NASA Logo

NTRS - NASA Technical Reports Server

Back to Results
Finite Difference Time Marching in the Frequency Domain: A Parabolic Formulation for Aircraft Acoustic Nacelle DesignAn explicit finite difference iteration scheme is developed to study harmonic sound propagation in aircraft engine nacelles. To reduce storage requirements for large 3D problems, the time dependent potential form of the acoustic wave equation is used. To insure that the finite difference scheme is both explicit and stable, time is introduced into the Fourier transformed (steady-state) acoustic potential field as a parameter. Under a suitable transformation, the time dependent governing equation in frequency space is simplified to yield a parabolic partial differential equation, which is then marched through time to attain the steady-state solution. The input to the system is the amplitude of an incident harmonic sound source entering a quiescent duct at the input boundary, with standard impedance boundary conditions on the duct walls and duct exit. The introduction of the time parameter eliminates the large matrix storage requirements normally associated with frequency domain solutions, and time marching attains the steady-state quickly enough to make the method favorable when compared to frequency domain methods. For validation, this transient-frequency domain method is applied to sound propagation in a 2D hard wall duct with plug flow.
Document ID
19970001340
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Baumeister, Kenneth J. (NASA Lewis Research Center Cleveland, OH United States)
Kreider, Kevin L. (Akron Univ. Akron, OH United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1996
Subject Category
Acoustics
Report/Patent Number
NAS 1.15:106839
NASA-TM-106839
E-9403
Report Number: NAS 1.15:106839
Report Number: NASA-TM-106839
Report Number: E-9403
Meeting Information
Meeting: International Mechanical Engineering Congress and Exposition
Location: San Francisco, CA
Country: United States
Start Date: November 12, 1995
End Date: November 17, 1995
Sponsors: American Society of Mechanical Engineers
Accession Number
97N11159
Funding Number(s)
PROJECT: RTOP 505-62-52
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Related Records

There are no records associated with this record.
No Preview Available