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Publikacje Pracowników Politechniki Lubelskiej

Publikacje Pracowników PL z lat 1990-2010

Publikacje pracowników Politechniki Lubelskie z lat 1990-2010 dostępne są jak dotychczas w starej bazie publikacji
LINK DO STAREJ BAZY

MNiSW
30
Lista A
Status:
Autorzy: Baruch Katarzyna , Majchrzak Aleksandra, Przysucha Bartosz, Szeląg Agata, Kamiński Tadeusz
Dyscypliny:
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Rok wydania: 2018
Wersja dokumentu: Drukowana | Elektroniczna
Język: angielski
Wolumen/Tom: 141
Strony: 250 - 260
Web of Science® Times Cited: 5
Scopus® Cytowania: 7
Bazy: Web of Science | Scopus
Efekt badań statutowych NIE
Materiał konferencyjny: NIE
Publikacja OA: NIE
Abstrakty: angielski
The absorption of scale model materials is generally measured in a scaled reverberation chamber, with frequency scaled according to the scale factor. Moreover, the acoustic absorption of the chamber needs to be reduced, especially the absorption of air. It depends not only on the volume of the chamber, but also on the air parameters: pressure, temperature and relative humidity. Most frequently, in order to reduce the air absorption, the air inside the model is dried or replaced with dry nitrogen, or a digital air absorption compensation is used. Air-drying methods are time consuming and require specialised equipment; digital compensation may in turn result in errors, hence the question arises whether scaling the air absorption is really necessary to achieve good accuracy of the sound absorption coefficient measurements. In order to answer this question, the authors firstly ran a theoretical analysis of the issue based on ISO 9613-1 formulas describing air acoustic absorption. Based on this analysis, the in fluence of particular air parameters on the total air absorption in the model reverberation chamber, A air(m2), was examined, together with the possibilities of scaling down the A air values. This ndicated, that the A air may be scaled by manipulating temperature or relative air humidity. For the needs of the study, the relative air humidity was chosen, as it was used by the predecessors and may be easily manipulated. In the next step, the experimental studies of sound absorption coefficient measurements were conducted in a 1:8 scale reverberation chamber for representative specimens at different relative air humidity values (3–45%). The gathered data was then statistically analysed. The results showed that the influence of relative air humidity on the accuracy of sound absorption coefficient measurements in model tests is negligible and therefore such measurements can be performed in the ambient air humidity of the test room. As a consequence, a conclusion was drawn that the A air value does not need to be scaled. Moreover, an attempt was made to identify the cause of the inaccuracy of the measurements – the analysis indicated that the values of the intensity attenuation coefficient m calculated according to ISO 9613-1, at model frequencies are not sufficiently accurate.