@article {Rämmal:2008:0736-2501:107,
title = "Sound reflection at an open end of a circular duct exhausting hot gas",
journal = "Noise Control Engineering Journal",
parent_itemid = "infobike://ince/ncej",
publishercode ="ince",
year = "2008",
volume = "56",
number = "2",
publication date ="2008-03-01T00:00:00",
pages = "107-114",
itemtype = "ARTICLE",
issn = "0736-2501",
url = "https://www.ingentaconnect.com/content/ince/ncej/2008/00000056/00000002/art00002",
doi = "doi:10.3397/1.2898681",
keyword = "26.1.2, 72",
author = "R{\"a}mmal, Hans and Lavrentjev, J{\"u}ri",
abstract = "Sound reflection from hot flow duct openings is a classical problem in acoustics. In practice this is important for effective modelling and prediction of noise radiation from engine exhaust systems, burner pipelines, exhaust nozzles etc. Despite several experimental and theoretical
investigations in the field, there is still limited experimental data available to validate the existing theory. In the present study, experimental investigations of plane acoustic wave reflections at duct openings where a hot jet flows into relatively cold surrounding media have been carried
out. Heated air with well determined and homogenous chemical consistency along the duct axis was used as a testing media inside the duct during the experiments. The studied jet temperatures exhausting from the pipe ranged from room temperature up to 500\textdegreeC;.
The standard two-microphone technique was applied to determine the reflection properties at the duct opening. The experimental results for the reflection coefficient magnitude and phase have been compared with Munts theory and good correlation was found. This result is a first experimental
validation of the theory for hot flow conditions.",
}