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2023
Conference Paper
Title
Flow-induced deformation of nonwoven filter media: Experiments, modeling and simulation
Abstract
During operation of filter elements, it is observed that the fluid flow causes deformations of the filter media which can lead to well-known (and undesired) effects like pleat collapse, pleat crowding etc. In such cases, filter designers are facing the additional challenge to provide stabilizing countermeasures such as spacers, supporting ribs and pleat holders without sacrificing too much available media surface area.
Finding a good design by building and testing prototypes can become very costly, so it seems natural to use computer simulations to optimize countermeasures like those mentioned above. However, most simulation models assume “rigid” filter materials. Therefore, suitable models and simulation methods for the Fluid-Porous-Structure Interaction (FPSI) are desired to obtain more realistic predictions of the filter media deformation for a given design variant. This requires a better understanding of the mechanical properties of nonwoven filter media. More precisely, the material laws governing their behaviour when subjected to volumetric forces need to be known.
To investigate this, several media used in liquid filtration were characterized in terms of air permeability and structural mechanics. For the in-situ measurement of the deformation caused by stationary, laminar flow, a suitable test bench was designed and built. The experimental data are used to identify suitable mechanical material laws and the corresponding parameters. These serve as input for the simulation of the flow-induced deformation.
The simulation approach is a coupling of Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM), using the fluid pressure gradient as the mechanical load acting on the filter material. Recent experimental data obtained on the test bench are presented and simulation results are compared to the measurements. The respective advantages of the approaches for practical applications are discussed.
Finding a good design by building and testing prototypes can become very costly, so it seems natural to use computer simulations to optimize countermeasures like those mentioned above. However, most simulation models assume “rigid” filter materials. Therefore, suitable models and simulation methods for the Fluid-Porous-Structure Interaction (FPSI) are desired to obtain more realistic predictions of the filter media deformation for a given design variant. This requires a better understanding of the mechanical properties of nonwoven filter media. More precisely, the material laws governing their behaviour when subjected to volumetric forces need to be known.
To investigate this, several media used in liquid filtration were characterized in terms of air permeability and structural mechanics. For the in-situ measurement of the deformation caused by stationary, laminar flow, a suitable test bench was designed and built. The experimental data are used to identify suitable mechanical material laws and the corresponding parameters. These serve as input for the simulation of the flow-induced deformation.
The simulation approach is a coupling of Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM), using the fluid pressure gradient as the mechanical load acting on the filter material. Recent experimental data obtained on the test bench are presented and simulation results are compared to the measurements. The respective advantages of the approaches for practical applications are discussed.
Author(s)