扰流型喷枪顶吹管内特殊两相流流型实验

Experiment study on the top-blowing special two-phase flow patterns in the pipe of turbulent-spray gun

主要对自主设计的渐缩管、渐扩渐缩管、螺旋管和四孔管进行水-空气两相流混合顶吹实验,并得出了扰流型喷管的管内流型变化规律。实验通过对可视化特殊喷管内的气液两相进行高速拍摄,并调节水与空气两相各自的体积流量,获取不同喷管中出现的特殊流型照片及视频。实验结果表明:在表观气速和表观液速变化时,除渐缩管外,其他特殊喷管的流型转变均有一定规律性;渐扩渐缩管内截面半径变化较大,易产生环状-搅拌流,并有典型泡状流出现,螺旋管由于轴向环流速度的影响,会产生大密度泡状流并逐渐过渡到有旋流趋势的环状流型,特殊结构的四孔管中流型较稳定,短暂出现泡状流、弹状流后形成稳定环状流。四孔管的设计最利于冶金熔炉中柴油-氮气混合两相流喷吹,形成的气泡群中单个气泡直径较小,柴油被充分细化打散,渣层中的还原反应更充分,能有效提高柴油对渣层中磁性铁的还原率。

This paper focused on the design of tapered tube,converging diverging tube,spiral tube and the four-hole tube for gas-liquid two-phase flow mixing top-blowing experiments. The variations of flow patterns in the pipe of turbulent-spray gun were obtained. The experiment investigated the high-speed photography through the two-phase mixture of gas-liquid in the visualized special nozzle, the adjustment of volume flow in each phase,and visualization of the special flow patterns in different nozzles. The experimental results showed that the following：the flow pattern transition changed regularly with the changes in superficial gas velocity and superficial liquid velocity in all tubes except for the tapered tube;With the great change in section radius in the converging diverging tube, annular-churn flow could be easily produced,and typical bubble flow could also exist;under the influences of the axial velocity,spiral tube could have a high density of bubble flow pattern and annular flow and slug flow for a short period of time,and then form steady annular flow;the design of four-hole pipe was beneficial to two-phase flow of diesel-nitrogen mixture in metallurgical furnaces, the single bubble formed in this type of tube was smaller in diameter,resulting sufficiently scattered diesel fuel,the reduction reaction of slag layer was therefore more efficient with higher,reaction rate of magnetic iron in diesel.