Scholars@Duke
Jeffrey P. Thomas

Jeffrey P. Thomas

Assistant Research Professor in the Thomas Lord Department of Mechanical Engineering and Materials Science
Thomas Lord Department of Mechanical Engineering and Materials Science
jthomas@duke.edu
Box 90300, Durham, NC 27708-0300
237 Hudson Eng Ctr, Durham, NC

Selected Publications

Aeroelastic Flap Free-Play Analysis Using a Harmonic Balance Approach

Conference AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025 · January 1, 2025 Aeroelastic limit cycle oscillation results are presented for a three-degree-of-freedom plunge, pitch, and flap structural model with flap free-play in a viscous transonic flow airfoil. A nonlinear frequency domain harmonic balance approach is used for the ... Full text Cite

Stall Flutter of the Benchmark Supercritical Wing Using Aeroelastic Model Reduction and Tunable Turbulence Parameters

Conference AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025 · January 1, 2025 This paper investigates the flutter mechanism of the benchmark supercritical wing at Mach 0.8 with the angle-of-attack (AOA) at 1◦, 3◦ and 5◦. Nonlinear unsteady aerodynamic reduced order models (ROMs) are used which are trained using data obtained from UR ... Full text Cite

Using Broyden’s Method to Improve the Computational Performance of a Harmonic Balance Aeroelastic Solution Technique

Conference AIAA SciTech Forum and Exposition, 2023 · January 1, 2023 Presented is a technique that significantly improves the computational performance of an existing harmonic balance-based flutter onset and limit-cycle oscillation aeroelastic solution methodology. The existing harmonic balance aeroelastic solution methodol ... Full text Cite

Convolution/Volterra Reduced-Order Modeling for Nonlinear Aeroelastic Limit Cycle Oscillation Analysis and Control

Journal Article AIAA Journal · December 1, 2022 A methodology for leveraging a combination of linear (through convolution integrals) and nonlinear (through Volterra series) reduced-order modeling (ROM) development was demonstrated on both a two-and three-degree-of-freedom (2-DOF and 3-DOF, respectively) ... Full text Cite

Convolution/Volterra Reduced-Order Modeling for Flutter and LCO Predictions in Highly Nonlinear Systems

Conference AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 · January 1, 2022 A methodology for leveraging a combination of linear (through convolution integrals) and nonlinear (through Volterra series) reduced-order modeling (ROM) development was demonstrated on both a 2 and 3 degree of freedom (DOF) aeroelastic system. The linear/ ... Full text Cite

Non-Intrusive Polynomial Chaos Approach for Nonlinear Aeroelastic Uncertainty Quantification

Conference AIAA AVIATION 2022 Forum · January 1, 2022 Presented is a point collocation non-intrusive polynomial chaos approach for nonlinear aeroelastic uncertainty quantification analysis. A unique aspect of our approach is that we are using a nonlinear frequency-domain harmonic balance aeroelastic solution ... Full text Cite

Automatic differentiation based nonlinear reduced-order model with geometric gradient computation capability

Conference AIAA Scitech 2021 Forum · January 1, 2021 Presented is an automatic differentiation based nonlinear reduced-order modeling technique which includes geometric variation computation capability. The method is based on a Taylor series expansion of a nonlinear frequency-domain harmonic balance based co ... Cite

Nonlinear Aeroelastic Reduced-Order Modeling Approach with Geometric Gradient Computation Capability

Conference AIAA Aviation and Aeronautics Forum and Exposition, AIAA AVIATION Forum 2021 · January 1, 2021 We have recently developed an automatic differentiation based nonlinear reduced-order modeling technique. The method is based on a Taylor series expansion of a nonlinear frequencydomain harmonic balance based computational fluid dynamic solver residual. In ... Full text Cite

Methodology for numerically stabilizing a harmonic balance based aeroelastic solution approach

Conference AIAA Scitech 2020 Forum · January 1, 2020 Presented is a methodology for numerically stabilizing harmonic balance based aeroelastic solution approaches. The governing harmonic balance based aeroelastic equations are a stationary/steady system of equations. In order to solve these equations, many r ... Full text Cite

Discrete adjoint constrained design optimization approach for unsteady transonic aeroelasticity and buffet

Conference AIAA AVIATION 2020 FORUM · January 1, 2020 We present the details of two primary research topics in the area of aeroelastic optimization that we are currently working on. The first topic is a new discrete adjoint aeroelastic design optimization solution methodology, which has a computational cost t ... Full text Cite

Progress toward efficient compression algorithms for application in flight simulation environments

Conference Journal of Aerospace Information Systems · January 1, 2019 Modern computational fluid dynamic simulations of flows about naval vessels produce an enormous amount of flow-field data. The computations are performed in order to model details of the erratic unsteady flows that can occur about naval superstructures. Th ... Full text Cite

