One Group Interfacial Area Transport Modeling of Horizontal Bubbly Flow with Restrictions: 90-degree or 45-degree Elbow
Open Access
Author:
Talley, Justin D
Graduate Program:
Nuclear 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:
interfacial area transport equation geometric effects horizontal two-phase flow
Abstract:
The one-group interfacial area transport equation applicable to air-water horizontal bubbly flows with a 90-degree or 45-degree horizontal elbow is developed. The local database provided by the U.S. Nuclear Regulatory Commission is used to benchmark the present models. In total, 105 area-averaged data points obtained in 15 different flow conditions for both the 90-degree and 45-degree experiments at four and three different axial locations, respectively, are employed for model evaluation. A predictive model for the characteristic pressure loss due to the flow restriction is developed and used as a constitutive relation for the pressure gradient term in the model. The non-uniform distribution of two-phase flow parameters due to both the flow orientation and the flow restrictions is taken into consideration in the present model by a distribution parameter analogous to covariance. In general, it is found that the Velocity Gradient (VG), Random Collision (RC), and Pressure Drop (PD) play the major roles for interfacial area transport in low void fraction flow conditions, whereas the Turbulence Impact (TI), Random Collision (RC), and Pressure Drop (PD) mechanisms become dominant as the void fraction increases. Overall, the present model predicts the data well with the average percent difference of ±20%.
