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Sound-tube measurements of the relaxation frequency of moist nitrogenAt audible frequencies, the vibrational relaxation of nitrogen contributes significantly to the absorption of sound in still air. The accurate measurement of the humidity dependence of the relaxation frequency of nitrogen, as yet, has eluded careful measurement due to the difficulty in measuring small absorption at low frequencies. Recently, equipment has been constructed for measuring sound absorption in air as a function of humidity over the frequency range from 4 to 100 kHz. In the experiment described here, the temperature and humidity range of this equipment has been extended so that it can be used to study the relaxation absorption in nitrogen at temperatures from 311 K to 418 K. The results indicate that, over this temperature range, the frequency of maximum absorption in moist nitrogen, f, can be given by f/P = 260 x h, Hz/atm, where h is the percent mole fraction of water, and P is the pressure in atm. To the accuracy of the measurements reported here, f is independent of temperature over the range of temperatures at which the measurements were made.
Document ID
19770065144
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Chang, D.
(Mississippi Univ. University, MS, United States)
Shields, F. D.
(Mississippi Univ. University, MS, United States)
Bass, H. E.
(Mississippi, University University, Miss., United States)
Date Acquired
August 9, 2013
Publication Date
September 1, 1977
Publication Information
Publication: Acoustical Society of America
Subject Category
Acoustics
Accession Number
77A47996
Funding Number(s)
CONTRACT_GRANT: NSG-1317
Distribution Limits
Public
Copyright
Other

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