Modeling of gasdynamic and relaxation phenomena in mixed flow lasers
Abstract
The final state of a mixed laser system can be described by using a kinetic relaxation model and an instantaneous, laminar, or turbulent model. The parabolic approximation of the steadystate NavierStokes equations is used to describe the twodimensional flow of a CO2 + N2 + He mixture. The kepsilon model of turbulence, generally used for boundarytype flows, is used to explain the turbulent transfer of mass, momentum, and energy. The influence of spatial pressure gradients on mixing is analyzed, and the role played by the pressure and translational temperature recovery effects is discussed. It is shown that under the underexpanded conditions, shock and rarefaction waves are generated in the gas flow, with a considerable amount of the vibrational energy that can be lost due to the relaxation processes in these disturbances, while in regular flows, these losses are small, and do not exceed a total of 19%. Calculations of the gain coefficient are given and demonstrate how laser performance can be improved under energy extraction conditions. The influence of the initial conditions (velocities, preturbulence levels, concentrations and temperature) is investigated as well. Results are compared with experimental data and shown to be in good agreement.
 Publication:

Combustion in Reactive Systems; 7th International Colloquium on Gasdynamics of Explosions and Reactive Systems
 Pub Date:
 1981
 Bibcode:
 1981crs..proc...46F
 Keywords:

 Gas Mixtures;
 Gasdynamic Lasers;
 Laser Cavities;
 Molecular Relaxation;
 Cross Sections;
 Gas Pressure;
 KEpsilon Turbulence Model;
 Mathematical Models;
 NavierStokes Equation;
 Two Dimensional Flow;
 Velocity Distribution;
 Lasers and Masers