PhD opening at Eindhoven University of Technology

The effect of flow on boiling bubble detachment

The special feature that typifies a rifled tube is the special flow that is created in it: a swirling motion. We therefore focus on the effect of flow on detachment volume. We install a certain velocity field, and investigate its effect on the detachment of a boiling bubble. The research is mainly experimental.

In the experiments, a single bubble is introduced at the centre of a mock-up of a rifled tube wall. This tube-wall part is positioned in the centre of the test channel. An artificial cavity and a small heating element are in the centre of the tube-wall part. The bubble detachment volume is measured accurately for various conditions with a high-speed video camera

Design criteria for the volume of a detaching bubble are usually based on analytical expressions for the forces on the bubble. Recently we have gained progress in analytically predicting the so-called added mass, viscous drag and hydrodynamic forces due to a uniformly approaching flow. One of the advantages of the well-defined bubble-flow situation of the test fig is the fact that it enables the validation of this analytical model. To develop new design criteria, the force balance needs to be completed with an expression for the shear lift force that is quantified by the experiments.

More info:
Dr Cees van der Geld
Technische Universiteit Eindhoven
Faculty of Mechanical Engineering
Section Process Technology