CONDITIONS FOR THE RUPTURE OF A LUBRICATING FILM.
Abstract
An analysis is made to determine the shape of the film-vapor interface when a thin liquid film separates from a stationary surface and is swept away on an opposing moving surface. Situations in which variations of this phenomenon occur include cavitation in bearings, the spreading of thin films, and the movement of bubbles in narrow spaces. The results of the analysis show that for a fixed attachment height the flow carried in the separating film decreases with decreasing N = (3mu(U)/T) to the 1/3rd power. Stagnation points occur on the interface (with upstream recirculation) at a film height of 3F/U where F is the flow per unit film width and U is the plate velocity. As N decreases, the flow decreases; and the stagnation point moves down the interface toward the moving plate. A second stagnation point always occurs at the point of film attachment. A second important result is that film separation occurs in a distance of about one plate clearance. Because this transition distance is very small, the analysis is applicable to situations in which the plate velocity is not normal to the film edge, e.g. striated cavitation in bearings. The upstream transition distance is shown to be a few plate clearances.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1965
- Accession Number
- AD0629039
Entities
People
- H. G. Elrod Jr.
- J. C. Coyne