
Accession Number : AD0697974
Title : ACCURACY OF DIFFERENTIAL APPROXIMATION FOR RADIATIVE IONIZATION IN COLD PRECURSOR OF AXISYMMETRIC DETACHED SHOCK,
Corporate Author : BROWN UNIV PROVIDENCE R I DIV OF ENGINEERING
Personal Author(s) : Pirri,Anthony N. ; Clark,Joseph H.
Report Date : SEP 1969
Pagination or Media Count : 30
Abstract : Radiative ionization in the cold precursor of the shock preceding a blunt body immersed in a hypersonic monatomic gas flow is studied using the MilneEddington type differential approximation. In order to assess the accuracy of the differential approximation for a multidimensional, axisymmetric geometry, the results are compared with earlier work that presents an exact formulation. The precursor gas is nonemitting with a prescribed frequency dependent absorption coefficient, and the governing differential equation describing the radiation in the precursor is the (elliptic) Helmholtz equation; specification of the boundary conditions pose an interesting dilemma. An integral formulation is proposed and the resulting integral equation is solved to yield the spectral radiant energy density. Calculations of the volumetric photon absorption and the degree of ionization for argon in the near precursor are presented for a downstream degree of ionization on the stagnation streamline of 0.8, an upstream temperature of 300K, and an upstream pressure of .001 atm. The results are found to be sufficiently accurate for many purposes when the influenced point is only a few photon mean free paths from the surface and is close to the shock axis. (Author)
Descriptors : (*GAS IONIZATION, *SHOCK WAVES), (*BLUNT BODIES, HYPERSONIC CHARACTERISTICS), ARGON, PHOTONS, DIFFERENTIAL EQUATIONS, AXIALLY SYMMETRIC FLOW, APPROXIMATION(MATHEMATICS), HEAT TRANSFER, ELECTRON DENSITY, ACCURACY
Subject Categories : Aerodynamics
Fluid Mechanics
Plasma Physics and Magnetohydrodynamics
Thermodynamics
Distribution Statement : APPROVED FOR PUBLIC RELEASE