A study of factors affecting thrust augmentation

Abstract

The purpose of thrust augmentation is to transfer the kinetic energy leaving a jet to a larger mass of air by providing some material boundary upon which this larger mass can react. The additional thrust force is derived by the differences in fluid pressures on the surfaces of the augmentor. If a negative static pressure exists on the inner surface of a convergent shape by virtue of an increase if velocity from a total pressure common to both surfaces, the thrust comes from the difference between the internal and external integrated pressures. In general, a jet directed into an augmentor mixes with and accelerates a larger quantity of low velocity secondary air. The discharge from the ejector will be a large mass of air with a lower velocity than that of the primary jet, and at some static pressure higher than that at the throat of the augmentor.