关键词: 木材, 流体, 流量率, 渗透性

Abstract: This paper dealt with the longitudinal air permeability of 40 important Chinese woods. Their perweable characteristics and laws were revealed. The air permeabilities measured at about 10% M. C for softwoods were between 0. 00957 and 1. 87173 darcy,while for hardwoods were 0. 00195 to 13. 49867 darcy. The permeability of sapwood of both softwoods and hardwoods was much higher than that of heartwood. The permeability of wood was not related to its density in regardless of softwood or hardwoodand the same or different species. In the 40 species studied, the permeability of heartwood of all softwoods, about 70% ring-porous and about 30% diffuse porous or hemidiffuse porous woods was below 0.1 darcy, which belonged to a low range of permeability. The species of low permeability in softwoods were more than that in hardwoods because the numbers of cell cross per unit length in axial direction which hinder flow of fluid in the former were more than that in the latter. The species of low permeability in ring-porous woods were more than that in diffuse porous or hemidiffuse porous woods as a result of the existance of tylosis or gum which obstructed vessels and pit membrane openings between vessels. As far as softwood was concerned, the difference of permeability relied on the effective radius and number of pit membrane openings, as for ring-porous woods was also dependent on the existance and number of tylosis or gum in the vessels, even the number and size of openings in the tylosis in addition to the pit membrane openings between vessels, and as for diffuse or hemidiffuse porous woods resulted from the radius and number of pit membrane openings between vessels, the type of perforation plate contained in the vessels and the radius and number of vessels.

Key words: Wood, Fluid, Flow rate, Permeability