Mixing characteristics of vent slot mixer in supersonic flow

Non-reacting experiments were performed to show the mixing characteristics of the vent slot mixer by the injector location in Mach 2 supersonic flow. As the injectant such as hydrogen, helium, and air was injected into the supersonic main flow, flow structures were visualized by schlieren photography and stereoscopic particle image velocimetry. Pressure measurement and gas sampling were conducted in order to compare with their flowfield visualization. The mixing performance is highly sensitive to the injection position of the vent slot mixer. While the injection occurs under the vent slot mixer, the remnant injectant is evenly distributed toward the spanwise direction. In the meantime, the injection behind the vent slot mixer generates the jet plume containing a counter-rotating vortex pair which mainly affects the velocity field and turbulent motion around the jet plume. In the case of the vent slot mixer, because the jet plume is combined with the nearby shear layer, the injectant in the jet plume can be supplied into the nearby shear layer.