Numerical Wing/Store Interaction Analysis of a Parametric F16 Wing

A new numerical methodology to examine fluid-structure interaction of a wing/pylon/store system has been developed. The aeroelastic equation of motion of the complete system is solved iteratively in the time domain using a two-entity numerical code comprised of ABAQUS/Standard and the Unsteady-Vortex-Lattice Method. Both codes communicate through an iterative handshake procedure during which displacements and air loads are updated. For each increment in time the force/displacement equilibrium is found in this manner. The wing, pylon, and store data considered in this analysis are based on an F16 configuration that was identified to induce flutter in flight at subsonic speeds. The wing structure is modeled as an elastic plate and pylon and store are rigid bodies. The store body is connected to the pylon through an elastic joint exercising pitch and yaw degrees of freedom. Vortex-Lattice theory featuring closed ring-vortices and continuous vortex shedding to form the wakes is employed to model the aerodynamics of wing, store, and pylon. The methodology was validated against published data demonstrating excellent agreement with documented key phenomena of fluid-structure iteration. The model correctly predicts the effects of the pylon induced lateral flow disruption as well as wing-tip-vortex effects. It can identify the presence of aerodynamic interference between the store, pylon, and wing wakes and examine its significance with respect to the pressure and lift forces on the participating bodies. An elementary flutter study was undertaken to examine the dynamic characteristics of a stiff production pylon at near-critical airspeeds versus those of a soft-in-pitch pylon. The simulation reproduced the stabilizing effect of the stiffness reduction in the pitch motion. This idea is based on the concept of the decoupler pylon, introduced by Reed and Foughner in 1978 and flight tested in the early 1980's. Dedication To my wife, Melissa. iii Acknowledgments Upon graduating with a Master of Science from the Teschnische Universität Darmstadt in Germany, I came to Virginia Tech in December of 1993 to work on a three month research project under Dr. Daniel J. Inman. It was my first trip to the United States — back then I could not have possibly imagined the turn my life was about to take. Almost six years have gone by since then, during which I have experienced many of the profoundest moments of my life. Now, as this exciting chapter of my life is coming to closure and a new one is about to begin, I would …

[1]  G. Stein,et al.  Adaptive control of wing store flutter - A feasibility study , 1979 .

[2]  F. W. Cazier,et al.  Ground vibration test of F-16 airplane with initial decoupler pylon , 1984 .

[3]  J. T. Foughner,et al.  Passive control of wing/store flutter , 1980 .

[4]  Daniel J. Inman,et al.  ROBUST ADAPTIVE CONTROL OF STORE RELEASE EVENT FOR WINGS WITH EXTERNAL STORES , 1999 .

[5]  A. H. Nayfeh,et al.  Numerical simulations of dynamic/aerodynamic interactions , 1990 .

[6]  J. T. Foughner,et al.  Decoupler Pylon: A Simple, Effective Wing/Store Flutter Suppressor , 1980 .

[7]  Ali H. Nayfeh,et al.  A numerical method for general, unsteady aerodynamics , 1981 .

[8]  M. W. Kehoe,et al.  Ground vibration test of an F-16 airplane with modified decoupler pylons , 1986 .

[9]  Earl H. Dowell,et al.  Unsteady Aerodynamic Forces and Aeroelastic Response for External Store of an Aircraft , 1998 .

[10]  A. H. Nayfeh,et al.  A vortex-lattice method for general, unsteady aerodynamics , 1985 .

[11]  C. R. Kaykayoglu.  Unsteady Subsonic Aerodynamics for Maneuvering Wing/Fuselage/Pylon/Store Configuration and Store Separation Including Wake Effects. , 1993 .

[12]  I. G. Currie.  Fundamental mechanics of fluids , 1974 .

[13]  R. L. Haller,et al.  Online adaptive control of unstable aircraft wing flutter , 1990, 29th IEEE Conference on Decision and Control.

[14]  Dean T. Mook,et al.  A new method for actively suppressing flutter of suspension bridges , 1997 .

[15]  R. J. Zwaan,et al.  Calculation of Unsteady Subsonic Flow about Harmonically Oscillating Wing/Body Configurations , 1977 .

[16]  Marc Mignolet,et al.  On the nonlinear structural damping mechanism of the wing/store limit cycle oscillation , 1999 .

[17]  Thomas E. Noll,et al.  Investigation of internal control laws for wing/store flutter suppression , 1980 .

[18]  W. E. Triplett.  Wind tunnel correlation study of aerodynamic modeling for F/A-18 wing-store tip-missile flutter , 1984 .

[19]  J.W.G. Van Nunen,et al.  Investigation of the unsteady airloads on wing-store configurations in subsonic flow , 1977 .

[20]  Jennifer Heeg,et al.  An analytical and experimental investigation of flutter suppression via piezoelectric actuation , 1992 .

[21]  Daniel J. Inman,et al.  ℋ∞ controller design for wing/store flutter suppression , 1996 .

[22]  L. Erickson,et al.  Toward the routine aerodynamic analysis of complex configurations , 1990 .

[23]  Daniel J. Inman,et al.  Two-Dimensional Active Wing/Store Flutter Suppression Using H Theory , 1997 .

[24]  Sergio Preidikman,et al.  Numerical Simulations of Interactions Among Aerodynamics, Structural Dynamics, and Control Systems , 1998 .

