Fluid flow pressure drop through an annular bed of spheres with wall effects

A model has been developed to predict the pressure drop for flow through an annular packed bed of spheres at random distribution. Ergun's equation, with a corrected flow velocity, is used. To consider the wall effect in the flow distribution, the annular section was divided into three regions: the external and internal wall regions, and an intermediate one, called transition. To find an average flow velocity, to be used in Ergun's equation, a different treatment has been applied to the wall regions, with respect to the transition region. That was necessary due to the presence of a further wetted area and the distortion on the porosity distribution. Model prediction showed good agreement with experimental data. Experiments were carried out for fully developed turbulent flow of air, at steady state condition, through an annular bed with a radius ratio of 1.369 and a bed to particle diameter ratio of 8.258.