15th_l i 11 September 1998 ADOS Ka-50 Attack Helicopter Acrobatic Flight Serguey V. Mikheyev, Boris N. Bourtsev, Serguey V. Selemenev Kamov Company, Moscow Region, Russia I. Introduction The Ka-50 attack helicopter is intended to act against both ground and air targets. High maneuverability of the Ka-50 helicopter provides lower own vulnerability in combat. Aerobatic t1ight demonstrates maneuverability of the helicopter. This is effected by validity of the key solution in the helicopter designing. KAMOV Company helicopter experience concentrates in the Ka-50 attack helicopter. The Table No.1 lists basic types of the serial and experimental helicopters which have been developed by K.AJ\10V Company within the 50 years period. This paper consists of presentations on the following subjects: basic technical solutions and aeroelastic phenomena; examination of test t1ight results; maneuverability features; means of aerobatic t1ight monitoring and analysis. 2.Basic technical solutions and aeroelastic phenomena It is very important to have a substantiation of aeromechanical phenomena. This is feasible given adequate mathematical models making possible to explain and forecast : natural frequencies of structures; loads; aeroelastic stability limits ; helicopter performance . KAL'v!OV Company has developed software to simulate a coaxial rotor aeroelasticity [1,2,4,5]. Aeroelastic phenomena to be simulated are shown in the Fig.2 as ( 1-7) lines in the following way: ( 1) - system of equations of rotor blades motion ; (2) - elastic model of coaxial rotor control linkage ; (3) - model of coaxial rotor vortex wake; (4,5,6)- unsteady aerodynamic data of airfoils; (7) - elastic /mass I geometry data of the upper/lower rotor blades and of the hubs.
    [Show full text]
  • Graduation Project September 2020
    ISTANBUL TECHNICAL UNIVERSITY FACULTY OF AERONAUTICS AND ASTRONAUTICS PERFORMANCE CALCULATION FOR HELICOPTER BLADE UNDER HOVER CONDITION GRADUATION PROJECT Hüseyin DİKEL Department of Aeronautical Engineering Thesis Advisor: Assis. Prof. Dr. Özge ÖZDEMİR SEPTEMBER 2020 i ISTANBUL TECHNICAL UNIVERSITY FACULTY OF AERONAUTICS AND ASTRONAUTICS PERFORMANCE CALCULATION FOR HELICOPTER BLADE UNDER HOVER CONDITION GRADUATION PROJECT Hüseyin DİKEL (110150005) Department of Aeronautıcal Engineering Thesis Advisor: Assis. Prof. Dr. Özge ÖZDEMİR SEPTEMBER 2020 iii Hüseyin DİKEL, student of ITU Faculty of Aeronautics and Astronautics student ID 110150005, successfully defended the graduation entitled “PERFORMANCE CALCULATION FOR HELICOPTER BLADE UNDER HOVER CONDITION” which he prepared after fulfilling the requirements specified in the associated legislations, before the jury whose signatures are below. Thesis Advisor: Assis. Prof. Dr. Özge ÖZDEMİR .............................. İstanbul Technical University Jury Members: Prof. Dr. Metin Orhan KAYA ............................... İstanbul Technical University Prof. Dr. Zahit MECİTOĞLU ............................... İstanbul Technical University Date of Submission : 07 September 2020 Date of Defense : 14 September 2020 v To my big family, iii iv FOREWORD Önsöz bölümünün içerisindeki metinler 1 satır aralıklı yazılır. Tezin ilk sayfası niteliğinde yazılan önsöz ikisayfayı geçmez. Tezi destekleyen kurumlara ve yardımcı olan kişilere bu kısımdateşekkür edilir. Önsöz metninin altında sağa dayalı olarak
    [Show full text]
  • Rotor Diameter
    Scaling Up Success The SB>1 Defiant Joint Multi-Role Technology Demonstrator challenges Sikorsky and Boeing to grow the integrated X2 technologies By Frank Colucci peed and range improvements The SB>1 Defiant JMR Technology Demonstrator scales up Sikorsky X2 rigid coaxial rotor sought by US Army Aviation drove compound helicopter technologies to achieve speed, range and agility far better than SSikorsky, Boeing and their Defiant conventional helicopters. (Sikorsky graphic) team to scale up technologies flown on the 6,000 lb (3 t) X2 and 11,400 lb The MPS summary of FVL-M teams, Sikorsky Innovations vice (5.2 t) S-97 to the 30,000 lb (14 t) class performance includes cruising president Chris Van Buiten previously SB>1 Joint Multi-Role Technology speeds greater than 230 kt (426 stated, “Raider is risk-reduction for JMR.” Demonstrator (JMR-TD). A Systems km/h), vertical takeoff at 6,000 ft/95˚F Sikorsky and Boeing teamed Integration Laboratory (SIL) for Defiant (1,800 m/35˚C) density altitude and up on the SB>1 Defiant in January came on line in December and a a combat radius of 229 nm (424 km) 2013. Boeing program co-director Transmission System Test Bed will run with four crew and 12 troops. The 250 Pat Donnelly said, “When we put in 2016. The JMR-TD due to fly in 2017 is kt (463 km/h) Defiant answers the this together, we were certainly very based on a 2013 Mission Performance specification with rigid coaxial rotors, sensitive to the scaling issues of the Specification (MPS) for a medium-size an integrated tail propeller, optimized X2 technology.
