Numerical simulation of dump combustor with auxiliary fuel injection

Abstract

Solutions of the steady, two-dimensional Navier-Stokes, thermal energy, radiation flux, and species conservation equations have been computed for a dump combustor geometry with downstream constriction. The equations are solved in the conservative finite-difference form on a nonuniform rectilinear grid of sufficient resolution to capture the momentum/thermal boundary layers accurately. The numerical procedure, SIMPLEST, which is a variation of SIMPLE, is used to ensure more rapid convergence. A κ−ε model is incorporated for the enclosure of turbulence with a wall function. The combustion model, ESCRS (extended simple chemically-reacting system) with eddy break-up model for the reaction rates of species conservation equation or energy equation is also used. For the good destruction of hazardous waste, it is effective that the waste is injected in the recirculation zone of high temperature with the condition not disturbing the combustion cavity. Excess oxygen from a lean core flame can be effectively utilized for waste destruction with the hydrocarbon waste injection as fuel-rich condition. The core flame has a significant impact on the structure of recirculation cell, in some cases completely changing the nature of the flow within the cavity. The optimum velocity of waste injection exists for the highest temperature at the recirculation zone. A premixed flame type for the auxiliary fuel is good for high temperature and long residence time to be large cavity in the recirculation zone.