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.
|Title of host publication||ASHRAE Transactions|
|Number of pages||10|
|State||Published - 2016|
|Event||2016 ASHRAE Winter Conference - Orlando, United States|
Duration: Jan 23 2016 → Jan 27 2016
|Conference||2016 ASHRAE Winter Conference|
|Period||1/23/16 → 1/27/16|
Bibliographical notePublisher Copyright:
© 2016 ASHRAE.
ASJC Scopus subject areas
- Building and Construction
- Mechanical Engineering