Measured anisotropic air flow resistivity and sound attenuation of glass wool

Abstract

The air flow resistivity of glass wool has been measured in different directions. The glass wool was delivered from the manufacturer as slabs measuring 100ϫ600ϫ900 mm 3 , where the surface 600ϫ900 mm 2 was parallel with the conveyor belt used in the manufacturing. Directions in the glass wool are described by a coordinate system with the X axis perpendicular to the conveyor belt, the Z axis in the direction the conveyor belt moves, and the Y axis perpendicular to the two other axes. It was found that the resistivities in the Y and Z directions were equal in all cases. For density 14 kg/m 3 the mean resistivity in the X direction was 5.88 kPa s m Ϫ2 and in the Y direction 2.94 kPa s m Ϫ2. For density 30 kg/m 3 the mean resistivity in the X direction was 15.5 kPa s m Ϫ2 and in the Y direction 7.75 kPa s m Ϫ2. A formula for prediction of resistivity for other densities is given. By comparing measured values of sound attenuation with results calculated from resistivity data, it is demonstrated that the measured attenuation can be predicted in a simple manner.

Light Electrospun Polyvinylpyrrolidone Blanket for Low Frequencies Sound Absorption

“…It is worth remembering that the polymer molecular weight is one of the most important parameters [11−14, 16, 22] . In particular: (1) the greater the molecular weight, the lower the polymer concentration that assures the occurrence of sufficient chain entanglements and, therefore, the avoidance of bead formation [22] ; (2) the fiber size increases [13,14,16,22] with increasing molecular weight and polymer concentration in the electrospun solution.…”

Identification of the full anisotropic flow resistivity tensor for multiple glass wool and melamine foam samples

“…5 10 200 Sample 2 Y: 10.9 9 100 9 300 10. 5 8 700 Sample 1 Z: 9.6 10 000 9 800 9.6 9 800 9.2 9 900 9.2 9 900 sample 3 but is still interesting to investigate for the purpose of comparison. The in-plane values are calculated here as the average of the six values measured in x and y directions (see Table VIII).…”

“…5 This could be attributed to the low bulk stiffness of glass wool in the stacking direction, which may be up till 50 times lower than the bulk stiffness in the in-plane direction, 5 and thus easily deformable in this direction. The difference between the in-plane and out-of-plane bulk stiffness has an influence on the sample preparation and mounting conditions, which may account for the relatively large difference (23%) between measured and FE computed flow resistivity in Table VIII.…”

Effects of different parameters on acoustic properties of activated carbon fiber felts

“…Inorganic fibers have great superiority over natural fibers in resisting fire and corrosion and have great competitive edge in prices, but are limited in practical use due to their threat to the environment and human well-being. In the field of inorganic fibers, glass fibers (Kino & Ueno, 2008a;Tarnow, 1999Tarnow, , 2000Tarnow, , 2002Wang & Tong, 2001) are the most typical inorganic sound absorption materials. The occurrence of synthetic fibers expands the field of research as they are exceptional in sound absorption, corrosion-resistance, and are recyclable, of which polypropylene fibers (Alonso et al, 1992;Chen & Jiang, 2007) and polyester fibers (Garai & Pompoli, 2005;Kino & Ueno, 2008b;Tascan & Vaughn, 2008) are the most typical.…”