Abstract:

Gas flows through the passages that consist of various pores inside wood. The structure of the pores is complex and changeful, and the connections between the pores are different in the longitudinal, radial and tangential directions. The existing models for gas permeability of softwoods only considered the connection of the pores in one direction of wood grain or two directions. In this paper, a three-dimensional flow-resistor network was constructed according to the connection of the pores in longitudinal, radial and tangential directions. The flow-resistor network could be used to describe the mechanism of gas flow in the longitudinal direction. The equivalent flow-resistor of the flow-resistor network was work out by means of the real space renormalization approach, and the evaluation of the gas permeability of softwood could be evaluated from the equivalent flow-resistor. The calculated values of the longitudinal gas permeability of Masson pine(Pinus massoniana) was compaered with the corresponding measured values. There is a close agreement between the calculation and the measurement. It shows the validity of the theory on three-dimensional flow-resistor network.

Key words: Longitudinal gas permeability of wood, Flow-resistor, Flow resistor network, Real space renormalization