木材15樹種の繊維直角方向空気透過性

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The transverse flow rate of air througth flat- or quarter-sawn boards of fifteen species including domestic and imported woods was measured. The test specimens were disk type and the thickness (d) was 5-20 mm, though extreme thin specimens had been used in the past works. The pressure difference between the two faces of the specimen was in the range of 10-70 cmHg. The permeability characteristics for each species and the effect of d on the permeability under both unsteady and steady states were discussed. The results obtain ed were as follows. (1) The transverse air flow through the specimen took place with a time lag for the start of reducing pressure. The flow rate increased gradually and, after a short or long increaing course, reached a constant value in the steady state. The time required to reach the steady state from the start and the flow rate at the state depended on the wood species and d. (2) The transverse permeability value calculated on the basis of Darcy's law in the steady state (k_g) was extremely different from one species to another. In coniferous trees, the range of k_g at 5mm of d was (0.3-15.2)×10^<-5>, and in broad leaved trees that of k_g was (0.02-32.0)×10^<-5>. (3) In the cases of six species among all species tested, k_g showed nealy a constant value regardless of d. But in the cases of the other species, a linear relationship was found between d and logarithm of k_g as expressed by k_g=k_0exp (b・d), and the sign of b was positive for seven species and negative for two species. (4) The longitudinal/ transverse permeability ratio for the specimens of 20mm along the flow direction was within the range of (1.5-50.2)×10^3 in coniferous trees and changed over a wide range of 2.1×10^3-6.7×10^7 in broad leaved trees.
社団法人日本材料学会の論文
1985-08-15

木材15樹種の繊維直角方向空気透過性

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