Discrete adjoint approach for nonlinear unsteady aeroelastic design optimization

Journal Article AIAA Journal · January 1, 2019 Presented is a discrete adjoint approach for computing nonlinear unsteady aeroelastic geometric design sensitivities, which can subsequently be used for nonlinear unsteady aeroelastic geometric design optimization. The methodology is applicable to compress ... Full text Cite

Flutter prediction based on dynamic eigen decomposition of coupled CFD-CSD flight simulation

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 © Universal Technology Corporation, 2018. During the design and analysis of aircraft flutter boundaries are typically computed using the p-k iterations, k iterations, p iterations, or eigenvalue analysis, that require computationally expensive and numerica ... Cite

Flutter prediction based on dynamic eigen decomposition of coupled CFD-CSD flight simulation

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 During the design and analysis of aircraft flutter boundaries are typically computed using the p-k iterations, k iterations, p iterations, or eigenvalue analysis, that require computationally expensive and numerically sensitive procedures especially for co ... Cite

Aeroelastic analysis of a wind turbine blade using the harmonic balance method

Journal Article Wind Energy · April 1, 2018 An aeroelastic model for wind turbine blades derived from the unsteady Navier-Stokes equations and a mode shape–based structural dynamics model are presented. For turbulent flows, the system is closed with the Spalart-Allmaras turbulence model. The computa ... Cite

A fixed point iteration approach for harmonic balance based aeroelastic computations

Conference AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2018 · January 1, 2018 Presented is a fixed point iteration approach for harmonic balance computational flow solver based nonlinear aeroelastic computations. The methodology allows for the aeroelastic governing equations to be solved simultaneously, in an iterative manner, along ... Full text Cite

Progress toward efficient compression algorithms for application in flight simulation environments

Conference 2018 Modeling and Simulation Technologies Conference · January 1, 2018 In the following paper, we demonstrate the use of both proper orthogonal decomposition and Fourier series decomposition approaches for airwake dataset compression. The proper orthogonal decomposition method is used for compressing airwake data in the time- ... Full text Cite

An aeroelastic model for vortex-induced vibrating cylinders subject to frequency lock-in

Journal Article Journal of Fluids and Structures · February 1, 2016 This work presents a novel way to calculate the response amplitude of an elastically supported cylinder experiencing vortex-induced vibrations. The method couples a computational fluid dynamic (CFD) model of the shedding vortex flow to a structural model r ... Full text Cite

Vortex-Induced Vibration and Frequency Lock-In of an Airfoil at High Angles of Attack

Journal Article Journal of Fluids Engineering, Transactions of the ASME · January 1, 2016 Vortex-induced vibration is a fluid instability where vortices due to secondary flows exert a periodic unsteady force on the elastic structure. Under certain circumstances, the shedding frequency can lock into the structure natural frequency and lead to li ... Full text Cite

Store-induced limit-cycle oscillations due to nonlinear wing-store attachment

Journal Article Journal of Aircraft · January 1, 2016 Several high-performance fighter aircraft exhibit store-induced limit-cycle oscillations, leading to pilot discomfort, potential structural fatigue, and flight envelope restrictions. The roles of various aerodynamic and structural factors causing the limit ... Full text Cite

Developing a reduced-order model of nonsynchronous vibration in turbomachinery using proper-orthogonal decomposition methods

Journal Article Journal of Engineering for Gas Turbines and Power · May 1, 2015 The paper develops a reduced-order model of nonsynchronous vibration (NSV) using proper orthogonal decomposition (POD) methods. The approach was successfully developed and implemented, requiring between two and six POD modes to accurately predict computati ... Full text Cite

Progress on a wind turbine aeroelastic solution methodology using harmonic balance

Conference 33rd Wind Energy Symposium · January 1, 2015 Steps taken to develop aeroelastic modeling of wind turbine blades derived from the unsteady Navier-Stokes equations and a mode shape-based structural dynamics model are presented. For turbulent flows, the system is closed with the Spalart-Allmaras turbule ... Cite

Discrete adjoint design optimization approach for increasing transonic buffet onset angle-of-attack

Conference 16th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2015 © 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All rigths reserved. Presented is a discrete adjoint method for transonic buffet design optimization. The method is based on a frequency do-main approach for modeling unsteady aerodynami ... Cite

Discrete adjoint design optimization approach for increasing transonic buffet onset angle-of-attack

Conference 16th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2015 Presented is a discrete adjoint method for transonic buffet design optimization. The method is based on a frequency do-main approach for modeling unsteady aerodynamics. Automatic differentiation is used to derive the computer code representing the adjoint ... Full text Cite

