ISSN Online: 2377-424X
International Heat Transfer Conference 12
Experimental investigation of vapor bubble growth
Аннотация
An experimental investigation of a vapour bubble growth is performed for water boiling inside a small cube shaped cavity under subatmopsheric pressures. Generation of an isolated bubble is achieved by concentrating heat flux on a small metallic area at the center of the horizontal surface. Bubble growth, recorded using a high speed camera (4500 frames/s), is observed in conditions very close to the ones considered in numerical simulation : axial symmetry, no slip on the heating surface and smooth and regular liquid-vapor interface. Image analysis is performed using a scheme specifically developed for this purpose. The bubble external contour is captured by an edge extracting technique then fitted by Bezier polynomials. The contact line between the wall and the liquid vapor interface is investigated and time evolution of the contact angle and of the bubble base are
presented. The velocity at any point of the bubble edge is computed using the optical flow PIV method. Bubble
growth mechanisms involved in the present investigation are qualitatively in good agreement with the ones
derived from numerical simulation and reported in the literature. This experiment and the associated data
analysis represent then a useful means of comparison. Temperature and velocity fields in the liquid surrounding
the bubble are determined using liquid crystal tracers and a 3-CCD color video camera. They reveal the adversity
to achieve a quiescent and thermally uniform bath during bubble growth experiments.