국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Broadband Noise Prediction When Turbulence Simulation Is Available - Derivation of Formulation 2B and Its Statistical Analysis
저자	Farassat, Fereidoun;; Casper, Jay H.
Keyword	AEROACOUSTICS;; AERODYNAMIC NOISE;; BROADBAND;; FAR FIELDS;; FFOWCS WILLIAMS-HAWKINGS EQUATION;; NEAR FIELDS;; NUMERICAL ANALYSIS;; ROTOR BLADES;; ROTOR DYNAMICS;; SEMIEMPIRICAL EQUATIONS;; SIMULATION;; STATISTICAL ANALYSIS;; TURBULENCE
URL	http://hdl.handle.net/2060/20120008645
보고서번호	NF1676L-12184
발행년도	2012
출처	NTRS (NASA Technical Report Server)
ABSTRACT	We show that a simple modification of Formulation 1 of Farassat results in a new analytic expression that is highly suitable for broadband noise prediction when extensive turbulence simulation is available. This result satisfies all the stringent requirements, such as permitting the use of the exact geometry and kinematics of the moving body, that we have set as our goal in the derivation of useful acoustic formulas for the prediction of rotating blade and airframe noise. We also derive a simple analytic expression for the autocorrelation of the acoustic pressure that is valid in the near and far fields. Our analysis is based on the time integral of the acoustic pressure that can easily be obtained at any resolution for any observer time interval and digitally analyzed for broadband noise prediction. We have named this result as Formulation 2B of Farassat. One significant consequence of Formulation 2B is the derivation of the acoustic velocity potential for the thickness and loading terms of the Ffowcs Williams-Hawkings (FW-H) equation. This will greatly enhance the usefulness of the Fast Scattering Code (FSC) by providing a high fidelity boundary condition input for scattering predictions.