OH imaging in a non-uniform, hydrogen-fueled scramjet engine

The hydroxyl radical, OH, acts as a convenient indicator of combustion within hypersonic engines. This paper presents results from OH imaging within a scramjet combustor in the T4 hypersonic shock tunnel. Three methods are presented, being time-integrated emission, time-resolved emission, and planar laser-induced fluorescence. All methods capture emission in ultraviolet wavelengths, around λ = 310 nm. The resulting 2D images are representative of OH density and hence combustion. These images show the dependence of combustion on the shock structure within the scramjet combustor