Performance analysis of lobed nozzle ejectors for high altitude simulation of rocket engines

Abstract

Ejectors are used in high altitude testing of rocket engines to create vacuum for simulating the engine test in vacuum conditions. The performance of an ejector plays a vital role in creating vacuum at the exit of the engine nozzle and the nozzle design exit pressure at the time of ignition. Consequently, the performance of ejectors has to be improved to reduce the consumption of active fluid. In this investigation, the performance of an ejector has been improved by changing the exit shear plane of the nozzle. Conventionally, conical nozzles are used for creating the required momentum. Lobes of 4 no's, 6 no's and 8 numbers for an equivalent area ratio = 5.88 are used to increase the shear area. The influence of shear plane variation in the suction pressure is studied by a detailed CFD analysis.