Discrete adjoint approach for aeroelastic design optimization

Conference AIAA AVIATION 2014 -15th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2014 Using aeroelastic flutter geometric design sensitivities provided by a recently developed discrete adjoint aeroelastic solver, the shape of a NLR 7301 airfoil section is optimized to increase flutter onset velocity for a benchmark transonic aeroelastic con ... Cite

Vortex-induced vibration and frequency lock-in of an airfoil at high angles of attack

Conference Proceedings of the ASME Turbo Expo · January 1, 2014 Vortex-induced vibration is a fluid instability present in many areas, including offshore platforms, wind turbines, and turbomachinery. The vortices due to secondary flows exert an periodic unsteady force on the elastic structure, leading to potentially da ... Full text Cite

Developing a reduced-order model of non-synchronous vibration in turbomachinery using proper-orthogonal decomposition methods

Conference Proceedings of the ASME Turbo Expo · January 1, 2014 The paper develops a reduced-order model of nonsynchronous vibration (NSV) using proper orthogonal decomposition (POD) methods. The approach was successfully developed and implemented, requiring between two and six POD modes to accurately predict CFD solut ... Full text Cite

Discrete adjoint method for nonlinear aeroelastic sensitivities for compressible and viscous flows

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · August 15, 2013 Presented is a discrete adjoint approach for computing nonlinear aeroelastic design sensitivities for transonic and viscous flows based on Reynolds Averaged Navier-Stokes computational fluid dynamic models. The method is based on a harmonic balance nonline ... Cite

Discrete adjoint method for nonlinear aeroelastic sensitivities for compressible and viscous flows

Conference 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · August 2, 2013 Presented is a discrete adjoint approach for computing nonlinear aeroelastic design sensitivities for transonic and viscous flows based on Reynolds Averaged Navier-Stokes computational fluid dynamic models. The method is based on a harmonic balance nonline ... Full text Cite

Compact implementation strategy for a harmonic balance method within implicit flow solvers

Journal Article AIAA Journal · June 1, 2013 A two-step approximate factorization technique for implementing a computationally stable nonlinear unsteady frequency-domain harmonic balance solution method within existing implicit computational fluid dynamic flow solver codes is presented. The approach ... Full text Cite

Stabilization of explicit flow solvers using a proper-orthogonal- decomposition technique

Conference AIAA Journal · May 1, 2013 A new numerical technique for the stabilization of explicit computational-fluid-dynamic solvers is presented. When using computational-fluid-dynamic codes to solve practical problems one sometimes finds the solution fails to converge due to the presence of ... Full text Cite

Harmonic balance methods applied to computational fluid dynamics problems

Journal Article International Journal of Computational Fluid Dynamics · February 1, 2013 In this paper, we briefly review the classical harmonic balance method, and describe the adaptation of the method required for its application to computational fluid dynamics models of unsteady time periodic flows. We describe several variations of the met ... Full text Cite

An automatic differentiation based nonlinear reduced order modeling technique for unsteady separated flows

Conference 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition · December 1, 2012 This paper discusses the development and implementation of an automatic differentiation based nonlinear reduced order model for unsteady separated flows. The objective of the research presented herein has been to test the capability and limits of the metho ... Full text Cite

Stabilization of explicit flow solvers using a proper orthogonal decomposition technique

Conference 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition · December 1, 2012 A new numerical technique for the stabilization of explicit computational fluid dynamic (CFD) solvers is presented. When using CFD codes to solve practical problems, one sometimes finds the solution fails to converge due to the presence of a small number o ... Full text Cite

Airfoil transonic flow buffet calculations using the OVERFLOW 2 flow solver

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2011 An investigation of modeling unsteady transonic buffeting flow for the NACA 0012 airfoil when using the NASA OVERFLOW 2 flow solver code is presented. For a fixed freestream Mach number and Reynolds number, buffeting flow is modeled for various angles-of-a ... Full text Cite

Toward a high order throughflow - investigation of the nonlinear harmonic method coupled with an immersed boundary method for the modeling of the circumferential stresses

Journal Article Journal of Turbomachinery · May 31, 2011 Capturing a level of modeling of the flow inside a multistage turbomachine, such as unsteadiness for example, can be done at different levels of detail, either by capturing all deterministic features of the flow with a pure unsteady method or by settling f ... Full text Cite

F-16 fighter aeroelastic computations using a harmonic balance implementation of the OVERFLOW 2 flow solver

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 16, 2010 Presented are flutter-onset trends of the F-16 fighter computed using a harmonic balance version of the NASA OVERFLOW 2 flow solver code. The harmonic technique enables one to model unsteady aerodynamics and aeroelastic response in the frequency domain wit ... Cite

