Research into Multi-scale Examination of MultiPHase physIcs in flowS (MEMPHIS)

Posted by Abbas Hasan | June - 27 - 2017 | 0 Comment

A paper has been accepted and will be presented on 10th World Congress of Chemical Engineering, Barcelona, October 2017.

 

An experimental study of a falling liquid film in a vertical pipe

Abbas HASAN1, Barry AZZOPARDI1, Buddhika HEWAKANDAMBY1, Shara K. MOHAMMED1, Yousuf ALAUFI1

 1 Faculty of Engineering, University of Nottingham, University Park, NG72RD,UK

Abstract

The majority of the experimental and theoretical studies in literature on the falling liquid film focus on either small diameter pipes or flat plates. Almost, all these studies provide time series data of the film thickness at a single point on the pipe wall. In this paper, a unique Multiple Pin Film Sensor (MPFS, which comprises of 10 axial planes and 64 circumferential electrodes at each plane, i.e. 640 measurement points in total) was used in a large diameter pipe (127 mm). This sensor is capable of providing film thickness measurements around the circumference of the pipe with a spatial resolution of 6.2 mm. Further, it makes measurements at 10 planes normal to the pipe axis giving the axial evolution of the film along the pipe wall (the axial spatial resolution is 15.4 mm). 3D interfacial wave structures were reconstructed from the measured film thickness data. One of the advantages of using MPFS over the single point conductance measurement technique is the capability of capturing the detailed interfacial wave structures of the liquid film. Such detailed information is of interest to many modellers who need to validate their models and simulations. Parameters, such as film thicknesses, wave amplitudes, velocities, spacing and frequencies were extracted and analysed. Unlike smaller diameter pipes wher e the waves are characterised as coherent rings, the waves found in this study using larger pipe diameter were much localised. The mean film thicknesses are in good agreement with published models. The mean film thickness obtained from MPFS was also compared with the output of two other sensors, Ultrasound and conductance ring pairs. There is good agreement between the three methods, particularly when the fact that the ring pair technique provides a circumferentially averaged value. It was also found that the axial liquid velocity moves approximately with constant velocity and evolved with time.

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