The unstart phenomenon is investigated in the HyShot II model scramjet devised by the University of Queensland in Australia. Both the flight and DLR ground experimental measurements are used for validation. HyShot II was conceived with two combustors, one on each side but only one of the combustor was fueled, so that both cold and hot sides could be compared. The geometry is shown below.
Figure 1. Geometry and CFD flow visualization of the scramjet engine showing the wedge intake (front) and combustor with fuel off (top) and fuel on conditions (bottom), respectively. The contour plots show the square root of pressure.
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Figure 2. Contour visualization of the pressure (square root), temperature, mixture fraction and major product H<sub>2</sub>O mass fraction along two symmetry planes going through and between two injectors, along the bottom wall and at different cross-planes.
Figure 3. Pressure distribution in the combustion chamber along the bottom wall between two hydrogen injectors. The pressure is normalized by the combustor inflow pressure. The injector is located at x = 0 and the symbols correspond to the measurements of the DLR ground experiment.