Study On Resistance Characteristics Of Fibrous Porous Media

Fiber filter filtration resistance is an important parameter affecting the filtration performance.In previous studies pressure loss prediction models were established on the basis of regularconfiguration of fiber model, i.e., simplify the configuration of bending, overlapping, twisting inthe real fiber filter medium into regularly distributed cylindrical fibers. Regularly distributedmodels could not embody the effects of fiber microstructure on pressure loss and it also could notreflect fiber internal structure influence (such as the arrangement, pore connectivity,inhomogeneity) on pressure loss. This simplification will cause certain prediction error, which willcause a big limitation. With the development of computer technology, we established atwo-dimensional random distribution fiber model to reflect the real fiber distributioncharacteristics. At the same time, we introduces the concept of fractal dimension and tortuosity toimprove the precision of pressure loss prediction. The fractal dimension is used to characterize theirregularity of fiber distribution. Taking fiber distribution into consideration when we research thefilter pressure loss, we will get more accurate results. The main purpose of introducing tortuosityis to make some necessary corrections of permeability, which will be more close to the actualsituation.In this paper we use AUTOCAD VBA program to create a series of virtual filter mediumwith different structure parameters, then use CFD technology to simulate its flow field and theimage fractal dimension calculation software FRACTALFOX to calculate the fractal dimension ofthe virtual filter medium. After the analysis of the data sorting, we get the fractal pressure lossexpression of two-dimensional models.To verify the reliability of two-dimensional models, we created3d fiber random distributionmodel, this model can truly reflect the internal characteristics of fiber filter medium, includingbending, overlapping and twisting. After comparison, the the expression of two-dimensionalrandom distribution fractal pressure loss were basically agreement with3d model. Finally on thebasis of numerical simulation, experiments were conducted to verify the two-dimensional randomdistribution fractal reliability of pressure loss expression.