Abstract
In Electro Chemical Machining (ECM) process, generation of air bubbles and the flow separation during processing complicate the flow behavior of electrolyte and decrease the shape accuracy of the product. It is highly important to understand the influence of air bubbles on the separated flow. In this study, the flow characteristics of vertical upward gas-liquid two-phase flow with millimeter-scale bubbles and separation in a rectangular channel were examined. Bubbles were fed to the liquid phase from stainless-steel needles with inside diameter of 0.1 mm. Flow separation is generated by a square rod. The liquid velocity was measured using the PIV and the bubble shape was detected by the shadow image technique. It was found that mean velocity profiles of the bubbly flow were steep near the wall and mainstream was flat in the main stream. Furthermore, the reattachment length was reduced by increasing the void fraction.
