Steady-state flow resistance measuring cylinder for porous sound absorption material

Abstract

The invention discloses a steady-state flow resistance measuring cylinder for a porous sound absorption material. The steady-state flow resistance measuring cylinder comprises a top cover, an outer sleeve, a measuring seat and a supporting cylinder or a rubber sealing ring connected between the outer sleeve and the measuring seat, the bottom face of a cover plate is connected with a section of inner cylinder to form the top cover, and an inner cylinder airflow slit is formed in the side wall of the inner cylinder; the outer sleeve is provided with a cylindrical inner cavity with an upper half cylinder and a lower half cylinder, and an outer sleeve airflow slit is formed in the side wall of the upper half cylinder; the top cover and the inner sleeve are matched to form an airflow expansion cavity, and airflow introduced from an airflow slit of the outer sleeve passes through the airflow expansion cavity and then enters an inner cavity of the upper half sleeve. the inner cavity of the measuring seat is communicated with the supporting cylinder; and the supporting cylinder and the rubber sealing ring can be replaced so as to realize flow resistance measurement of a volumetric porous material test piece and flow resistance measurement of a sheet type material test piece respectively, and the flow resistance measuring device has the capacities of lossy measurement and nondestructive measurement, can effectively reduce the influence of the external environment on flow resistance measurement, and improves the measurement precision.

Description

technical field [0001] The invention relates to the technical field of flow resistance measurement, in particular to a steady-state flow resistance measurement cylinder of a porous sound-absorbing material. Background technique [0002] Acoustic porous materials are widely used in the field of sound absorption and noise reduction, and their sound absorption performance is closely related to the flow resistance, which is one of the Biot parameters of materials. At present, the direct measurement of the flow resistance of acoustic materials has been standardized by ISO_9053, which is obtained by measuring the pressure difference and air volume flow generated by the steady-state airflow through the porous material. Flow resistance measurement is mainly divided into DC measurement and AC measurement. The direct current measurement and the alternating current measurement can be classified according to the type of air flow, the publication number is CN106918442 "a kind of porous ...

AI Technical Summary

Problems solved by technology

[0003] Lossy measurement is widely used in volumetric porous materials, that is, the acoustic wavelength is smaller than the thickness of the material. However, for acoustic materials, there is a large difference between the lossy measurement and the original flow resistance value of the material under actual application conditions.

Such differences directly lead to lossy measurements that cannot correctly guide sound absorption and noise reduction

At the same time, for thinner and softer sheet-type sound-absorbing materials, that is, the wavelength of the sound wave is greater than the thickness of the material, such as car roofs, fabrics, curtains, etc., when performing lossy measurements, the material needs to be adhered to a rigid support. One situation changes the boundary conditions and increases the measurement error

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