    [Show full text]
  • Helicopter Society (AHS) International STEM Committee: Free to Distribute with Attribution History of Rotorcraft
    History and Overview of Rotating Wing Aircraft Photo by Paolo Rosa Produced by the American Helicopter Society (AHS) International STEM Committee: www.vtol.org/stem Free to distribute with attribution History of Rotorcraft • Definition of Rotorcraft – Any flying machine using rotating wings to provide lift, propulsion, and control that enable vertical flight and hover Rotating wings provide propulsion, Rotating wings provide lift, but negligible lift and control. propulsion, control at same time. History of Rotorcraft • Two key configurations developed in parallel – Autogiro • Close to helicopter, uses many of same mechanical feature • Cannot hover • Unpowered rotor – Helicopter • Powered rotor • Many configurations have been developed • Autogiros flew first! – Autogiro innovations enabled development of first helicopters Autogyro – How it Works Lift Unpowered Rotor that Spins Due to Wind Blowing Through Rotor Like a Wind Turbine Relative Wind No Need for Anti-Torque Since Not Driven Thrust By an Engine Fixed to the Fuselage Control Surfaces Autogyro – How it Works Kind of like parasailing, except rotor provides lift in addition to drag. Helicopter – How it Works • Powered Rotor • Equal and opposite torque applied to rotor acts on fuselage Tail Rotor Rotor Thrust Thrust Main Rotor Drive Shaft Tail Boom Cockpit Tail Rotor Engine, Fuel, Landing Skids Transmission, etc. Controls Helicopter – Need for Anti-Torque • Engine fixed on body – exerts torque on rotor shaft – Rotor shaft exerts equal and opposite torque on body • Many configurations
    [Show full text]
  • Odyssey” Multi-Mission Aircraft
    GRADUATE DESIGN REPORT GEORGIA INSTITUTE OF TECHNOLOGY 28TH ANNUAL AHS STUDENT DESIGN COMPETITION 2011 Sylvester Ashok Raymond Beale Bhanu Chiguluri Michael Jones Jeewoong Kim Jonathan Litwin Marc Mugnier 2011 AHS Student Design Competition Jaikrishnan Vijayakumari Graduate Category Xin Zhang “ODYSSEY” MULTI-MISSION AIRCRAFT DEPARTMENT OF AEROSPACE ENGINEERING GEORGIA INSTITUTE OF TECHNOLOGY ATLANTA, GA, 30332 AND UNIVERSITY OF LIVERPOOL 28TH ANNUAL AMERICAN HELICOPTER SOCIETY STUDENT DESIGN COMPETITION GRADUATE CATEGORY Sylvester Ashok PhD Candidate Jonathan Litwin - Undergraduate Student [email protected] AE 4359 – Rotorcraft Design II [email protected] Raymond Beale - Graduate Student Marc Mugnier - Graduate Student (Team leader) AE 8900 – Special Problem AE 8900 – Special Problem [email protected] [email protected] Bhanu Chiguluri - Undergraduate Student Jaikrishnan Vijaykumar – Graduate Student AE 4359 – Rotorcraft Design II AE 6334 – Rotorcraft Design II [email protected] [email protected] Michael Jones – PhD Candidate Xin Zhang – PhD Candidate (University of Liverpool) AE 6334 – Rotorcraft Design II [email protected] [email protected] Jeewoong Kim - Graduate Student Dr. Daniel P. Schrage – Principal Advisor and Instructor AE 6334 – Rotorcraft Design II AE 6334 – Rotorcraft Design II (SPRING 11) [email protected] [email protected] 2011 AHS Student Design Competition ii Graduate Category Acknowledgements The Odyssey design team would like to acknowledge the following people and thank them for their assistance and advice during the entire project: Dr Daniel P. Schrage – Professor, Department of Aerospace Engineering, Georgia Institute of Technology Dr Dimitri N. Mavris – Director of ASDL, Department of Aerospace Engineering, Georgia Institute of Technology Dr Lakshmi Sankar – Regents Professor, Department of Aerospace Engineering, Georgia Institute of Technology Dr.
