Abstract: 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.