Towards a high order throughflow. Part I: Investigating the effectiveness of a harmonic reconstruction for 3D flows

Conference Proceedings of the ASME Turbo Expo · December 1, 2010 The computation time and the extraction of useful information remain severe drawbacks to systematic use of modern three-dimensional Navier-Stokes codes in a design procedure of multistage turbomachines. That explains why throughflow simulation is still wid ... Full text Cite

Towards a high order throughflow. Part II: Investigation of the nonlinear harmonic method coupled with an immersed boundary method for the modeling of the circumferential stresses

Conference Proceedings of the ASME Turbo Expo · December 1, 2010 Capturing a level of modeling of the flow inside a multi-stage turbomachine, such as unsteadiness for example, can be done at different degrees of details, either by capturing all deterministic features of the flow with a pure unsteady method or by settlin ... Full text Cite

Using automatic differentiation to create a nonlinear reduced-order-model aerodynamic solver

Journal Article AIAA Journal · January 1, 2010 A novel nonlinear reduced-order-modeling technique for computational aerodynamics and aeroelasticity is presented. The method is based on a Taylor series expansion of a frequency-domain harmonic balance computational fluid dynamic solver residual. The firs ... Full text Cite

Preliminary flutter design method for supersonic low pressure turbines

Journal Article Proceedings of the ASME Turbo Expo · December 1, 2009 The "Tie-Dye" (TD) method is a well-known preliminary flutter design method for subsonic low pressure turbine (LPT) blades. In this paper, a study of 2D mode shape sensitivity using the TD-method for supersonic exit Mach numbers is presented. Using a harmo ... Full text Cite

On the role of the deterministic and circumferential stresses in throughflow calculations

Journal Article Journal of Turbomachinery · July 1, 2009 This paper presents a throughflow analysis tool developed in the context of the averagepassage flow model elaborated by Adamczyk. The Adamczyk's flow model describes the 3D time-averaged flow field within a blade row passage. The set of equations that gove ... Full text Cite

Erosion Resistant Coatings for Aircraft Engines

Journal Article Vakuum in Forschung und Praxis · June 1, 2009 Under certain operation conditions, increased amounts of sand particles may be injected into the air inlet duct of jet engines. Because of the high air speed and the high velocity of the compressor blades, an intense material emoval from the airfoils by er ... Full text Cite

Ten years of experience with a small jet engine as a support for education

Journal Article Journal of Engineering for Gas Turbines and Power · January 1, 2009 In 1997 the Turbomachinery Group of the University of Liège decided to acquire a small jet engine to illustrate the courses in propulsion and to provide the students with the opportunity to get some experience on data measurement, acquisition, and interpre ... Full text Cite

Improved flutter boundary prediction for an isolated two-degree-of-freedom airfoil

Journal Article Journal of Aircraft · January 1, 2009 A novel method of computing the flutter boundary for an isolated airfoil based on a high-fidelity computational fluid dynamics model reveals unusual behavior in a critical transonic range. Inviscid and viscous predictions of the flutter boundary for the tw ... Full text Cite

Theoretical predictions of F-16 fighter limit cycle oscillations for flight flutter testing

Journal Article Journal of Aircraft · January 1, 2009 A computational investigation of the flutter onset and limit cycle oscillation behavior of various F-16 fighter weapons and stores configurations is presented. A nonlinear harmonic balance compressible Reynolds-averaged Navier-Stokes computational fluid dy ... Full text Cite

Unsteady flow computation using a harmonic balance approach implemented about the OVERFLOW 2 flow solver

Conference 19th AIAA Computational Fluid Dynamics Conference · January 1, 2009 A novel approach for implementing a nonlinear unsteady frequency domain harmonic balance solution technique about existing implicit computational fluid dynamic flow solvers is presented. This approach uses an explicit discretization of the harmonic balance ... Full text Cite

Application of enforced motion to study 2-D cascade lock-in effect

Conference 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition · January 1, 2009 The vortex lock-in effect has been well-studied for an oscillating cylinder and numerous experimental and computational data are available. However, only recently has this phenomenon been observed for two-dimensional isolated airfoils as well as turbine ca ... Full text Cite

Ten years of experience with a small jet engine as a support for education

Conference Proceedings of the ASME Turbo Expo · December 1, 2008 In 1997 the Turbomachinery group of the University of Liège decided to acquire a small jet engine to illustrate the courses in propulsion and to provide the students with the opportunity to get some experience in data measurement, acquisition and interpret ... Full text Cite

Investigating circumferential non-uniformities in throughflow calculations using an harmonic reconstruction

