Vapor bubble rise under a heated inclined plate

Data resulting from photographic studies of FC-87 vapor bubbles rising under a constant temperature plate are used to describe the growth and motion of the bubbles. Such bubbles are known to cause significant enhancement of heat transfer during their passage along the surface because of conduction through a thin liquid microlayer on which they slide, and because of extensive mixing in the wake behind the bubbles. Bubble velocity was found to be a function only of the bubble dimensions and surface inclination. The bubble width-to-length ratio was found to be an excellent indicator of the evolution in bubble shape from an initially spherical bubble through an elliptical shape to a large cap-shaped bubble. The data for heated FC-87 vapor bubbles compare well with Maxworthy’s observations of adiabatic air bubbles rising in water even though the vapor bubbles experienced rapid growth during their rise. Drag coefficients for the vapor bubbles were found to decrease with Reynolds number and approach plateau values at higher Reynolds numbers obtained from Maxworthy’s data.