Abstract: In view of the existing problems of ISO6358 standard as well as its expanded expression in representing the flow rate characteristics of porous media, a Darcy-Forchheimer model is established to describe the flow rate characteristics considering the flow pattern in porous media. Darcy regime provides a good approximate relation between the flow velocity and pressure gradient at sufficiently small flow velocity, while Forchheimer regime is suitable for describing the flow pattern by adding an inertia term on the basis of Darcy regime when the flow velocity is considerably large. Four sintered metal porous air-resistances with different dimensions and porosities are used to perform test for examining the flow rate characteristics that are separated into two regions. Permeability coefficient is first obtained by using the data in Darcy region, and then inertia coefficient is determined by a Gauss-Newton nonlinear least square method with the data satisfying that the Reynolds number is greater than 0.1. Results show that the calculated flow rate agrees with the experimental result, with the error less than 2%. The experimental testing system is able to ensure the permeability coefficient to be measured within a 3% uncertainty, which is sufficient for most applications.

Key words: Flow rate characteristics, Inertia coefficient, Permeability coefficient, Porous media