CFD Calculation of Aerodynamic Indicial Functions for a Generic Fighter Configuration

A reduced-order modeling of nonlinear and unsteady aerodynamics based on indicial (step) response functions and Duhamel’s superposition integral is presented. These time-domain models could predict the unsteady aerodynamic responses of an aircraft performing any arbitrary motion over a wide range flight regime, but require calculating a large number of response functions. A method to efficiently reduce the number of indicial response calculations is tested. This method uses a time-dependent surrogate model (input/output mapping) to fit the relationship between flight conditions and response functions from a limited number of response simulations (samples). Each sample itself is directly calculated from unsteady computational fluid-dynamic simulations and a grid-motion tool. An important feature of this approach is uncoupling the effects of angle of attack and pitch rate from pitching motions. The aerodynamic models are then created with predicted indicial functions at each time instant using the surrogate model. This model is then applied for aerodynamics modeling of a generic fighter configuration performing arbitrary pitching and plunging motions at various Mach numbers. Results presented show that reduced-order models can accurately predict time-marching solutions of aircraft for a wide range of motions, but with the advantage that reduced-order model predictions require on the order of a few seconds once the model is created. The results also demonstrate that the surrogate model being tested aids in reducing the overall computational efforts to develop reduced-order models.

[1]  R. Cummings,et al.  Detached-eddy simulation with compressibility corrections applied to a supersonic axisymmetric base flow , 2002 .

[2]  Russell M. Cummings,et al.  Challenges in the aerodynamics modeling of an oscillating and translating airfoil at large incidence angles , 2012 .

[3]  Mehdi Ghoreyshi,et al.  Accelerating the Numerical Generation of Aerodynamic Models for Flight Simulation , 2009 .

[4]  Russell M. Cummings,et al.  Aerodynamic Analysis of a Generic Fighter Using Delayed Detached-Eddy Simulation , 2009 .

[5]  J. Forsythe,et al.  Unsteady Computations of Abrupt Wing Stall Using Detached-Eddy Simulation , 2005 .

[6]  J. R. Chambers,et al.  Overview of the abrupt wing stall program , 2004 .

[7]  T Niranjana,et al.  Wind tunnel dynamic flying study of the pitching moment derivatives of the Standard Dynamics Model in active control , 1987 .

[8]  James R. Forsythe,et al.  Detached-eddy simulation of fighter aircraft at high alpha , 2002 .

[9]  A. Da Ronch,et al.  Evaluation of Dynamic Derivatives Using Computational Fluid Dynamics , 2012 .

[10]  M. E. Beyers,et al.  Subsonic roll oscillation experiments on the Standard Dynamics Model , 1983 .

[11]  Heinz Fuchs,et al.  Prediction of Dynamic Derivatives , 1988 .

[12]  Jonathan E. Cooper,et al.  Introduction to Aircraft Aeroelasticity and Loads , 2007 .

[13]  L. B. Schiff,et al.  Aerodynamic characteristics of the standard dynamics model in coning motion at Mach 0.6 , 1985 .

[14]  Russell M. Cummings,et al.  CFD Modeling for Trajectory Predictions of a Generic Fighter Configuration , 2011 .

[15]  Clinton P. T. Groth,et al.  Assessment of Riemann solvers for unsteady one-dimensional inviscid flows for perfect gases , 1988 .

[16]  J. R. Chambers,et al.  Accomplishments of the Abrupt-Wing-Stall Program , 2005 .

[17]  Herbert Wagner.  Über die Entstehung des dynamischen Auftriebes von Tragflügeln , 1925 .

[18]  X. Z. Huang,et al.  Wing and FIN Buffet on the Standard Dynamics Model , 2000 .

[19]  Robert M. Hall,et al.  Historical Review of Uncommanded Lateral-Directional Motions at Transonic Conditions , 2004 .

[20]  Russell M. Cummings,et al.  Experiences in accurately predicting time-dependent flows , 2008 .

[21]  Russell M. Cummings,et al.  Computational Investigation into the Use of Response Functions for Aerodynamic-Load Modeling , 2012 .