Experimental Analysis on the Exact' Cremer Impedance in Rectangular Ducts KTH Royal Institute of Technology

Format:

Conference/Event

Author/Creator:

Zhang, Zhang, author.

Contributor:

Abom, Mats

Peerlings, Luck

Tiikoja, Heiki

Conference Name:

10th International Styrian Noise, Vibration & Harshness Congress: The European Automotive Noise Conference (2018-06-20 : Graz, Austria)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2018

Summary:

Cremer impedance, first proposed by Cremer (Acustica 3, 1953) and then improved by Tester (JSV 28, 1973), refers to the locally reacting boundary condition that can maximize the attenuation of a certain acoustic mode in a uniform waveguide. One limitation in Tester's work is that it simplified the analysis on the effect of flow by only considering high frequencies or the well cut-on' modes. This approximation is reasonable for large duct applications, e.g., aero-engines, but not for many other cases of interest, with the vehicle intake and exhaust system included. A recent modification done by Kabral and others (Acta Acustica united with Acustica 102, 2016) has removed this limitation and investigated the exact' solution of Cremer impedance for circular waveguides, which reveals an appreciable difference between the exact and classic solution in the low frequency range. Consequently, the exact solution can lead to a much higher low-frequency attenuation level. In addition, the exact solution is found to exhibit some special properties at very low frequencies, e.g., a negative resistance. In this paper, liners designed on the basis of the exact solution are tested and the difference between the exact and classic solution in the low frequency range (not low enough to go into the negative resistance region) is experimentally investigated

Notes:

Vendor supplied data

Publisher Number:

2018-01-1523

Access Restriction:

Restricted for use by site license