The goal of this study is to evaluate the effects of different models for calculating the mixture transport properties on flowfield predictions of ablative heat-shields. The Stardust sample return capsule at four different trajectory conditions is used as a test case for this study. In the first part of the study, the results predicted using Wilke's mixing rule with species viscosities calculated using Blottner's curve fits and species thermal conductivities determined using Eucken's relation are compared to the results obtained using Gupta's mixing rule with collision cross-section (CCS) data. The Wilke/Blottner/Eucken model overpredicts the heat transfer to the surface relative to the Gupta/CCS model by as much as 60%. The Wilke/Blottner/Eucken model also overpredicts the mass blowing rate due to the removal of bulk carbon by as much as 25% compared to the Gupta/CCS model. In the second part of the study, the effects of the mass diffusion model are assessed using Fick's, modified Fick's, self-consistent effective binary diffusion (SCEBD), and Stefan-Maxwell models. The results show that the flowfield properties calculated using modified Fick's, SCEBD, and Stefan-Maxwell models are in good agreement. Fick's model overpredicts the heat transfer and mass blowing rate by as much as 20% relative to the Stefan-Maxwell model.
Digital Object Identifier (DOI)
Alkandry, Hicham; Boyd, Iain D.; and Martin, Alexandre, "Comparison of Models for Mixture Transport Properties for Numerical Simulations of Ablative Heat-Shields" (2013). Mechanical Engineering Faculty Publications. 7.