非均匀速度来流条件下液体射流喷雾特性

实验研究了非均匀速度来流条件下液体横向射流喷雾特性。实验利用多孔板实现速度的不均匀，应用片光照相得到喷雾中心截面照片，使用相位多普勒粒子分析仪（PDPA）测量液滴的直径和速度。实验结果表明:在非均匀速度来流中，射流的弯曲和破碎机理有所不同，导致穿透深度和雾化特性发生改变。与均匀速度来流相比，正速度梯度来流时射流穿透深度更大，液柱破碎高度增大，浓度场分布更加均匀，射流呈现平抛形态；负速度梯度时喷雾场整体内移，浓度场呈明显分层结构，射流尾迹区增长，射流为坍塌形态。初步提出适用于非均匀速度来流条件下的射流穿透深度经验公式。非均匀速度来流可以改善雾化及均匀度，其中负速度梯度来流时液雾的索太尔平均直径（SMD）最小。 

Spray characteristics of liquid jet in nonuniform crossflow

Spray characteristics of liquid jet in nonuniform velocity distribution crossflow were experimentally studied.The nonuniform velocity distribution was produced by perforated plates，the images of spray were captured with a light sheet and a single lens reflex camera，and a phase Doppler particle analyzer （PDPA） was used to measure droplets diameter and velocity.The experimental results indicated that，in the nonuniform crossflow，the bending state and breakup regime of each jet section were different，resulting in the difference of penetration and spray characteristics.Compared with uniform corssflow，the jets penetrated further into the crossflow when the column breakup height increased，and the concentration distribution was more uniform when the velocity distribution was in positive gradient，in addition，the jet presented a flat thrown profile.When the velocity gradient was negative，the spray field moved inward and presented a stratified structure，the jet wake region elongated，and the profile of jet was in collapse state.Correlations of a liquid jet for nonuniform crossflow are presented.Nonuniform crossflow can improve atomization and uniformity，and Sauter mean diameter （SMD） reaches a minimum value when the velocity distribution is negative gradient.