- Additional Authors
- Description
- iii, 99 p. : ill.
- Summary
- "A description of the structure of the Annular Flow Duct Program (AFDP) for the calculation of acoustic suppression due to treatment in a finite length annular duct carrying sheared flow is presented. Although most appropriate for engine exhaust ducts, this program can be used to study sound propagation in any duct that maintains annular geometry over a considerable length of the duct. The program is based on the modal analysis of sound propagation in ducts with axial segments of different wall impedances. For specified duct geometry, wall impedance, flow and acoustic conditions in the duct (including mode amplitude distribution of the source) and duct termination reflection characteristics, the program calculates the suppression due to the treatment in the duct. The presence of forward and backward traveling modes in the duct due to the reflection and redistribution of modes at segment interfaces and duct end terminations are taken into account in the calculations. The effects of thin wall boundary layers (with a linear or mean flow velocity profile) on the acoustic propagation are also included in the program. A functional description of the major subroutines is included and a sample run is provided with an explanation of the output."--NTIS abstract.
- Series Statement
- CR ; 175067
- Uniform Title
- NASA contractor report ; NASA CR-175067.
- Subject
- Note
- "May 1983."
- Distributed to depository libraries in microfiche.
- Type of Report (note)
- Reproduction (note)
- Funding (note)
- NASA (NASA Lewis Research Center) contract no.
- Call Number
- GPO Microfiche NAS 1.26:175067/2
- OCLC
- marcive233990580
- Author
Joshi, M. C.
- Title
Turbofan aft duct suppressor study [microform] : program listing and user's guide / M.C. Joshi, R.E. Kraft.
- Imprint
Long Beach, CA : Douglas Aircraft Company ; [Cleveland, Ohio] : National Aeronautics and Space Administration, Lewis Research Center, [1983]
- Series
CR ; 175067
NASA contractor report ; NASA CR-175067.
- Type Of Report
Final report.
- Reproduction
Microfiche. [Washington, D.C.] : National Aeronautics and Space Administration, 1986. 2 microfiches : negative.
- Funding
NASA (NASA Lewis Research Center) contract no. NAS3-22766
- Indexed Term
Acoustic propagation - Annular ducts - Engine noise - Exhaust systems - Noise reduction - Turbofan engines - Applications programs (Computers) - User manuals (Computer programs) - Acoustic impedance - Duct geometry - Propagation modes - Wave reflection
- Added Author
Kraft, R. E. (Robert Eugene)
Douglas Aircraft Company.
Lewis Research Center.
United States. National Aeronautics and Space Administration.
- Other Form:
Print version: Joshi, M. C. Turbofan aft duct suppressor study. (OCoLC)806325395
- Gpo Item No.
0830-H-14 (MF)
- Sudoc No.
NAS 1.26:175067/2