Conference Proceedings of the ASME Turbo Expo · December 1, 2008 The computation time and the extraction of useful information remain severe drawbacks to systematic use of modern three-dimensional Navier-Stokes codes in a design procedure of multistage turbomachines. That explains why throughflow simulation is still wid ... Full text Cite

Efficient design method for non-synchronous vibrations using enforced motion

Conference Proceedings of the ASME Turbo Expo · December 1, 2008 This paper presents the results of a new enforced motion method using harmonic balance computational fluid dynamics (CFD) analysis to design for NSV. Currently, most researchers employ a time domain CFD technique to directly find the frequency of the under ... Full text Cite

Reduced order models in unsteady aerodynamic models, aeroelasticity and molecular dynamics

Conference ICAS Secretariat - 26th Congress of International Council of the Aeronautical Sciences 2008, ICAS 2008 · December 1, 2008 The state of reduced order modeling of unsteady aerodynamic flows for the efficient calculation of fluid-structure interaction (aeroelasticity) is discussed as well as very recent work on olecular dynamics simulations. Starting with either a time domain or ... Cite

A new solution method for unsteady flows around oscillating bluff bodies

Journal Article Solid Mechanics and its Applications · January 1, 2008 Full text Cite

Fan flutter computations using the harmonic balance method

Journal Article 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2008 An experimental forward-swept fan encountered flutter at part-speed conditions during wind tunnel testing. A new propulsion aeroelasticity code, based on a computational fluid dynamics (CFD) approach, was used to model the aeroelastic behavior of this fan. ... Full text Cite

Virtual aeroelastic flight testing for the F-16 fighter with stores

Conference Collection of Technical Papers - U.S. Air Force T and E Days, 2007(Test and Evaluation · November 5, 2007 In the following, we present computational aeroelastic flutter onset and limit cycle oscillation response trends for various stores and weapons configurations of the F-16 fighter. A nonlinear harmonic balance compressible Reynolds averaged Navier-Stokes co ... Cite

A high dimensional harmonic balance approach for an aeroelastic airfoil with cubic restoring forces

Journal Article Journal of Fluids and Structures · April 1, 2007 This is a study of a two-dimensional airfoil including a cubic spring stiffness placed in an incompressible flow. A new formulation of the harmonic balance method is employed for the aeroelastic airfoil to investigate the amplitude and frequency of the lim ... Full text Cite

An investigation of the sensitivity of F-16 fighter flutter onset and limit cycle oscillations to uncertainties

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2006 A computational investigation of flutter onset and limit cycle oscillations of the F-16 fighter using a nonlinear frequency-domain harmonic-balance approach is presented. In this latest study, we examine the sensitivity of computed aeroelastic behavior to ... Cite

Reduced order nonlinear system identification methodology

Journal Article AIAA Journal · August 1, 2006 A new method is presented which enables the identification of a reduced order nonlinear ordinary differential equation (ODE) which can be used to model the behavior of nonlinear fluid dynamics. The method uses a harmonic balance technique and proper orthog ... Full text Cite

A comparison of classical and high dimensional harmonic balance approaches for a Duffing oscillator

Journal Article J. Comput. Phys. (USA) · 2006 The present study focuses on a novel harmonic balance formulation, which is much easier to implement than the standard/classical harmonic balance method for complex nonlinear mathematical models and algorithms. Both harmonic balance approaches are applied ... Full text Link to item Cite

Static/dynamic correction approach for reduced-order modeling of unsteady aerodynamics

Journal Article Journal of Aircraft · 2006 Presented is a newly devised static/dynamic correction approach for eigenvector expansion based reduced-order modeling (ROM). When compared to the fundamental Ritz ROM formulation, along with the static and multiple static correction ROM approaches, the te ... Cite

Modeling cylinder flow vortex shedding with enforced motion using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2006 In recent years, new aeromechanical problems have been encountered in turbomachinery. In particular, non-synchronous vibrations (NSV) in blades have been observed by engine companies and occur as a result of flow instabilities. As a first step towards bett ... Full text Cite

Using automatic differentiation to create a nonlinear reduced order model of a computational fluid dynamic solver

Conference Collection of Technical Papers - 11th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2006 Presented is a technique for developing a nonlinear reduced order model of a computational fluid dynamic solver. The method is based on a Taylor series expansion of a frequency domain harmonic balance computational fluid dynamic solver residual. The comput ... Full text Cite

Further investigation of modeling limit cycle oscillation behavior of the F-16 fighter using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 19, 2005 A computational investigation of limit cycle oscillation behavior of the F-16 fighter configuration using a nonlinear frequency-domain harmonic-balance approach is presented. The research discussed in this latest paper is a follow-on to our work presented ... Cite

