Three dimensional simulation of air permeability of single layer woven structures

Abstract

The paper deals with a CFD based study of the transverse permeability of a textile woven structure. The reported numerical investigation is preconditioned by both previous experimental and CFD study on jet systems. It is also based on detailed experimental investigation of the porous structure of single layer woven fabrics, made of staple fiber yarns. The flow in through-thickness direction of the woven structures is presented as jet systems, issuing from set of orifices. Two different types of jet system (3×3 jets and 5×5 jets) with two types of jet cross sections (square and circular), corresponding to two different woven structures, are simulated. An analysis is made in terms of the structure of the woven fabrics (area and shape of the interstices between the threads), the parameters of the flow passing through the textile (velocity profiles and velocity fields through isosurfaces), the role of the type of the jet systems, representing the flow and the influence of the shape of the interstices between the threads on the flow pattern. It was found that the applied approach could be effectively used for studying of the transverse permeability of the woven fabrics.

Computational modeling and experimental validation of the air permeability of woven structures on the basis of simulation of jet systems

“…It was found in our previous work 18 that there is no difference either in the numerical results, or in the required central processing unit (CPU) time in the simulation of the air flow, between jet systems with circular and square openings. Therefore, the choice of the shape of the pores would depend on the personal preference of the researcher and on the type of the grid used, which has to assure “high quality” of the control volumes, convergence promptness, etc.…”

“…18 It was found that the fine grid gives best results and it was selected for the present investigation as well.…”

“…These dimensions were established on the basis of preliminary simulations, as a compromise between the required CPU time and the necessary flow development. 18 A structured grid of hexahedrons was used, as depicted in Figure 4. Rhe numerical details for the meshing of each of the simulated samples are shown in Table 3.…”

“…The current study is based on systematic experimental research on jet systems 19–21 and experimental investigation of the pores’ morphology and distribution in woven structures, 14 as well as a numerically tested method for CFD simulation of the air permeability, based on jet systems’ theory. 18…”

“…In our previous work, a new method for simulation of the air permeability of woven structures was introduced and tested. 18 The method is based on an approximation of the air flow, passing through the woven fabric, as an “in-corridor”-ordered jet system. Different geometries (circular and square shape of the pores) and configurations (3 × 3 and 5 × 5 jets), as well as types of grids (coarse, fine and hybrid), were studied.…”