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Numerical Simulation Air Flow Characteristics Of Fabric Air Dispersion System In Penetration Mode

Posted on:2015-03-28Degree:MasterType:Thesis
Country:ChinaCandidate:X Q XingFull Text:PDF
GTID:2251330428964206Subject:Textile Engineering
Abstract/Summary:PDF Full Text Request
Fiber air dispersion system (FADS), which is new flexible terminal ventilation, has been developing in recent years. Cloth duct made of flame retardant polyester is the critical component of FADS. It can be used in both air transmission and air diffusion. FADS has many advantages such as environment with large area for air spreading, even the air velocity, light, convenience of installation and service etc. Meanwhile, all of bacteria and duct can be easy to strip away from the cloth duct. It is the first choice of ventilation field engineers. Air supply is determined by flow filed in the duct. The structural and property of fiber layer affect the characteristics of the flow field inside the penetration duct. In this paper, the air flow equations and discrete equations in the cloth duct and within the fiber layer were established based on computational fluid mechanics theory. Then the grid of the cloth duct was divided and the boundary conditions and basic parameters were determined. Finally, the pressure distribution and velocity distribution of the gas flow inside the fiber duct was calculated numerically. The results also were experimentally validated.(1) The fiber air dispersion system is regard as an isotropic porous media. The damping was added to air flow equations within the fiber layer. And the standard two equations was used in this model to generate a mathematical model, which was described the characteristics of turbulent flow field. Finally the differential equations become discrete equations based on the finite element method.(2) The porosity of two fabrics used in this paper was figure out26.7%and70.6%, and viscous resistance coefficient and inertial resistance coefficient were got out by experiments.(3) The air velocity on the center line of cloth duct is fast and decreases radially to the surrounding wall. The air velocity and the air pressures on the center line of cloth duct decreases far from the duct’s inlet. It has a return in the closed end and forms vortexes. It result that the air pressures increases in the end of the duct. (4) It is clear that the fabric with porosity of26.7%can be used to the cloth duct. Both of the air pressure and the air velocity on the inner surface of the fiber layer such as fabric with low porosity are evenly distributed. In contrary, those of the fabric with porosity of70.6%decrease quickly. They are close to zero nearby the terminal of the cloth duct.(5) The air velocity on the outer surface of the cloth duct made up of fabric with porosity of26.7%is same to the result of numerical calculation.
Keywords/Search Tags:fiber air distribution system, fiber duct, permeation, porous media, numerical simulation, velocity distribution, pressure distribution
PDF Full Text Request
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