Flowfield Analysis and Reconstruction of Ethylene–Air Continuous Rotating Detonation Wave

Abstract

The time difference calculation method, using the pressure peak rise time difference of high-frequency dynamic pressure signals to demonstrate the motion track of continuous rotating detonation wave (CRDW), is presented and verified. With the calculation method, the flowfield of CRDW has been reconstructed precisely. The angle of upstream oblique shock wave is defined for representing the influence of CRDW on the air inflow, which is impacted by the detonation combustion intensity and nozzle choking effect. The increase of combustor pressure makes the angle of upstream oblique shock wave decrease, indicating that the influence of detonation on air inflow strengthens. The angle of downstream oblique shock wave is mainly influenced by the contraction geometry of nozzle in the contraction ratio range of 2–10. The heights of CRDWs scatter around $60\pm 10$  mm ( ${\mathrm{C}}_2{\mathrm{H}}_4$ ), $40\pm 20$  mm ( ${\mathrm{H}}_2$ , single wave), and $20\pm 10$  mm ( ${\mathrm{H}}_2$ , two waves), respectively. The detonation wave height of single wave is higher than that of two waves in homo-rotating, and the height of ethylene–air CRDW is higher than that of hydrogen–air CRDW. This study will enrich the understanding and analysis method of CRDW flowfield structure.