Flow and acoustic characteristics of convergent-divergent nozzle with and without wedges

Abstract

The advancements in flight have increased over the years to achieve and provide comfortable flights to passengers. In addition to shorter travel time, passengers expect good comfort and an eco-friendly environment with no noise around them. Most of the present turbofan engines are producing much noise due to the supersonic jets created at the nozzle. By increasing the mixing rate at the exit, it is possible to reduce the noise and increase the performance. The enhanced flow mixing can be achieved by using many methods such as active and passive control methods including co-flow jets and tabs. Here in this research, the selected method to provide the controlled jet was using wedges. The significance of using this method is its mixing efficiency by following the principle of entrainment of atmospheric air into the exit jet. The wedges used here act as a vortex generator. These produced vortices weaken the shocks and the shear layer thus the potential core length is reduced. The CFD analysis and experimental analysis were also done and the results were compared. The experimental analysis was carried out without and with a wedge nozzle. In experimental analysis 2 bar and 4.74, bar gauge pressure was used and for both cases and the Mach Number was 1.8. The high-speed jet facility schlieren flow visualization and acoustic analysis were carried out. In CFD analysis flow characteristics of 2 bar gauge pressure such as contours and graphs were obtained for both with and without wedge nozzle. From the results, it is clear that the second shock-cell length was reduced with the use of wedges.