NUMERICAL AND EXPERIMENTAL STUDY ON TWO-PHASE FLOW IN A SWIRLING FLOW BUBBLE GENERATOR

• Main Author: Imam Arif, Muhammad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/81215
• Institution: Institut Teknologi Bandung

Micro/nanobubble generation technology has attracted widespread attention in recent years due to its potential in various fields, such as; drinking water and wastewater treatment, agriculture, material technology, medicine and medicine, energy systems and food industry . The hydrodynamic cavitation method using a swirling flow is a superior micro/nanobubbles generation method compared to other methods due to its higher efficiency, lower cost, and ability to operate at various pressures and flow rates. Research and development are being done to obtain better bubble generator designs. In this study, experiments and numerical studies were conducted to investigate the two-phase flow in a swirling flow bubble generator and the dimensional properties of the generated microbubbles. Computational Fluid Dynamic (CFD) combined with the Population Balance Method (PBM) was used for the numerical simulation. The transient solver was used in the simulation with mixture model for the twophase flow, Turbulent model for the aggregation kernel and Lehr model for the breakage kernel. The two-phase flow in the swirling chamber and bubble generator outlet was recorded using a high-speed camera at a varied flow rate ratio (Qw/Qg). The bubble size distribution obtained was analyzed using the Particle Image Velocimetry (PIV) method. Two-phase flow modelling with the CFD-PBM method utilizing the transient solver, the mixture model, the Turbulent model for aggregation kernel, and the Lehr model for breakage kernel has been confirmed to yield good predictions of bubble size distribution and two-phase flow characteristics in the swirling flow bubble generator. The bubble size distribution obtained from the experimental results shows an increase in the generated microbubbles by 12-19% when the water flow rate increases from 20 to 32 L/min. Meanwhile, the change in the oxygen gas flow rate from 0.5 to 1 L/min did not have a significant effect.