ESDU 00024
The acoustic attenuation of absorbent linings in rectangular flow ducts with application to annular flow ducts.
Abstract:
ESDU 00024 introduces a computerised method for estimating the sound power attenuation of absorbent linings in constant section straight rectangular ducts with axial flow. The method is based on a theoretical model that takes the velocity profile across the duct, assumed constant axially, into consideration. The method can also be applied to annular ducts with inner radius to outer radius ratios as low as 0.5, below which the risk of error increases. Up to ten duct sections with different linings in each can be considered. The program, ESDUpac A0024, permits the user to output results at thirdoctave band centre frequencies, at specified frequencies, or over a frequency range with constant step increment between the frequencies. Equal energy in each mode or equal amplitude in each mode can be selected. Individual modes can be weighted. The output can be total attenuation at each frequency, or the total attenuation and the attenuation in each mode at each frequency. The format of the input file is explained and a second ESDUpac, B0024, facilitates its construction. The input requires values for the normalised acoustic impedance for each lined section and, for low Mach numbers, values may be taken from ESDU 74003 and 74004, while for higher Mach numbers, the manufacturer's values will need to be used. Worked examples illustrate the various features of the program.Indexed under:
 Acoustic Impedance
 Aircraft Noise
 Boundary Layer
 Noise
 Noise/sound Propagation
 Sound
 Velocity Profile
Details:
Data Item ESDU 00024  

Format: 

Status: 

Previous Releases: 

ISBN: 

The Data Item document you have requested is available only to subscribers or purchasers.
 Subscribers login here.
 If you are not an ESDU subscriber you can
 find out how to subscribe, or
 purchase this Data Item from the IHS Standards Store.
This Data Item is complemented by the following software:
Name  Details  

ESDUpac A0024 
This program is only available to subscribers. 

ESDUpac B0024 
This program is only available to subscribers. 
Explore ESDU
ESDU Series:
 Aerodynamics
 Aircraft Noise
 Composites
 Dynamics
 Fatigue  Endurance Data
 Fatigue  Fracture Mechanics
 Fluid Mechanics, Internal Flow
 Fluid Mechanics, Internal Flow (Aerospace)
 Heat Transfer
 Mechanisms
 Performance
 Physical Data, Chemical Engineering
 Stress and Strength
 Structures
 Transonic Aerodynamics
 Tribology
 Vibration and Acoustic Fatigue
 Wind Engineering
ESDU Packages:
See this document in context
ESDU Series
 Home  AZ index  Contact Us  Help  About Us  Terms of Use  Privacy Policy  How we use cookies  How to Subscribe 
© 19992019 IHS ESDU, part of IHS Inc.