NUMERICAL-SIMULATION OF A SUPERSONIC-FLOW CHEMICAL OXYGEN-IODINE LASER SOLVING NAVIER-STOKES EQUATIONS

The reaction zone structure of a supersonic flow chemical oxygen-iodin e laser (COIL) is simulated solving the two-dimensional Navier-Stokes equations in order to clarify the reaction zone structure and the effe cts of water vapor condensation precisely. A chemical kinetic model co nsisting of 10 chemical species and 21 chemical reactions is used to d etermine the chemical composition of the mixture. The liquid phase is modeled as a number of droplet classes. Each class contains only dropl ets of a certain range of sizes, which is approximated as one average size. The calculation shows that the I-2 gas injected into the singlet oxygen through a two-dimensional slit mixes very slowly and the small signal gain coefficient is high only in a narrow layer where the mole fraction of I(P-2(1/2)) reaches a high value. Nonequilibrium condensa tion takes place during supersonic expansion, generating water droplet s whose size is much smaller than the wave length of COIL. Condensatio n reduces the small signal gain coefficient, since the temperature ris e caused by latent heat suppresses the generation of I(P-2(1/2)).