Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
EXPERIMENTAL ANALYSIS OF DOWNWARD VERTICAL AIR-WATER ANNULAR FLOW
Submission Author:
Ana Luiza Beltrão Santana , PR
Co-Authors:
Ana Luiza Beltrão Santana, Eduardo Nunes dos Santos, Rafael Fabricio Alves, Dalton Bertoldi, Marco Jose Da Silva, Moisés Marcelino Neto, Rigoberto Morales
Presenter: Ana Luiza Beltrão Santana
doi://10.26678/ABCM.COBEM2021.COB2021-1415
Abstract
Annular flow is characterized by a continuous, fast-moving gas core with a liquid film wetting the pipe wall. This flow pattern has a wavy interface whose waves were formed by the high interfacial shear stress between the phases. The literature shows an extensive number of studies for upward vertical annular flows and a lack of interest in downward annular flows. Regarding those latter, the majority of the works use limited experimental apparatuses with regard to the length–to-diameter ratio (L/D). Therefore, because of this restriction, a flow conditioner that induces the annular flow patterns is frequently adopted. It is known that depending on the type of flow conditioner the characteristics of the interfacial structures of the two-phase flow pattern and the trend of the flow to evolve in the downstream axial direction can be influenced. In this regard, experiments to analyze the main characteristics of downward vertical air-water annular flow in a 26-mm ID, 14-m length pipe were carried out. Tests using two different types of flow conditioners to evaluate the influences of the phase injection on the features of the liquid film and downstream evolution of the flow at two test sections (placed at 90D and 335D from the flow conditioner outlet) were performed. A non-intrusive conductance sensor and a high-speed camera were deployed in the test sections to measure the characteristics of the liquid film. Twenty-one combinations of air and water superficial velocities ranging from 10 m/s to 20 m/s and 0.05 m/s to 0.25 m/s, respectively, were investigated. Analysis of the liquid film time series provided liquid film features such as the average film thickness, liquid film roughness, disturbance wave velocity, and disturbance wave frequency. Results showed variations for all annular flow features evaluated in the axial direction. Besides, the flow conditioner that not induces the annular flow, affects the flow at the test section closer to phase entrance (90D).
Keywords
downward vertical, Annular flow, liquid film, flow conditioner
