Ejector Thrust Augmentation

The mechanism of stationary or static ejector thrust augmentation was investigated. The assumptions includes that the primary and secondary fluids and their mixtures have constant density, the primary and secondary flows are isentropic upstream of the inlet station and the static pressure is constant across the inlet station. The additional thrust created by the exhaust diffuser is entirely due to the reduced static pressure exerted on the entrance bellmouth caused by the increased secondary flow mass flow and velocity. The thrust augmentation increased as the ejector length and diffuser area ratio increased. Thrust augmentation was primarily the result of the spreading of the energy resident in the primary flow to the secondary flow. The pulse detonation engine (PDE) fill-fraction behavior results from a related thrust augmentation phenomenon that is the highly efficient transfer of the kinetic energy of the detonated fuel-air reactants to the axially adjacent nonreacting or inert material within the confines of the same tube.