Abstract
Gas-liquid annular flow is widely used in many industrial applications such as petroleum, chemical, and nuclear engineering. The feature parameters of liquid film in the annular flow are of great significance to understand the flow characteristics and measure the flow precisely. For the annular flow, the circumferential features of liquid film are more important than the axial features to acquire abundant flow structures and reveal the flow mechanism. In the paper, a measurement platform based on the laser-induced fluorescence (LIF) and virtual stereo vision sensor is presented. The virtual stereo vision sensor comprises a high-speed camera and two optical reflection sets, which can acquire the liquid film from two views simultaneously and reconstruct the features of liquid film. Image processing techniques are proceeded with to extract the feature parameters of liquid film; then the circumferential flow characteristic can be reconstructed by views transformation and fusion. The flow characteristic based on the thickness distribution is analysed. The experimental results show that the method is valid and effective, which can give a more detailed and accurate description for the liquid film in annular flows.
Highlights
The annular flow is one of the important flow patterns in gasliquid two-phase flow
According to the analysis of the virtual stereo vision sensor in Section 2.2, the circumferential liquid film of the pipe was viewed from a certain angle, and it is necessary to proceed with the 40∘ projection transformation to simplify the subsequent fusion and reconstruction
An optical technique based on the laserinduced fluorescence (LIF) and virtual stereo vision sensor is presented to measure the circumferential liquid film in annular flow
Summary
The annular flow is one of the important flow patterns in gasliquid two-phase flow. The flow pattern is characterized by the presence of a thin liquid film flowing along the wall of the tube and surrounding a fast-moving gas core. The cross-sectional images of the liquid film are more important than the longitudinal images to reveal the unsymmetrical flow characteristic of interfacial wave and flow mechanism, especially under high pressure, but the circumferential measurement is more difficult to achieve. The paper aims to reconstruct the circumferential liquid film of vertical air-water annular flow and extract the characteristic parameter of the liquid film thickness based on the laser-induced fluorescence (LIF) and virtual stereo vision sensor. The virtual stereo vision sensor comprises a high-speed camera and two optical reflection sets, which can acquire the liquid film from two views simultaneously and reconstruct the multiple features of liquid film. The paper is organized as follows: Section 2 introduces the experimental flow loop and develops a virtual stereo vision sensor to achieve the cross-sectional views of liquid film.
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