Reduced order unsteady aerodynamic models and aeroelasticity

Conference 12th International Congress on Sound and Vibration 2005, ICSV 2005 · December 1, 2005 The state of reduced order modeling of unsteady aerodynamic flows for the efficient calculation of fluid-structure interaction (aeroelasticity) is discussed. Reduced order modeling is a set of conceptually novel and computationally efficient techniques for ... Cite

Discrete adjoint approach for modeling unsteady aerodynamic design sensitivities

Journal Article AIAA Journal · 2005 A discrete adjoint approach is presented for computing steady and unsteady aerodynamic design sensitivities for compressible viscous flows about airfoil configurations. The nominal flow solver method is based on a harmonic balance solution technique, which ... Cite

Computational models for nonlinear aeroelasticity

Conference 43rd AIAA Aerospace Sciences Meeting and Exhibit - Meeting Papers · January 1, 2005 Two distinctly different reduced-order models are formulated for fully nonlinear aeroelastic systems. The first is based on Proper Orthogonal Decomposition (POD). The velocity field is decomposed into a finite number of orthonormal modes, effecting order r ... Full text Cite

Higher order harmonic balance analysis for limit cycle oscillations in an airfoil with cubic restoring forces

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2005 This is a study of a two dimensional airfoil including a cubic spring stiffness placed in an incompressible flow. A new formulation of the harmonic balance method is employed for the aeroelastic airfoil to investigate the amplitude and frequency of the lim ... Full text Cite

Recent advancements in turbomachinery aeroelastic design analysis

Conference 43rd AIAA Aerospace Sciences Meeting and Exhibit - Meeting Papers · January 1, 2005 In this paper, we review some recent developments for computing unsteady aerodynamic loads associated with turbomachinery aeromechanics. In particular, we example the use of frequency domain techniques for computing unsteady flows in turbomachinery. The fr ... Full text Cite

Modeling limit cycle oscillation behavior of the F-16 fighter using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2004 A computational investigation of limit cycle oscillation behavior of the F-16 fighter configuration using a nonlinear frequency-domain harmonic-balance approach is presented. Computed limit cycle response results correlate well with experiment. Details of ... Cite

Limit-cycle oscillations of a typical airfoil in transonic flow

Journal Article Journal of Aircraft · 2004 Using an inviscid flow computational-fluid-dynamic model and a harmonic balance flow solver, a parametric investigation of how structural-inertial parameters and freestream Mach number of a transonic flow affect the limit-cycle oscillation characteristics ... Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Journal Article Journal of Fluids and Structures · 2004 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Full text Link to item Cite

Modeling viscous transonic limit-cycle oscillation behavior using a harmonic balance approach

Journal Article Journal of Aircraft · 2004 Presented is a harmonic-balance computational fluid dynamic approach for modeling limit-cycle oscillation behavior of aeroelastic airfoil configurations in a viscous transonic flow. For the NLR 7301 airfoil configuration studied, accounting for viscous eff ... Cite

Improved understanding of transonic flutter: A three-parameter flutter surface

Journal Article Journal of Aircraft · 2004 An understanding of transonic flutter is often critical for high-speed aircraft development. A presentation of the transonic flutter velocity as a function of the Mach number and mass ratio is shown here to provide many advantages. Such a presentation offe ... Cite

Frequency domain techniques for complex and nonlinear flows in turbomachinery

Conference 33rd AIAA Fluid Dynamics Conference and Exhibit · December 1, 2003 In this paper, we review frequency domain techniques for computing unsteady flows in turbomachinery. The frequency domain approaches, which can be used to model both small-disturbance and nonlinear time periodic flows, are computationally very efficient, t ... Cite

A discrete adjoint approach for modeling unsteady aerodynamic design sensitivities

Conference 41st Aerospace Sciences Meeting and Exhibit · December 1, 2003 Presented is a discrete adjoint approach for computing steady and unsteady aerodynamic design sensitivities for compressible viscous flows about airfoil configurations. The nominal flow solver method is based on a harmonic balance solution technique, which ... Cite

A harmonic balance approach for modeling nonlinear aeroelastic behavior of wings in transonic viscous flow

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 Presented is a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling flutter onset and limit cycle oscillation (LCO) behavior of viscous transonic aeroelastic wing configurations. The AGARD 445.6 transonic wing conf ... Cite

Modeling limit cycle oscillations for an NLR 7301 airfoil aeroelastic configuration including correlation with experiment

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 Presented is an investigation into the modeling of limit cycle oscillation (LCO) behavior of an experimental transonic airfoil aeroelastic configuration using a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach. The aeroelas ... Cite

A harmonic balance approach for modeling nonlinear aeroelastic behavior of wings in transonic viscous flow

