Collision and coalescence among drops is an important phenomena in gas/drop two-phase flows. To study change of number of drops caused by collision and coalescence,a special flow field is considered in which liquid phase consists of two classes of drops with big or small sizes. Probability for collision and coalescence between a big drop and a small drop is derived. Considering three factors of immigration,emigration and collision of drops,a model of birth-death process is proposed for number of drops located in a fixed observation region,and relevant unconditional probability model equation is deduced. Finally,stationary distribution is obtained. As an illustration,mass creament of a falling rain drop is calculated.

Cryosorption of oxygen produced in chemical oxygen iodine laser(COIL) is considered. From the view point of mass conservation, a linear relation between gas pressure gradient and gas velocity is used with which gases flows through a zeolite porous bed is obtained. An adsorption balance equation, describing relation of components in gas flow and adsorped components,is established with adsorption dynamics equation. Henry relation is employed as isothermal equation. A set of cryosorption model equations is solved numerically. Oxygen concentration evolution,and long time character of concentrations are given.

To investigate mechanism of TUDOG(transeverse uniform singlet oxygen generator),a chemical reaction model is made to describe physical and chemical performances of Cl₂/He mixed gases transversely traveling into a falling BHP(KOH,H₂O₂,H₂O)drop field.Numerical computation is carried out.In two-phase flows,exchange of mass and momentum between two phases is considered.One set of 2-D gas-phase flow equations are solved with SIMPLEC scheme.Simulation results agree well with experiments provided in references.It is found that chlorine utility and singlet oxygen yield decreases with increase of gaseous inflow speed,and increases with speed of falling drops.Absorb and utility of chlorine mainly takes place in reactive region upstream.

To investigate mechanism in TUDOG(Transeverse Uniform Droplet Oxygen Generator),a one-dimensional chemical reactive flow model is established to describe physical and chemical performance as mixed Cl₂/He gases passing through BHP(KOH,H₂O₂,H₂O)droplet field transeversely.Gas-phase flowfield is approximately considered as 1-D homogeneous flow according to incompressibility hypothesis.Chemical reaction in liquid droplet is described by reactive-diffusion equations with 4 gasous components.Concentration of gasous components are described with convective-diffusive equations. Droplets are gasous source or sink. It is shown that chlorine utility,singlet oxygen yield and generator efficiency are close to experiment results.The model is verified in simulating interactions between mixing gases and BHP droplets.