Abstract
A simplified numerical model for analyzing the evaporation processes in porous media for gas turbine applications has been developed. Evaporation of a pointwise -injected kerosene spray in a carbon -carb on porous medium is considered. The computational model consists of a two -dimensional domain of dimensions 20.32x4.04 cm. A control -volume based discretization method is adopted to solve the governing equations. The porous medium offers resistance to th e flow of air -fuel mixture and is modeled as a momentum sink. Non -Darcy flow in porous medium is considered and the viscous and inertial contributions are evaluated using a modified Ergun equation. The transient and conduction flux terms in the energy eq uation are modified to account for the heat transfer in porous medium. Energy feedback from combustion porous media is also simulated using a source term. The effects of porous medium temperature, fuel flow rate, air inlet temperature and porous medium g eometry on the evaporation of spray have been analyzed. For the size under consideration, a porous medium heat source of 642 W is required to achieve 97 % complete evaporation for an air inlet temperature of 473 K. The concentration of fuel vapor is foun d to be higher in the core region due to the nature of point injection. Simulations using different flow rate conditions show that a stronger heat source, in turn higher energy feed back, is required to attain complete vaporization. Approximately a 62 % stronger heat source is required when the fuel flow rate is increased from 0.24 to 0.48 mg/s. The increase in air inlet temperature is found to accelerate the evaporation process. At higher air inlet temperatures (573 K), the fuel is vaporized as soon as it gets injected. Evaporation characteristics are not found to vary much with porous medium geometry, as the porous medium is modeled as a momentum sink. Thermal effects of porous media are found to be more dominant in this study.
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