Study of high Reynolds number pipe flows with porous inserts

Abstract

This paper reports experiments for the flow at the inlet and outlet of a ceramic foam located in a straight pipe and in a pipe with a 1:4 sudden expansion. For the last latter, the foam, with thickness to diameter ratio between 0.15 and 0.60, was located at different distances from the sudden expansion wall. The LDA velocity measurements obtained allowed investigating the influence of the ceramic foam insert on the flow upstream from the porous medium inlet or downstream from its outlet. Three different pore sizes (10, 20 and 60 pores per inch) were investigated for pore Reynolds numbers in the range 20≤Rep≤400, corresponding to pipe Reynolds numbers of 600≤ReD≤5500 (2400≤ReD≤22000 in the pipe section upstream of the sudden expansion). Experimental results include velocity profiles at the foam exit as function of the Reynolds number and foam thickness, and confirm the outlet multi-jet flow structure and the decay of the strongly fluctuating velocity field induced at the foam exit in the flow downstream from the porous medium.