title: Airflow resistance measurement for a layer of granular material based on the Helmholtz resonance phenomenon.
abstract: A Helmholtz resonance technique was employed to predict the airflow resistance of layers of granular materials, namely glass beads, brown rice, soybean, adzuki beans, and corn kernels. Each granular sample was placed on the tube mouth of an open-type Helmholtz resonator. The resonant frequency was determined by measuring the electric impedance of a loudspeaker that was installed in the resonator and driven by a chirp signal linearly sweeping from 90 to 220 Hz for 6.0 s. For a changing sample layer thickness, the resonant frequency was measured, and the specific airflow resistance was calculated by measuring the static pressure drop required for N2gas to flow through the layer at a constant velocity of 0.042 m/s. When the thickness of the layer was fixed, the Helmholtz resonant frequency decreased as the specific airflow resistance increased, regardless of the kind of granular material.
authors.affiliation: a Faculty of Applied Biological Sciences, Department of Applied Life Science , Gifu University , Gifu , Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Nishizu
authors.affiliation: b Sanchi-Keiei-Support (Registered SME Management Consultant Office) , Toyonaka, Osaka , Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Tomatsu
authors.affiliation: a Faculty of Applied Biological Sciences, Department of Applied Life Science , Gifu University , Gifu , Japan.
authors.forename: Nakako
authors.initials: N
authors.lastname: Katsuno
mesh_terms: D005504:Food Analysis; D012275:Oryza / Q000737:chemistry; D011312:Pressure; D013025:Glycine max / Q000737:chemistry; D000070658:Vigna / Q000737:chemistry; D003313:Zea mays / Q000737:chemistry
keywords: Helmholtz resonance; dissipation of acoustic energy; layer of granular material; specific airflow resistance