Geometric Effects of Flow Restrictions and Configurations on Interfacial Structures in Two-Phase Flow
Open Access
- Author:
- Yadav, Mohan Singh
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Seungjin Kim, Thesis Advisor/Co-Advisor
Seungjin Kim, Thesis Advisor/Co-Advisor - Keywords:
- Flow restrictions
two-phase bubbly flow
interfacial area concentration
void fraction - Abstract:
- This study investigates the geometric effects of flow restrictions and flow configurations on two-phase flow parameters. Experiments are conducted in two distinct experimental setups employing different flow configurations and flow restrictions. In the first experiment, comparison of the effects of 90-degree and 45-degree elbows on interfacial structures and their transport characteristics in horizontal two-phase bubbly flow is investigated. The setup is made out of 50.3 mm inner diameter glass tubes and a double-sensor conductivity probe is used to collect time averaged local data. Experimental results show that both elbows have significant effect on the development of interfacial structures as well as the bubble interaction mechanisms. Furthermore, there are characteristic similarities and differences between the effects of two elbows. While the effect of the 45-degree elbow is evident immediately after the elbow, the 90-degree elbow effect is propagated further downstream of the elbow. Moreover, it is shown that both the elbows induce oscillations in the interfacial structures and two-phase flow parameters, but the degree and the nature of oscillation differ. Comparison of the elbow effect on the axial transport of two-phase flow parameters is also investigated. The second set of experiments is performed in combinatorial two-phase flow facility to study the effects of 90-degree vertical elbow and geometric configuration on two-phase bubbly flow. The elbow has a significant effect on two-phase flow regime transition boundaries at measurement locations downstream of the elbow. Modified two-phase flow regime maps based on the extensive flow visualization studies are suggested for both vertical and horizontal test sections. A four-sensor conductivity probe is employed to measure time averaged two-phase local parameters as the flow develops along vertical upward to horizontal section across the 90-degree vertical elbow. The elbow causes the bubbles to align along the horizontal radius of the pipe cross-section, creating a bi-peaked profile in void fraction and interfacial area concentration. One dimensional transport of area averaged two-phase flow parameters shows that the elbow promotes bubble interaction mechanism.