[25]  Benjamin D. Hall,et al.  Numerical Simulations of the Aeroelastic Response of an Actively Controlled Flexible Wing , 1999 .

[26]  Zvi Rusak,et al.  Convergence characteristics of a vortex-lattice method for nonlinear configuration aerodynamics , 1985 .

[27]  N.A.V. Piercy,et al.  Aerodynamics for Engineers , 1979 .

[28]  Robert N. Desmarais,et al.  Wing/store flutter with nonlinear pylon stiffness , 1981 .

[29]  Earl H. Dowell,et al.  Studies in nonlinear aeroelasticity , 1988 .

[30]  Daniel J. Inman,et al.  Controller design for wings/store flutter suppression of an airfoil in incompressible flow , 1996 .

[31]  E. N. Tinoco,et al.  PAN AIR Applications to Weapons Carriage and Separation , 1981 .

[32]  A. Cenko.  PAN AIR Applications to Complex Configurations , 1983 .

[33]  Dean T. Mook,et al.  Numerical simulation of steady and unsteady, vorticity-dominated aerodynamic interference , 1994 .

[34]  William E. Triplett,et al.  Active Flutter Control-An Adaptable Applicationto Wing/Store Flutter , 1973 .

[35]  G. Stein,et al.  Self-tuning regulator design for adaptive control of aircraft wing/store flutter , 1982 .

[36]  C. Turner.  A study of the effect of store aerodynamics of wing/store flutter , 1981 .

[37]  H. Triebstein,et al.  Measurement of unsteady airloads on an oscillating engine and a wing/engine combination , 1994 .

[38]  R. M. Hicks,et al.  Euler and potential computational results for selected aerodynamic configurations , 1990 .

[39]  Yuan-Cheng Fung,et al.  An introduction to the theory of aeroelasticity , 1955 .

[40]  M. F. Unal,et al.  Aerodynamic characteristics of external store configurations at low speeds , 1995 .

[41]  W. Triplett,et al.  Active flutter control - An adaptable application to wing/store flutter , 1973 .

[42]  F. W. Cazier,et al.  Flight test of passive wing/store flutter suppression , 1986 .

[43]  Thomas E. Noll,et al.  Wing/Store Flutter Suppression Investigation , 1981 .

[44]  R. Roos.  Unsteady airloads on a harmonically pitching wing with external store , 1980 .

[45]  Earl H. Dowell,et al.  Nonlinear Aeroelasticity: An Overview , 1988 .

[46]  D. Almosnino.  High angle-of-attack calculations of the subsonic vortex flow on slender bodies , 1983 .

[47]  F. W. Cazier,et al.  Flight test of a decoupler pylon for wing/store flutter suppression , 1986 .

[48]  M. V. Dyke,et al.  An Album of Fluid Motion , 1982 .

[49]  Krishnamurty Karamcheti,et al.  Principles of ideal-fluid aerodynamics , 1966 .

[50]  W. Presz,et al.  Flow Separation over Axisymmetric Afterbody Models , 1974 .

[51]  Y.-R. Yang.  KBM METHOD OF ANALYZING LIMIT CYCLE FLUTTER OF A WING WITH AN EXTERNAL STORE AND COMPARISON WITH A WIND-TUNNEL TEST , 1995 .

[52]  L. Huttsell,et al.  Active Flutter Suppression on an F-4F Aircraft , 1980 .

[53]  G. J. Van Den Broek.  The Use of a Panel Method in the Prediction of External Store Separation , 1984 .

[54]  T. Holst.  Numerical solution of the full potential equation using a chimera grid approach , 1997 .

[55]  E. Wasserstrom,et al.  Numerical calculation of nonlinear aerodynamics of wing-body configurations , 1983 .

[56]  Ling-Cheng Zhao,et al.  Wing-store flutter analysis of an airfoil in incompressible flow , 1989 .

[57]  John A. Main,et al.  Piezoelectric Stack Actuators and Control System Design: Strategies and Pitfalls , 1997 .

[58]  Daniel J. Inman,et al.  Uncertainty models and associated trade-offs for wing/store flutter suppression , 1998, Other Conferences.

[60]  E. N. Tinoco,et al.  PAN AIR applications to weapons, carriage and separation , 1980 .

[61]  Zvi Rusak,et al.  Convergence characteristics of nonlinear vortex-lattice methods for configuration aerodynamics , 1983 .

[62]  D. Liu,et al.  Unsteady supersonic computations of arbitrary wing-body configurations including external stores , 1988 .

[63]  Dean T. Mook,et al.  SIMULATION OF THE INTERACTION BETWEEN AERODYNAMICS AND VEHICLE DYNAMICS IN GENERAL UNSTEADY GROUND EFFECT , 1989 .

[64]  Daniel J. Inman,et al.  Active Control of Store-Induced Flutter in Incompressible Flow , 1998 .

[65]  Ali H. Nayfeh,et al.  Application of the Vortex-Lattice Method to High-Angle-of-Attack Subsonic Aerodynamics , 1985 .

[66]  C. A. Harvey,et al.  Adaptive flutter suppression, analysis and test , 1983 .

[67]  L. Fornasier,et al.  HISSS - A higher-order subsonic/supersonic singularity method for calculating linearized potential flow , 1984 .