The Chemical Energy Accomodation process occurring to gas atoms recombining catalytically on a solid surface is briefly presented. Due to the relevance this phenomenon might have for Thermal Protection Systems heat loads, an analysis of experimental data and recent models accounting for it is done.Information on the Chemical Energy Accomodation Coefficient j3 available so far from simple Langmuir-Hinshelwood or Eley-Rideal models is still not sufficient to draw final conclusions in regard to its behaviour with temperature and pressure, even for pure metals and SiO^-Using a hypersonic flow solver, a parametric analysis of the effect of varying /? is presented for nickel coated bodies past hypersonic air flows; catalytic boundary conditions have been modified to account for incomplete chemical energy accomodation. Effects on body heat load, gas temperature and degree of dissociation are examined. Large effects have been found for thermal loads whereas modest were the effects on gas composition. 'Research Engineer, Nomenclature c p specific heat at constant pressure, J/kg K D dissociation energy, J/mole T> s multi-diffusion coefficient, m 2 /s e total energy per unit mass J/kg ev vibrational-electronic energy per unit mass J/kg h enthalpy, J/kg h° formation enthalpy, J/kg k tr thermal conductivity for translational and rotational energy, J/m s kv thermal conductivity for vibrational and electronic energy, J/m s L body main dimension, m Ma Mach number n coordinate perpendicular to the body surface, m p pressure, Pa Q energy, J/mole q heat flux, W/m 2 T temperature, K u velocity vector X s molar fraction of s chemical species Y s mass fraction of s chemical species /? chemical energy accomodation factor e surface emissivity factor 7 energy-transfer catalytic recombination coefficient 7' atomic recombination coefficient [i mixture viscosity 9 surface coverage: ratio between $ of occupied and total $ of available sites on the catalyst surface p mass density, kg/m 3 cr Stefan-Boltzmann constant W/ m 2 K 4 Subscripts ads adsorption 9 gas R radiative Downloaded by MONASH UNIVERSITY on July 31, 2015 | http://arc.aiaa.org |