| As the dispersed phase in the gas-liquid two-phase flow,bubbles make a great influence on the transfer of mass,heat and momentum.It plays an important role in the study of gas-liquid two-phase flow,which connects the macroscopic scale and the nanometer micro scale.In this paper,the high-speed camera method is used to study the rising,deformation and fracture of the bubble in the jet field.At the same time,2D-PIV is used to study the liquid phase single-phase ejection field without dispersion phase.The law of the single bubble breakup should be analyzed by combining them.The jet flow is studied by 2D-PIV.The results show that the jet flow is relatively symmetrical.In vertical direction,the shear rate first increased and then decreased,reaching a maximum where y is 2mm,and the shear rate was 0 when y is 5.2mm.The shear rate of the jet field is more than 100s-1.In the study of bubble crushing process,the bubble diameter has a good linear relationship with the inner diameter of the needle,which bubbles produced by injecting air into the liquid phase through dispensing needles.With the increase of Reynolds number,the crushing probability is increasing.When the Reynolds number is between 5478 and 6279,the bubbles were broken into two daughter bubbles.When the Reynolds number is 7825,the bubble will be broken absolutely.Combined with the jet field information obtained by 2D-PIV,the critical capillary number of bubble breaking in jet field is 0.015.According to the statistics of the bubble breaking position at different velocity,it is found that the bubble is broken in the position of the low shear rate where the flow field the Reynolds number is more than 5699 in the jet flow.However,the bubble is not broken completely in the position of the low shear rate where the flow field the Reynolds number is lower than 5478 in the jet flow.Because the bubble is not only affected by the shear in the jet field,but also influenced by the turbulence velocity fluctuation. |
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