No abstract

Studies have shown that both char particle diameter and apparent density vary during char conversion at high temperatures. To account for such variations, power-law expressions have been used to correlate r p /r p,0 and ρ p /ρ p,0 with m p /m p,0. The parameters in these relations are constants, thus this approach fails to account for variations in the functional relationship between mass, size, and apparent density as mass conversion proceeds. To overcome this limitation, a model for the mode of particle conversion has been developed that permits the variation in size and apparent density with mass loss to depend upon the Thiele modulus, which varies during char conversion. The rate with which the particle radius decreases is shown to be given by the ratio of the time derivative and the spatial derivative of the particle density at the surface of the particle. The model presented can be used to describe the mode of conversion of reactive porous particles in a range of different applications such as entrained flow gasifiers, pulverized coal burners and circulating fluidized bed combustors. There are no free tunable parameters in the model.

In this work, conversion of char is studied in a simulation code that includes a simplified heterogeneous adsorption-desorption reaction mechanism for char chemical reactivity and uses GRI-Mech 3.0 as the chemical kinetic mechanism that describes the impact of homogeneous reactions. Besides sub-models for the consequences of chemical reactions, a mode of char particle conversion sub-model is included that describes how particle size and apparent density vary with mass loss as well as a radiation sub-model that describes the radiant exchange of energy between the char particle and surrounding particles and walls. The code is transient and zero dimensional in space, and designed to be used both as a stand-alone gasification/combustion code and as a sub-model for heterogeneous reactions of solid particles in a CFD code.

The research has been dedicated to developing a virtual crashworthiness platform for large advanced aircraft structures when subjected to water ditching incidents. A numerical design tool, incorporating fluid-structure interaction analysis module, was created to assess damage tolerance in future aerospace design concepts to help with the prognosis of structural failure. To accomplish this, an experimental water impact set up was used to calibrate and validate the developed detailed virtual model. Specific data acquisition techniques implemented allowed for the capture of strain distribution and impact energy dissipation, used to validate the simulation platform.