This paper reports a set of theoretical expressions for describing the microstructure of multimodal fibrous filter media comprising fibres of different cross-sectional sizes along with the application of such expressions to predict the filtration performance of clean and clogging media for engine intake air filtration. It is found that the overall filtration efficiency corresponds very well with the classical theory of air filtration after suitably modifying the single fibre efficiency and mean fibre diameter. The square of mean fibre diameter is found to be a weighted harmonic mean of the square of fibre diameter of individual component. The single fibre efficiency of multimodal filter media, when expressed as a summation of single fibre efficiencies of individual component of fibres weighted by the corresponding surface area fraction, correlates very well with the experimental results. The evolution of pressure drop is explained satisfactorily based on Berman’s approach after suitably modifying the Davies equation.

中文翻译：

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用于发动机进气过滤的不同尺寸纤维制成的多模态纤维过滤介质的微观结构和颗粒过滤行为

本文报告了一组理论表达式，用于描述包含不同横截面尺寸的纤维的多模态纤维过滤介质的微观结构，以及应用这些表达式来预测清洁和堵塞介质在发动机进气过滤中的过滤性能。发现在适当修改单纤维效率和平均纤维直径后，整体过滤效率与经典的空气过滤理论非常吻合。发现平均纤维直径的平方是单个组分的纤维直径平方的加权调和平均值。多峰过滤介质的单纤维效率，当表示为由相应表面积分数加权的纤维的单个组分的单纤维效率的总和时，与实验结果有很好的相关性。在适当修改戴维斯方程后，基于伯曼的方法令人满意地解释了压降的演变。