Simultaneous high-speed schlieren and chemiluminescence imaging on the propagation characteristics of continuous rotating detonation wave in an optically accessible combustor

In this short letter, simultaneous high-speed schlieren and chemiluminescence imaging is demonstrated in a rounded-rectangle continuous rotating detonation combustor for the first time. Typical flowfield structures of the continuous rotating detonation (CRD), such as the fuel injection structure, fresh combustible mixture layer, detonation wave, and the downstream oblique shock wave, are clearly identified by the schlieren images. Integral of chemiluminescence intensity (ICI) of the simultaneous schlieren and chemiluminescence images fluctuates periodically, indicating the rotation motion of the shock wave and reaction zone, and the propagation frequency of CRD wave can be obtained by the fast Fourier transform on the ICI results. The induced shock wave and the front of the reaction zone are highly coincident in the simultaneous schlieren and chemiluminescence images. Furthermore, the frequencies of the local ICI in a monitor area at the same circumferential position of schlieren and chemiluminescence images well coincide with each other, which quantitatively verified that the non-premixed CRD wave is an interacted structure of induced shock wave coupled with the following reaction zone. Simultaneous high-speed schlieren and chemiluminescence imaging demonstrates great potential for characterizing detailed flowfield structures and propagation characteristics of CRD wave.