Accession Number : AD0677012

Title :   FLOW WITH COUPLED RADIATIVE AND VIBRATIONAL NONEQUILIBRIUM IN A DIATOMIC GAS,

Corporate Author : STANFORD UNIV CALIF DEPT OF AERONAUTICS AND ASTRONAUTICS

Personal Author(s) : Gilles,Scott E.

Report Date : SEP 1968

Pagination or Media Count : 221

Abstract : A theoretical model for the interaction of radiative and vibrational rate processes in the flow of an infrared-active diatomic gas is developed, with specific application to radiative acoustics and to flow through a normal shock wave. Macroscopic equations of radiative transfer and vibrational relation are obtained, that, while retaining the essential features of the microscopic physics, are simple enough to incorporate usefully with the conservation equation of gas dynamics. The transfer equation is linearized about an equilibrium reference state in a plane-parallel geometry. The analysis is then able to retain the essentially nongrey spectral character of the radiative field because the linearization allows the integration over spectral frequency to be carried out independently of the integrations over space. For application in acoustics, the foregoing results are combined with the linearized vibrational rate equation and linearized equations of unsteady, inviscid flow. This leads to a single, sixth-order acoustic equation for a radiating, relaxing gas, which contains the earlier equations for vibrational or radiative nonequilibrium alone as special cases. The consequences of coupling between radiative and molecular nonequilibrium are explored in detail by an analytical, perturbation solution for the flow through a normal shock wave. The relative importance of the radiative process for a given shock strength and upstream temperature increases with decreasing upstream pressure. (Author)

Descriptors :   (*GAS FLOW, *SOUND), (*THERMAL RADIATION, GAS FLOW), SHOCK WAVES, MOLECULAR ENERGY LEVELS, INFRARED PHENOMENA, CARBON MONOXIDE, EQUATIONS OF MOTION, VIBRATION, TRANSFER FUNCTIONS, ACOUSTICS, INTERACTIONS, PERTURBATION THEORY, THESES

Subject Categories : Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE