Thrust Augmenting Ejectors, Part I

The solution of the equations representing the flow of a compressible fluid through an ejector has been shown to possess two distinctly different results after complete mixing. Part I of this study reported the analysis and described the performance of ejectors configured under the first solution where the flow after mixing is subsonic. The second solution to the ejector flow equations where the flow after mixing is supersonic provides a basis for selection of an optimal and a limiting ejector configuration for any given set of flight and injected gas characteristics. These special ejector configurations provide very high ideal thrust augmentations while translating from zero to supersonic velocities. Maps showing this ideal performance over large ranges of flight and injected gas characteristics are presented. Consideration is given to the influence of realistic, nonisentropic outlets as required for starting the supersonic flow (swallowing the starting shock wave) and for return of the supersonic mixed flow to ambient pressure. The data presented are limited to ejectors having a constant area mixing duct whose cross section is equal to 25 times that of the minimal area of the exhaust flow from the gas generator.