Results are presented of an experimental program that investigated the use of a secondary air stream to control the amount of flow through a convergentdivergent nozzle. These static tests utilized high pressure, ambient temperature air that was injected at the throat of the nozzle through an annular slot.Multiple injection slot sizes and injection angles were tested. The introduction of secondary flow was made in an opposing direction to the primary flow and the resulting flow field caused the primary stream to react as though the physical throat size had been reduced.The percentage reduction in primary flow rate was generally about twice the injected flow rate. The most effective throttling was achiewed by injecting through the smallest slot in an orientation most nearly opposed to the approaching primary flow. Thrust edliciency, as measured by changes in nozzle thrust axfticient, was highest at high nozzle pressure ratios,NPR The static test results agreed with predictions obtained prior from PABSD, a fully viscous computational fluid dynamics program. Since use of such an injection system on gas turbine engine exhaust nozzles would be primarily at high NPRs, it was concluded that fluidic control holds promise for reducing nozzle weight and complexity on future systems. Svmbols

An experimental study of the axial and vectoring performance of two-dimensional (2-D) confined jet thrust vector control (CJTVC) nozzles was performed. The effects of adding secondary injection ports and changing exit height and secondary injection port location were studied on several 2-D CJTVC nozzles. The axial and vectoring performance results for these nozzles were measured over a range of pressure ratios. An analytical method for predicting flow separation was found to be applicable to these nozzles. Guidelines for designing 2-D CJTVC nozzles, that can be vectored uzing secondary injection, were established.-Recommendations for further study are made.

AIAA, Aerospace Sciences Meeting and Exhibit, 34th, Reno, NV, Jan. [15][16][17][18] 1996 The results of a computational study to investigate the impact of fluidic (secondary air) injection on the flow in an axisymmetric nozzle are presented. Details of the nozzle internal flow and the interaction between the nozzle flow and the fluidic injection are provided. The nozzle geometry consists of an axisymmetric convergent-divergent nozzle with a circumferential slot located at the nozzle throat. The effective throat area of the nozzle is controlled by injecting air through the slot. The effect of both primary and secondary total pressures on nozzle thrust ratio, mass flow ratio, internal static pressure, and exit-plane total pressure is discussed. Comparisons between computational results and experimental data are provided. Results show reasonable agreement between computed results and experimental data, considering the complexity of the flow. (Author) AbstractThe results of a computational study to investigate the impact of fluidic (secondary air) injection on the flow in an axisymmetric nozzle are presented. Details of the nozzle internal flow and the interaction between the nozzle flow and the fluidic injection are provided. The nozzle geometry consists of an axisymmetric, convergent-divergent nozzle with a circumferential slot located at the nozzle throat. The effective throat area of the nozzle is controlled by injecting air through the slot. The effect of both primary and secondary total pressures on nozzle thrust ratio, mass flow ratio, internal static pressure, and exit plane total pressure is discussed. Comparisons between computational results and experimental data are provided. Results show reasonable agreement between computed results and experimental data, considering the complexity of the flow.

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