This article is about a research developed at Universidad de los Andes on the aireation of high velocity flows as prevention against cavitation erosion. The research was a consequence of the results found in the physical model of the Río Guavio Hydorelectric Proyect near Santafé de Bogotá and was based in the study on a general model of a spillway with aeration system which did not represent a particular prototype. In the Guavio study one conclusion was obtained: In every aeration system there are three unknows which are the air discharge injected to the water flow (design object variable), the subpressure under the water jet and the jump lengh of that jet. In the research those three variables were studied using dimensional analysis and multivariable regresions in order to find a set of three equationes that allow the desing of this type of structures. The new equations are more general than those reported in technical literature.