Characteristics of multi-phase flow with particle evaporation in a combustor with counter-flow injection

Abstract

Seed particles are added to a high temperature reacting flow to achieve the desired electric conductivity for magnetohydrodynamic (MHD) power generation. The evaporation rate of the see particles and the uniformity of the seed vapor distribution in the reacting flow are major factors affecting the performance of the MHD system. An integral reacting flow (IRF) computer code was used to calculate the multi-phase flow characteristics in an MHD combustor and predict the optimum operating conditions of the combustor. The IRF code is a general hydrodynamics computer code for multi-phase, two dimensional, steady state, turbulent, and reacting flows, based on mass, momentum, and energy conservation laws. A unique integral reaction submodel in the IRF code enhances numerical convergence while preserving the major physical effects of the complex combustion processes. The combustor is a rectangular channel in which a mixture of fuel gas and seed particles enters from one end and exits at the other, while the oxidizer is injected from the sides. The major findings of a parametric study included: (1) the seed particle evaporation rate varies for different oxidizer injection angles; (2) the optimal evaporation rate was found at an injection angle around 130°; (3) the seed particle size had a major effect on particle dispersion and vapor mixing; (4) seed particles with a diameter of 34 μm or larger were only partially vaporized in the combustor, and the seed vapor distribution at the combustor exit was highly non-uniform; and (5) significant particle deposition was found on the side walls upstream of the oxidizer injection slots. Theoretical predictions were in general agreement with experimental trends.