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기술보고서

기술보고서 게시판 내용
타이틀	Atmospheric Turbulence Modeling for Aero Vehicles: Fractional Order Fits
저자	Kopasakis, George
Keyword	ATMOSPHERIC TURBULENCE;; DYNAMIC RESPONSE;; DYNAMIC STRUCTURAL ANALYSIS;; ENGINE CONTROL;; FLIGHT CONTROL;; FREQUENCIES;; PROPULSION;; SIMULATION;; SPECTRA
URL	http://hdl.handle.net/2060/20110002734
보고서번호	NASA/TM-2010-216961
발행년도	2010
출처	NTRS (NASA Technical Report Server)
ABSTRACT	Atmospheric turbulence models are necessary for the design of both inlet/engine and flight controls, as well as for studying coupling between the propulsion and the vehicle structural dynamics for supersonic vehicles. Models based on the Kolmogorov spectrum have been previously utilized to model atmospheric turbulence. In this paper, a more accurate model is developed in its representative fractional order form, typical of atmospheric disturbances. This is accomplished by first scaling the Kolmogorov spectral to convert them into finite energy von Karman forms and then by deriving an explicit fractional circuit-filter type analog for this model. This circuit model is utilized to develop a generalized formulation in frequency domain to approximate the fractional order with the products of first order transfer functions, which enables accurate time domain simulations. The objective of this work is as follows. Given the parameters describing the conditions of atmospheric disturbances, and utilizing the derived formulations, directly compute the transfer function poles and zeros describing these disturbances for acoustic velocity, temperature, pressure, and density. Time domain simulations of representative atmospheric turbulence can then be developed by utilizing these computed transfer functions together with the disturbance frequencies of interest.