Influence of a Porous Polyurethane Partition on Hydraulic Characteristics of the Flow and on Flame Front Propagation in an Open Channel

Abstract

The purpose of the research was to experimentally study the influence of a porous polyurethane partition on the flow parameters and on the flame front propagation in front of the partition upon initiation at the open end of the channel. The flame front velocities were determined in a hydrogen-air mixture at atmospheric pressure in a channel open on both sides with an inner diameter of 20 mm. The ratio between hydrogen and air was varied, so that the molar excess of hydrogen varied from 0.3 (ultra-poor mixture) to 1.0 (stoichiometric composition). The pore size varied within 0.3--2.5 mm, which corresponded to the number of pores per inch in the range of 10--80. The coefficients of hydraulic resistance of a polyurethane partition with an open pore type, depending on the size of the pores and the thickness of the partition, were calculated from the pressure loss when the air flow passes through the porous element. The flame front velocity was determined using the shadow method and high-speed survey. Findings of the research show that the optimal value of the thickness of the porous partition, after which the polyurethane partition begins to show filtration properties, in most cases is approximately equal to twice the pore size and the drag coefficient depends linearly on the total thickness of the partition. In this case, the deficit of the flow velocity with increasing thickness increases according to a power law. A qualitative correspondence between the flame front velocity in front of the porous partition and the flow velocity deficit is shown