Research On Generation Mechanism And Concentration Prediction Model Of Total Dissolved Gas Supersaturation Downstream Of High Dam Based On Bubble Dynamics

The total dissolved gas of the high dam downstream can develop the supersaturation problem in the sluicing period.It's urgent to solve the environment issue for most of experts.The experiment can testify the major impact factors in the total dissolved gas(TDG)emission.In this paper,a parameter ? can be calibrated through the experiment data and the numerical simulation.The study on parameter analysis of slip penetration model is scarce,and the relevant research of coaxial bubble rise in supersaturated total dissolved gas water is at an elementary stage,so the transfer process of coaxial bubble coalescence was tested by the parameter ?.The main conclusions are as follows:(1)The TDG saturation was higher than 135 % while the pressure was exceeding0.15 Mpa,and its growth rate is between 2% and 5% within 5 minutes.(1)Each impact factor was studied by 36 set of experiments.The results showed that the influence rank in ascending order is the aeration volume,the water height and the pore diameter.And all factors had a positive impact on transferring with increasing the transfer velocity.(2)A new mass transfer formula was set up based on the slip penetration model,and calibrated by No.5 test.The results showed that,with the parameter value increasing,the emission velocity was higher than before.The numerical simulation was closed to the experiments when parameter value equaled to 0.35.(3)The final shape of bubble rise can be predicted by calculating three dimensionless numbers.The slope of TDG concentration was lower than non-coalescence,it indicated that the bubble coalescence produced the surface renewal,but it reduced the mass transfer area,so it had a negative effect on the mass transfer.