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Advances in Aircraft and Spacecraft Science
  Volume 4, Number 2, March 2017, pages 203-218
DOI: http://dx.doi.org/10.12989/aas.2017.4.2.203
 
open access

Multiple input describing function analysis of non-classical aileron buzz
Muhammad I. Zafar, Francesca Fusi and Giuseppe Quaranta

 
Abstract
    This paper focuses on the computational study of nonlinear effects of unsteady aerodynamics for non-classical aileron buzz. It aims at a comprehensive investigation of the aileron buzz phenomenon under varying flow parameters using the describing function technique with multiple inputs. The limit cycle oscillatory behavior of an asymmetrical airfoil is studied initially using a CFD-based numerical model and direct time marching. Sharp increases in limit cycle amplitude for varying Mach numbers and angles of attack are investigated. An aerodynamic describing function is developed in order to estimate the variation of limit cycle amplitude and frequency with Mach number and angle of attack directly, without time marching. The describing function results are compared to the amplitudes and frequencies predicted by the CFD calculations for validation purposes. Furthermore, a limited sensitivity analysis is presented to demonstrate the potential of the approach for aeroelastic design.
 
Key Words
    computational aeroelasticity; describing function; aileron buzz; fluid structure interaction; limit cycle oscillation
 
Address
Muhammad I. Zafar, Francesca Fusi and Giuseppe Quaranta : Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano, Campus Bovisa Sud, via La Masa, 34, 20165 – Milano, Italy
 

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