Numerical investigation of nozzle flow separation control by injecting secondary jet from nozzle exit

The subscale nozzle model of a liquid rocket engine was researched. The corresponding flow field configurations were analyzed. The influence of main parameters of the secondary jet injector on control effectiveness was analyzed, including the injection angle, the area ratio and the total temperature of its working fluid. The results indicate that, when the secondary jet injector is adopted, the nozzle inlet total pressure which can make the nozzle reach full flow decreases 37.8%; as the injection angle increases from 0° to 25°, the nozzle flow separation location moves about 0.01 m towards the nozzle throat, and the control effectiveness of the device decreases significantly; as the total temperature of the injector's working fluid increases from 300 K to 1500 K, the nozzle flow separation location moves about 0.005 m towards the nozzle exit, and the control effectiveness of the device increases slightly. The area ratio has no effect on flow separation location when no flow separation occurs in the secondary jet injector, otherwise, the control effectiveness of the device will decrease.