Numerical Simulation of a Supersonic Flow Chemical Oxygen-Iodine Laser Solving Navier-Stokes Equations

The reaction zone structure of asupersonic flow chemical oxygen-iodine laser(COIL)is simulated solving the two-dimensional Navier-Stokes squations in order to clarify the reaction zone structure and the effects of water vapor condensation precisely. A chemical kinetic model consisting of 10 chemical species and 21 chemical reactions is used to determine the chemical composition of the mixture. The liquid phase is modeled as a number of droplet classes. Each class contains only droplets of a certain range of sizes, which is approximated as one average size. The calculation shows that the I2 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(2P1 / 2)reaches a high value. Nonequilibrium condensation takes place during supersonic expansion, generating water droplets whose size much smaller than the wave length of COIL. Condensation reduces the small signal gain coefficient, since the temperature rise caused by latent heat suppresses the generation of I(2P1 / 2).