Using simulation to determine elbow and side branch attenuation and duct breakout transmission loss

K. Ruan, D. W. Herrin

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

7 Scopus citations


The primary path of noise propagation in buildings is airborne transmission from building equipment through ducts. Attenuation is increased if elbows or side branches are introduced into a duct. In a companion paper (Ruan and Herrin 2016), finite element analysis was used to predict the insertion losses of straight lined and unlined ducts and results were validated with measurement. In this work, finite element analysis is used to predict the attenuation of elbows and side branches. Results for elbows and branches are compared to ASHRAE Handbook - H VAC Applications values withgoodagreement. An important secondary noise transmission path is through duct walls into rooms. This path, which is often termed breakout noise, is also investigated using the finite element approach, and results are correlated with an analytical solution and the ASHRAE Handbook with good agreement. Of note, it is demonstrated that the breakout transmission loss is much less than the insertion loss through lined rectangular ducts at some frequencies. This suggests that breakout noise is the dominant noise path at these frequencies.

Original languageEnglish
Title of host publicationASHRAE Transactions
Number of pages10
ISBN (Electronic)9781939200259
StatePublished - 2016
Event2016 ASHRAE Winter Conference - Orlando, United States
Duration: Jan 23 2016Jan 27 2016

Publication series

NameASHRAE Transactions
ISSN (Print)0001-2505


Conference2016 ASHRAE Winter Conference
Country/TerritoryUnited States

Bibliographical note

Publisher Copyright:
© 2016 ASHRAE.

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering


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