Location:
Classroom 3, Sanderson
Date:
Thursday, March 27, 2014 - 13:00
Though there are many other forms of multiphase flow and a wide range of flow geometries, this seminar focuses on two-phase gas-liquid upwards flow in vertical tubes. Even with this restriction, the field is a vast one and is possible only to deal with a few of the highlights. The seminar begins with a definition of flow regimes (bubble flow, slug flow, churn flow, annular flow and wispy annular flow). The following main topics are then addressed:
- The bubble flow to slug flow transition, with particular emphasis on void waves.
- Slug flow behaviour and in particular the variation of shear stress in slug flow.
- The slug flow to churn flow transition and the nature of churn flow and the components of pressure gradient in this regime. .
- Annular flow and the calculation of critical heat flux.
- Heat transfer in annular flow and the significance of disturbance waves.
- A possible link between bubble nucleation and turbulence in disturbance waves.
Professor Hewitt has worked on a variety of subjects in the general field of chemical engineering but his speciality for several decades now has been in multiphase flow systems, with particular reference to channel flow and heat transfer. Multiphase flow consists of the flow of more than one phase (solid, gas or liquid) and is exemplified by the flow of steam-water mixtures in boiler tubes (two-phase flow) and by the flow of oil/water/natural gas mixtures (‘three phase flow’) in North Sea pipelines. Professor Hewitt has published many papers and books in this industrially important area and has lectured on the subject widely throughout the world. He has had a wide experience of industrial application through his founding of the Heat Transfer and Fluid Flow Service (HTFS) at Harwell and through extensive consultancy and contract work. Professor Hewitt’s contributions to the field have been recognised by his election to the Royal Society, the Royal Academy of Engineering and the US National Academy of Engineering in addition to international awards.
