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Unsteady aerodynamic model of a cargo container for slung-load simulation

Published online by Cambridge University Press:  03 February 2016

L. S. Cicolani ,
J. G. A. da Silva ,
E. P. N. Duque  and
M. B. Tischler
L. S. Cicolani
Affiliation:
Army/NASA Rotorcraft Division, Ames Research Center, Moffett Field California, USA
J. G. A. da Silva
Affiliation:
Army/NASA Rotorcraft Division, Ames Research Center, Moffett Field California, USA
E. P. N. Duque
Affiliation:
Deptartment of Mechanical Engineering, Northern Arizona University, Flagstaff, Arizona, USA
M. B. Tischler
Affiliation:
Army/NASA Rotorcraft Division, Aeroflightdynamics Directorate, (AMRDEC) US Army Research Development and Engineering Command, Moffett Field, California, USA
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Abstract

The problem of simulation models capable of predicting the aerodynamic instability of helicopter slung-load cargo containers and bluff bodies is addressed. Instability for these loads is known to depend on unsteady frequency-dependent aerodynamics, but simulation models that include the unsteady aerodynamics do not currently exist. This paper presents a method for generating such models using computational fluid dynamics (CFD) to generate forced-oscillation aerodynamic data and frequency domain system identification techniques to generate a frequency response from the CFD data and to identify a transfer function fit to the frequency response. The method is independent of the responsible flow phenomenon and is expected to apply to bluff-bodies generally. Preliminary results are presented for the case of the 6- by 6- by 8-ft CONEX (container express) cargo container. The present work is based on two-dimensional (2D) aerodynamic data for the CONEX side force and yaw moment generated by a forced oscillation in which frequency is varied smoothly over the range of interest. A first-order rational polynomial transfer function is found adequate to fit the aerodynamics, and this is shown to provide a good match with flight test data for the yawing motion of the CONEX.

Type
Research Article
Information
The Aeronautical Journal , Volume 108 , Issue 1085 , July 2004 , pp. 357 - 368
Copyright
Copyright © Royal Aeronautical Society 2004 

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