Experimental Study on Effects of Shock Wave Impingement on Supersonic Combustion

An experimental study has been conducted using reflected type of shock tunnel to investigate the effect of shock wave impingement on supersonic combustion. In the experiment, air is compressed by reflected shock wave up to total temperature of 2800 K and total pressure of 0.35 MPa. Shock heated air is used as a reservoir gas of supersonic nozzle. Hydrogen gas is injected transversely through 2mm-diameter circular sonic nozzle into free stream of Mach 2. Flow duration is around 300 microseconds. The effects of shock wave impingement on the combustion has been studied by generating three different shock waves using ramp which is located on the opposite side of the supersonic nozzle wall. The wedge angles of the ramp of 5°, 10° and 15° are selected. Schlieren method is used to visualize flow pattern and shock structures and the UV-CCD camera is used to observe region of combustion because the camera could catch the self luminescence of OH radicals which is produced by combustion. The combination of Schlieren images and UV images shows the shock structure in the flow field and its effect to the supersonic combustion. The shock wave impingement enhances the combustion and shock induced separated region, which is observed at stronger shock impingement, could work as flame-holder.