Experimental Investigation of Exhaust Jet Infrared Suppression for Supersonic Flow

The supersonic exhaust jet infrared suppression is one of the most important components of the supersonic aircraft performance.The projects of the second swirl flow and the combined petal lobe are provided in this paper.Their mechanism is that mixer ejector can cause large scale streamwise vortices into the downstream.It is these vortices that intake much more amount of atmosphere which also can stir up the main flow.The mixing zone between plume and external flow increases and the length of the central core zone of turbulent flow becomes shorter,so the infrared radiation of the jet exhaust decreases.The swirl ejector is used in the first project.The experimental results show that the higher is the speed of external swirl flow,the better is the performance of stir.The experimental results also show that when the angle of swirl flow is about 30 degrees,the performance is the best for the project.The combined petal lobe is used in the second project.The experimental results show that it is practicable to use combined petal lobe for the infrared suppression of supersonic flow.