Numerical investigation into the loading behaviour of filters operating in the diffusional and interception deposition regimes
journal contributionposted on 2012-12-13, 11:42 authored by Sarah DunnettSarah Dunnett, Charles F. Clement
Using a previously developed theory, which allows for changes in gas flow from deposit growth, calculations are performed for deposition on an initially cylindrical fibre. The deposit is given a specified porosity through which the flow is calculated from Darcy's equation using the Beavers and Joseph (1967) boundary condition at the outer boundary. Results are obtained for different porosities φ the volume fraction of space in the deposit, for flow conditions such that deposition occurs by the mechanisms of diffusion and interception, but not impaction (Stk<1). Dependencies given in the literature of the deposit permeability on φ are examined. The dominant mechanism is determined by the value of the parameter, s=R/δ where R is particle to fibre radius ratio and δ is the non-dimensional thickness of the flow diffusion layer. Where diffusion dominates, s<1, increase in porosity does not significantly increase deposition, apart from the effect of its lower density. Where s>1 and interception dominates, deposition increases with increase in φ and is significant for φ ≥0.9 where more streamlines pass through the deposit. The shape of the deposit remains peaked at the front of the fibre, at the forward stagnation point, but, if a deposit has an initial flat front, it grows into a shape peaked away from the stagnation point, as observed by Kanaoka et al. (1986). Possible reasons for this behaviour are discussed.
- Aeronautical, Automotive, Chemical and Materials Engineering
- Aeronautical and Automotive Engineering
CitationDUNNETT, S.J. and CLEMENT, C.F., 2012. Numerical investigation into the loading behaviour of filters operating in the diffusional and interception deposition regimes. Journal of Aerosol Science, 53, pp. 85 - 99.
- AM (Accepted Manuscript)
NotesThis article was published in the Journal of Aerosol Science [© Elsevier] and the definitive version is available at: http://dx.doi.org/10.1016/j.jaerosci.2012.06.008