Coupled Radiation-Gasdynamic Model for Stardust Earth Entry Simulation

Abstract

A three-dimensional radiative aerodynamic computational simulation has been accomplished for the thermodynamically and chemically nonequilibrium flowfield around the Stardust sample return capsule at an angle of attack. In the early phase of study, the axisymmetric computations using the half-moment method indicate a significant radiative-gasdynamic interaction at high-altitude stages of the reentry trajectory. The radiative heating of the space capsule is studied again according to the preentry trajectory simulation of NASA duplicating the flight condition at an angle of attack of 8 deg. The three-dimensional radiative heat transfer is generated by a spectral multigroup ray-tracing method including the most dominant radiative mechanisms of absorption and emission. The computational results agree very well with data in literature and bring new insights into the interdisciplinary fluid dynamics phenomenon. Nomenclature a j;n , b jn = stoichiometric coefficients of the reaction c p;i , h i = specific heat capacity at constant pressure and specific enthalpy D i = effective diffusion coefficient of species e v;m = specific vibrational energy of m mode J b;! r = blackbody spectral intensity (the Planck function) J ! r;= spectral intensity of heat radiation k f;n , k r;n = rate constants of the forward and reverse reactions ! r = spectral absorption coefficient M i = molecular weight of species p, = pressure and density Q ! r = spectral emission source Q vib = energy source due to vibrational relaxation r = radius-vector of current spatial point S n f;j , S n r;j = rates of the forward and reverse reactions T = translational temperature T V;m = vibrational temperature for m mode of species t = time _ w i = reaction rate for species W j = formation rate for species Vu; v; w = velocity X i = chemical symbol of reactants and products Y i , x i = mass and molar fraction of species , = viscosity and heat conductivity coefficients i , J i = density and mass diffusion flux for species, J i D i grad Y i im = density of species having m mode of vibration = dissipative function = unit vector of solid angle

Fire ‐ II Flight Data Simulations with Different Physical ‐ Chemical Kinetics and Radiation Models

“…The nonequilibrium radiation reduces the standoff distance, and the effect is more pronounced in the later stage of reentry. The maximum disparity is around 10.5% at 1640 s. Meanwhile the equilibrated temperature of the coupled results along the stagnation streamline is also elevated at the later stage of reentry and reaches a value of more than 1000 K. The identical effects of a thinner standoff distance of the radiative cooling of the blunt nose are also observed for the Stardust reentry simulation [10]. …”

“…Such disparities were also shown in a book by Park in the early 1990's [6]. Several recent publications also demonstrate significant influence of chemical and physical kinetics on radiative heating of a new generation of space vehicles [7][8][9][10].…”

Elementary Processes and Kinetic Modeling for Hydrogen and Helium Plasmas

“…In Jupiter atmospheric entry, radiative heating gives a relevant contribution [54,55], especially in regions not exposed to conductive and convective heating. At the same time, the ionization degree is sufficiently high to have appreciable effects of free electrons on flow properties.…”

Spatial Multiphysics Models of the Radiation Gas Dynamics of Super Orbital Re-Entry Space Vehicles

“…In this case one uses an assumption concerning Boltzmann's energy distribution inside some separated degrees of freedom. To verify and validate obtained numerical simulation results several well known calculation and experimental data were used (Fire-II and Stardust) [23,24].…”