Q2A one-dimensional tangent slab radiative transport solver is developed to model radiation in nonequilibrium hypersonic flows. The solver is line-by-line accurate and (by making use of attached spectral databases) efficient, allowing for direct coupling to hypersonic computational fluid dynamics codes. Modifications to the spectral databases include a hybrid line-by-line-gray solver and a molecular cross-section method based on the assumption of a single representative temperature. These modifications decrease computational costs to allow for tight flow coupling hypersonic computational fluid dynamics solvers, but they maintain line-by-line accuracy. The radiation code is verified by comparison with nonequilibrium air radiation, an established radiation solver. The solver is then integrated into the continuum computational fluid dynamics solver data-parallel line relaxation, and coupled simulations are performed for the flowfields of the Stardust sample return capsule and the Orion crew exploration vehicle.
NomenclatureB 1 = single-temperature upper state population parameter B 2 = single-temperature upper-lower state ratio parameter c = speed of light, m=s, or mass fraction E = total emission energy, W E b = blackbody emissive power, W=m 3 A E n = exponential integral of order n F = state rotational term energy G = state vibrational term energy h = Q3 Planck constant; 6:6261 10 34 J=s i = line index I b = blackbody function, or Planck function, W=m 3 A sr I = spectral intensity, W=m 3 A sr J = radiosity, W=m 2 J U = upper state rotational quantum number k = Boltzmann constant; 1:3807 10 23 J=K N = number density, m 3 n = number of cells n s = total number of species s q = heat flux, W=m 2 Q VR U = upper state total partition function S = source function W=m 3 A sr T = total temperature, K T e = free electron temperature, K T r = rotational temperature, K T t = translational temperature, K T v = vibrational temperature, K V = cell volume, m 3 v = velocity, m=s V U = upper state vibrational quantum number w = line width, Å X = x-cartesian coordinate, m Y = y-cartesian coordinate, m z = distance in body-normal direction, m = Goulard number, or radiative cooling parameter = wall emittance " = emission coefficient, W=m 3 A sr " c i = emission constant, W= A sr max = maximum absorption coefficient in spectral band, m 1 = absorption coefficient, m 1 = wavelength, Å = density, kg=m 3 = optical thickness = line shape function r q r = divergence of radiative heat flux, W=m 3 Subscripts a = atomic c = at line center, or convective e = electronic i = line index L = Lorentz width, lower state m = molecular r = radiative s = species index tot = sum over all species U = upper state V = Voigt width = at a given wavelength, or per unit wavelength 0 = at boundary 1 = term due to true absorption 2 = term due to induced emission 1 = freestream parameters
