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MULTIPLE ORDER POLE PURE LAG RATIONAL-FUNCTION APPROXIMATIONS FOR UNSTEADY AERODYNAMICS

DSpace at IIT Bombay

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Title MULTIPLE ORDER POLE PURE LAG RATIONAL-FUNCTION APPROXIMATIONS FOR UNSTEADY AERODYNAMICS
 
Creator MUJUMDAR, PM
BALAN, N
 
Description Most existing rational function approximations for the time domain representation of unsteady generalized airloads lead to an ill-conditioned system dynamic matrix in the presence of closely spaced poles. A new class of multiple order pole pure lag rational function approximations (RFA) is presented in this article to overcome this problem. The present class of approximations is developed as a consistent generalization of an existing simple pole pure lag RFA while preserving the resulting state vector dimension. A nonlinear nongradient optimization technique is used for the computation of the lag poles in the approximation. The structure of the proposed class of approximations preserves the pure lag form, thus allowing for specific physical interpretations of the individual terms in the approximation and renders the subsequent optimization problem simpler, in that fewer constraints need to be imposed during the optimization process. Furthermore, the new class of approximations leads to substantial reduction in computational costs for optimization for a given fit accuracy, in comparison to existing simple pole approximations. Results are presented for the case of a typical delta wing fighter aircraft configuration.
 
Publisher AMER INST AERONAUT ASTRONAUT
 
Date 2011-07-15T10:00:49Z
2011-12-26T12:49:24Z
2011-12-27T05:45:20Z
2011-07-15T10:00:49Z
2011-12-26T12:49:24Z
2011-12-27T05:45:20Z
1995
 
Type Article
 
Identifier JOURNAL OF AIRCRAFT, 32(2), 334-342
0021-8669
http://dx.doi.org/10.2514/3.46720
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4232
http://hdl.handle.net/10054/4232
 
Language en