| Abstract: | A previously studied bubble generator was tested under new operating conditions to provide for millimeter‐sized bubbles. The basic element of the generator is a vortex chamber with water supplied through tangential ducts while gas (air) is introduced in the radial direction. Bubbles with average diameter of 0.5–2.2 mm were produced and registered by high‐speed photography. The correlation between the water‐air flow rate ratio and the characteristic bubble diameter was established and described by a relationship. Pressure oscillations in the exit section of the device were captured for two‐phase flows with fine and coarse bubbles. With a view to applications in membrane filtration and water treatment, the effect of a pin installed in the exit section of the vortex chamber on the pressure oscillations was studied. The pin results in a drastic increase in pressure amplitude, both in the flow without bubbles and in the case of gas supply. |