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · August 28, 2003 Presented is a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling flutter onset and limit cycle oscillation (LCO) behavior of viscous transonic aeroelastic wing configurations. The AGARD 445.6 transonic wing conf ... Cite

A discrete adjoint approach for modeling unsteady aerodynamic design sensitivities

Conference 41st Aerospace Sciences Meeting and Exhibit · January 1, 2003 Presented is a discrete adjoint approach for computing steady and unsteady aerodynamic design sensitivities for compressible viscous flows about airfoil configurations. The nominal flow solver method is based on a harmonic balance solution technique, which ... Full text Cite

A harmonic balance approach for modeling nonlinear aeroelastic behavior of wings in transonic viscous flow

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · January 1, 2003 Presented is a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling flutter onset and limit cycle oscillation (LCO) behavior of viscous transonic aeroelastic wing configurations. The AGARD 445.6 transonic wing conf ... Full text Cite

Blade excitation by aerodynamic instabilities - A compressor blade study

Conference American Society of Mechanical Engineers, International Gas Turbine Institute, Turbo Expo (Publication) IGTI · 2003 In this paper, we investigate non-synchronous vibrations (NSV) in turbomachinery, an aeromechanic phenomenon in which rotor blades are driven by a fluid dynamic instability. Unlike flutter, a self-excited vibration in which vibrating rotor blades and the r ... Cite

Parametric study of flutter for an airfoil in inviscid transonic flow

Journal Article Journal of Aircraft · 2003 A parametric study of flutter was conducted for an airfoil in inviscid transonic flow. An inviscid computational flow dynamic harmonic balance aerodynamic-Euler-based code was used for the investigation. The computational efficiency of the time-linearized ... Cite

Three-dimensional transonic aeroelasticity using proper orthogonal decomposition-based reduced-order models

Journal Article Journal of Aircraft · 2003 The proper orthogonal decomposition (POD-) based reduced-order modeling technique for modeling unsteady frequency-domain aerodynamics is developed for a large-scale computational model of an inviscid flow transonic wing configuration. When the methodology ... Cite

Modeling limit cycle oscillations for an NLR 7301 airfoil aeroelastic configuration including correlation with experiment

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2003 Presented is an investigation into the modeling of limit cycle oscillation (LCO) behavior of an experimental transonic airfoil aeroelastic configuration using a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach. The aeroelas ... Full text Cite

Computation of unsteady nonlinear flows in cascades using a harmonic balance technique

Journal Article AIAA Journal · 2002 A harmonic balance technique for modeling unsteady nonlinear flows in turbomachinery is presented. The analysis exploits the fact that many unsteady flows of interest in turbomachinery are periodic in time. Thus, the unsteady flow conservation variables ma ... Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter, and limit-cycle oscillations

Journal Article AIAA Journal · 2002 By the use of a state-of-the-art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergen ... Cite

A harmonic balance approach for modeling three-dimensional nonlinear unsteady aerodynamics and aeroelasticity

Conference ASME International Mechanical Engineering Congress and Exposition, Proceedings · January 1, 2002 Presented is a frequency domain harmonic balance (HB) technique for modeling nonlinear unsteady aerodynamics of three-dimensional transonic inviscid flows about wing configurations. The method can be used to model efficiently nonlinear unsteady aerodynamic ... Full text Cite

Modeling viscous transonic limit cycle oscillation behavior using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2002 Presented is a harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling limit cycle oscillation (LCO) behavior of aeroelastic airfoil configurations in a viscous transonic flow. For the NLM 7301 airfoil configuration studied, accountin ... Full text Cite

A parameter study of transonic airfoil flutter and limit cycle oscillation behavior

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2002 A parameter study of transonic airfoil flutter and limit cycle oscillation (LCO) behavior was presented. The effect of structural parameters and freestream Mach number of a transonic flow on the flutter and LCO was found out using inviscid computational fl ... Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Conference 19th AIAA Applied Aerodynamics Conference · December 1, 2001 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Cite

Three-Dimensional transonic Aeroelasticity using proper orthogonal decomposition based reduced order models

Conference 19th AIAA Applied Aerodynamics Conference · December 1, 2001 The proper orthogonal decomposition (POD) based reduced order modeling (ROM) technique for modeling unsteady frequency domain aerodynamics is developed for a large scale computational model of an inviscid flow transonic wing configuration. Using the method ... Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter and limit cycle oscillations

Conference 19th AIAA Applied Aerodynamics Conference · December 1, 2001 Using a state of the art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergence, flut ... Cite

A static/dynamic correction approach for reduced-order modeling of unsteady aerodynamics