    [Show full text]
  • A Comparison of Coaxial and Conventional Rotor Performance
    JOURNAL OF THE AMERICAN HELICOPTER SOCIETY 55, 012004 (2010) A Comparison of Coaxial and Conventional Rotor Performance Hyo Won Kim1 Richard E. Brown∗ Postgraduate Research Student Mechan Chair of Engineering Department of Aeronautics Department of Aerospace Engineering Imperial College London University of Glasgow London, UK Glasgow, UK The performance of a coaxial rotor in hover, in steady forward flight, and in level, coordinated turns is contrasted with that of an equivalent, conventional rotor with the same overall solidity, number of blades, and blade aerodynamic properties. Brown’s vorticity transport model is used to calculate the profile, induced, and parasite contributions to the overall power consumed by the two systems, and the highly resolved representation of the rotor wake that is produced by the model is used to relate the observed differences in the performance of the two systems to the structures of their respective wakes. In all flight conditions, all else being equal, the coaxial system requires less induced power than the conventional system. In hover, the conventional rotor consumes increasingly more induced power than the coaxial rotor as thrust is increased. In forward flight, the relative advantage of the coaxial configuration is particularly evident at pretransitional advance ratios. In turning flight, the benefits of the coaxial rotor are seen at all load factors. The beneficial properties of the coaxial rotor in forward flight and maneuver, as far as induced power is concerned, are a subtle effect of rotor–wake interaction and result principally from differences between the two types of rotor in the character and strength of the localized interaction between the developing supervortices and the highly loaded blade-tips at the lateral extremities of the rotor.
    [Show full text]
  • Modeling and Simulation of Coaxial Helicopter Rotor Aerodynamics
    Old Dominion University ODU Digital Commons Mechanical & Aerospace Engineering Theses & Dissertations Mechanical & Aerospace Engineering Winter 2009 Modeling and Simulation of Coaxial Helicopter Rotor Aerodynamics Murat Gecgel Old Dominion University Follow this and additional works at: https://digitalcommons.odu.edu/mae_etds Part of the Aerodynamics and Fluid Mechanics Commons Recommended Citation Gecgel, Murat. "Modeling and Simulation of Coaxial Helicopter Rotor Aerodynamics" (2009). Doctor of Philosophy (PhD), Dissertation, Mechanical & Aerospace Engineering, Old Dominion University, DOI: 10.25777/n6nw-ng82 https://digitalcommons.odu.edu/mae_etds/53 This Dissertation is brought to you for free and open access by the Mechanical & Aerospace Engineering at ODU Digital Commons. It has been accepted for inclusion in Mechanical & Aerospace Engineering Theses & Dissertations by an authorized administrator of ODU Digital Commons. For more information, please contact [email protected]. MODELING AND SIMULATION OF COAXIAL HELICOPTER ROTOR AERODYNAMICS by Murat Gecgel B.S. August 1995, Turkish Air Force Academy, Turkey M.S. September 2003, Middle East Technical University, Turkey A Dissertation Submitted to the Faculty of Old Dominion University in Partial Fulfillment of the Requirement for the Degree of DOCTOR OF PHILOSOPHY AEROSPACE ENGINEERING OLD DOMINION UNIVERSITY December 2009 Approved by: Dr.Oktay Baysal (Director) Dr.Osama Kandil (Member) Dr.Ali Beskok (Member) Dr.Abdurrahman Hacioglu (Member) II ABSTRACT MODELING AND SIMULATION OF COAXIAL HELICOPTER ROTOR AERODYNAMICS Murat Gecgel Old Dominion University, 2009 Director: Dr. Oktay Baysal A framework is developed for the computational fluid dynamics (CFD) analyses of a series of helicopter rotor flowfields in hover and in forward flight. The methodology is based on the unsteady solutions of the three-dimensional, compressible Navier-Stokes equations recast in a rotating frame of reference.
    [Show full text]
  • High-Speed Unmanned Octo-Rotor Helicopters
    Asian Journal of Natural & Applied Sciences Vol. 3(3) September 2014 _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________ High-Speed Unmanned Octo-Rotor Helicopters Svetoslav Zabunov 1, Petar Getsov 2, Garo Mardirossian 3 Space Research and Technology Institute at the Bulgarian Academy of Sciences, BULGARIA. 1 [email protected]
    [Show full text]
  • Study of Contra-Rotating Coaxial Rotors in Hover, a Performance Model Based on Blade Element Theory Including Swirl Velocity
    Theses - Daytona Beach Dissertations and Theses Fall 2007 Study of Contra-rotating Coaxial Rotors in Hover, A Performance Model Based on Blade Element Theory Including Swirl Velocity Florent Lucas Embry-Riddle Aeronautical University - Daytona Beach Follow this and additional works at: https://commons.erau.edu/db-theses Part of the Aerospace Engineering Commons Scholarly Commons Citation Lucas, Florent, "Study of Contra-rotating Coaxial Rotors in Hover, A Performance Model Based on Blade Element Theory Including Swirl Velocity" (2007). Theses - Daytona Beach. 127. https://commons.erau.edu/db-theses/127 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]. STUDY OF COUNTER-ROTATING COAXIAL ROTORS IN HOVER A PERFORMANCE MODEL BASED ON BLADE ELEMENT THEORY INCLUDING SWIRL VELOCITY by Florent Lucas A thesis submitted to the Aerospace Engineering Department In Partial Fulfilment of the Requirements for the Degree of Master of Science in Aerospace Engineering Embry-Riddle Aeronautical University Daytona Beach, Florida Fall 2007 UMI Number: EP32005 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]