Performance of double-shroud ejector configuration with primary pressure ratios from 1.0 to 10

Hollister, Donald P., Greathouse, William K.

A brief investigation was made to determine the performance characteristics of a double-shroud cooling-air ejector configuration. Two convergent primary nozzles were used to simulate a specific manufactorer's iris-type variable-area nozzle in the open and closed positions. The investigation comprised four phases: (1) obtaining performance with no secondary or tertiary air flow (cooling-air passages blocked), (2) determining the tendency for backflow to occur in either cooling-air passage, (3) determining the sensitivity of flow in one passage to that in the other, and (4) obtaining pumping and thrust characteristics with secondary and tertiary air flow. The experimental results showed that the performance with the cooling-air passages blocked was typical of that for single ejectors having diameter and spacing ratios similar to those used in this investigation. There was a tendency for backflow to occur, but the magnitude of such flow was relatively small. The weight flow of each ejector was shown to be essentially independent of the other, and the closed primary-nozzle configuration was found to be generally capable of pumping more cooling air than the open primary-nozzle configuration. Gains in gross thrust were observed for both configurations, with losses occurring only at low secondary and tertiary pressure ratios.

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