A Numerical Study on variation of Flow Pattern of Fluid Passing through three Different Modified Dump Combustors

In this paper, a numerical study on flow characteristics of fluid passing through a sudden expansion plain dump combustor and modified dump combustors having a central restriction of three different shapes at a certain distance ahead the throat has been carried out. The two dimensional, steady differential equations for conservation of mass, momentum and the governing realizable k-e equations are solved for the Reynolds number 1.2x105, aspect ratio (AR) of 3 and 100% central restriction. The variations of streamline contours, re-circulating zones and axial velocities along the radial distance at various axial positions have been studied. After overall study, it is observed that the adverse pressure gradient between central and wall region at the outlet casing is more. Re-circulation zone (RZ) formation in modified dump combustors is more compared to a plain sudden expansion combustor. The fluctuation of radial profile of axial velocity is more at any location for the fillet shape restriction compared to other two shapes of restrictions (rectangular and hemispherical). The modified combustors may perform in efficient manner in terms of complete combustion and less pollutant emission due to formation of more re-circulating bubbles throughout the outlet casing of the combustor.