关键词: 引射喷管;第三流路辅助进气;进气门开度;次流状态;最小顺流压比

Abstract: In order to avoid overexpansion of the flow in the ejector nozzle under low pressure ratio， the flow characteristics in an integrated ejector nozzle with tertiary door are investigated. The effects of the secondary flow states， i.e.， reversed flow and downstream flow， on the ejector flow features are analyzed under the flight Mach number of 0 and the nozzle pressure ratio （NPR） of the primary flow of 2.1. And the minimum downstream pressure ratios at different opening angles of tertiary door have been obtained. The results show that when the secondary flow is in the reversed flow state， with the increasing of the opening angle of the tertiary door， the overexpansion degree of the mainstream gradually decreases. The mass flow rate of the tertiary flow increases， which arises the momentum transfer efficiency in the shear layer， leading to an ascending tendency of the thrust coefficient from 0.60 to 0.73. When the secondary flow is in the downstream flow state， the secondary mass flow rate descends and the overexpansion degree of the mainstream gradually increases with the opening angle of tertiary door. The increase in the mass flow rate of the tertiary flow lowers the momentum transfer efficiency in the shear layer， resulting in a decreasing thrust coefficient from 0.97 to 0.75. As the thrust coefficient in the downstream flow state is higher than that in the reversed flow state， a better thrust performance could be attained in the downstream flow state. Nevertheless， the secondary flow may be reversed under low flight Mach number， it is beneficial to increase the opening angle of tertiary door to improve the thrust performance in this state. Furthermore， as the angle of the tertiary door gradually increases， the minimum downstream pressure ratio of the secondary flow shows an increasing trend.

Key words: Ejector nozzle;Tertiary intake;Opening angle of tertiary door;State of secondary flow;Minimum downstream pressure ratio