Owing to high-turbulent and shear flow caused by the converging-diverging geometry, Venturi channels can serve as bubble generators to produce fine bubbles efficiently. Taking the advantage of simplicity in structure, high reliability, and low power consumption, Venturi-type bubble generators have broad application potential in various fields. Under a specified flow condition, the performance of a Venturi-type bubble generator is highly dependent on its geometric parameter. In the present work, an investigation was carried out to illustrate the effect of the throat sizes (W_th = 1 mm, 2 mm, and 4 mm) on the performance of rectangular Venturi channels for producing fine bubbles. Bubble deceleration, residence, and breakup in the diverging sections were particularly investigated and compared. Bubbles experienced dramatic deceleration and intense breakup in small Venturi channels like that in conventional size ones. The Vortex region in the diverging section moved to upstream with decreasing the throat size, resulting in more intense bubbles deformation and breakup. In Venturi channels of W_th = 2 mm and 4 mm, bubbles were always collapsed into several fragments after chaotic shape oscillations in the diverging section. For the case of W_th = 1 mm, bubbles were split by the strong liquid jet in their wake regions once they entered the diverging section. The liquid jet induced stronger vortex flow and significantly prolonged the residence time of the bubbles in the diverging section, which was beneficial to surface energy accumulation to trigger continuously shearing-off processes or bubble breakup. Overall, the Venturi channel of W_th = 1 mm presents the best performance, producing the smallest and most uniform fine bubbles with average diameter of 0.2 – 0.3 mm at the liquid velocity of U_th = 6.5 – 10 m/s.

由于收敛-发散几何结构引起的高湍流和剪切流，文丘里通道可以作为气泡发生器有效地产生细小的气泡。文丘里型气泡发生器具有结构简单、可靠性高、功耗低等优点，在各个领域具有广阔的应用潜力。在规定的流动条件下，文丘里型气泡发生器的性能高度依赖于其几何参数。在目前的工作中，进行了一项调查来说明喉部尺寸的影响（W _th = 1 毫米、2 毫米和 4 毫米）关于矩形文丘里通道用于产生细气泡的性能。特别研究和比较了分流段中的气泡减速、停留和破裂。在像传统尺寸的小文丘里通道中，气泡经历了剧烈的减速和剧烈的破裂。发散段中的涡流区随着喉道尺寸的减小而向上游移动，导致气泡变形和破裂更加强烈。在 W _th  = 2 mm 和 4 mm 的文丘里通道中，气泡在发散部分的形状混乱振荡后总是坍塌成几个碎片。为W的情况下_个 = 1 mm，气泡一旦进入发散部分，就会被尾流区域中的强液体射流分裂。液体射流引起更强的涡流，显着延长了气泡在发散段的停留时间，有利于表面能的积累，引发连续的剪切过程或气泡破裂。总体而言，W _th  = 1 mm的文丘里通道表现出最佳性能，在 U _th  = 6.5 – 10 m/s的液体速度下产生平均直径为 0.2 – 0.3 mm 的最小和最均匀的细气泡。