Conference 39th Aerospace Sciences Meeting and Exhibit · December 1, 2001 Presented is a newly devised static/dynamic correction approach for eigenvector expansion based reduced-order modeling (ROM). When compared to the fundamental Ritz ROM formulation, along with the static and multiple static correction ROM approaches, the te ... Cite

Three-Dimensional transonic Aeroelasticity using proper orthogonal decomposition based reduced order models

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 The proper orthogonal decomposition (POD) based reduced order modeling (ROM) technique for modeling unsteady frequency domain aerodynamics is developed for a large scale computational model of an inviscid flow transonic wing configuration. Using the method ... Full text Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Full text Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter and limit cycle oscillations

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 Using a state of the art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergence, flut ... Full text Cite

A static/dynamic correction approach for reduced-order modeling of unsteady aerodynamics

Conference 39th Aerospace Sciences Meeting and Exhibit · January 1, 2001 Presented is a newly devised static/dynamic correction approach for eigenvector expansion based reduced-order modeling (ROM). When compared to the fundamental Ritz ROM formulation, along with the static and multiple static correction ROM approaches, the te ... Full text Cite

Three-dimensional transonic aeroelasticity using proper orthogonal decomposition based reduced order models

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2001 The proper orthogonal decomposition (POD) based reduced order modeling (ROM) technique for modeling unsteady frequency domain aerodynamics is developed for a large scale computational model of an inviscid flow transonic wing configuration. Using the method ... Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2001 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter and limit cycle oscillations

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2001 Using a state of the art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergence, flut ... Cite

Proper orthogonal decomposition technique for transonic unsteady aerodynamic flows

Journal Article AIAA Journal · 2000 A new method for constructing reduced-order models (ROM) of unsteady small-disturbance flows is presented. The reduced-order models are constructed using basis vectors determined from the proper orthogonal decomposition (POD) of an ensemble of small-distur ... Cite

Reduced-order modelling of unsteady small-disturbance flows using a frequency-domain proper orthogonal decomposition technique

Conference 37th Aerospace Sciences Meeting and Exhibit · January 1, 1999 © 1999 by Kenneth C. Hall, Jeffrey P. Thomas, and Earl H. Dowell.A new method for constructing reduced-order models (ROM) of unsteady small-disturbance flows is presented. The reduced-order models are constructed using basis vectors determined from the pro ... Cite

Reduced-order modelling of unsteady small-disturbance flows using a frequency-domain proper orthogonal decomposition technique

Conference 37th Aerospace Sciences Meeting and Exhibit · January 1, 1999 A new method for constructing reduced-order models (ROM) of unsteady small-disturbance flows is presented. The reduced-order models are constructed using basis vectors determined from the proper orthogonal decomposition (POD) of an ensemble of small-distur ... Full text Cite

Reduced order models in unsteady aerodynamics

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1999 A review is given on the status of reduced order modeling of unsteady aerodynamic systems. Starting with either a time domain or frequency domain computational fluid dynamics (CFD) analysis of unsteady aerodynamic flows, a large, sparse eigenvalue is solve ... Cite

Accurate schemes for advection and aeroacoustics

Conference 13th Computational Fluid Dynamics Conference · January 1, 1997 © 1997 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.Higher order upwind leapfrog schemes for two dimensional advection, acoustics and aeroacoustics are developed and applied to several examples. Advection schemes are ... Cite

Accurate schemes for advection and aeroacoustics

Conference 13th Computational Fluid Dynamics Conference · January 1, 1997 Higher order upwind leapfrog schemes for two dimensional advection, acoustics and aeroacoustics are developed and applied to several examples. Advection schemes are applied to scalar advection with uniform and nonuniform creeping flow speed. Acoustics sche ... Cite

Progress towards a new computational scheme for aeroacoustics

Conference 12th Computational Fluid Dynamics Conference · January 1, 1995 © 1995 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.To develop numerical schemes for aeroacoustics, numerical techniques based upon the upwind leapfrog method have been devised and tested on some model problems. Fourt ... Cite

Progress towards a new computational scheme for aeroacoustics

Conference 12th Computational Fluid Dynamics Conference · January 1, 1995 To develop numerical schemes for aeroacoustics, numerical techniques based upon the upwind leapfrog method have been devised and tested on some model problems. Fourth-order variations of the upwind leapfrog scheme are studied and methods for applying these ... Full text Cite

Development of non-dissipative numerical schemes for computational aeroacoustics

Conference 11th Computational Fluid Dynamics Conference, 1993 · January 1, 1993 The ability of popular computational fluid dynamic (CFD) methods to simulate the propagation of acoustic waves is assessed both theoretically and by numerical experiment. The schemes are used to model acoustic waves generated by a noise source situated at ... Full text Cite