Realization of methane-air continuous rotating detonation wave.

Methane-air Continuous Rotating Detonation (CRD) has been firstly achieved in this paper in the hollow chamber with a Laval nozzle, and the diameter of the chamber is just 100 mm. The contraction ratio of the Laval nozzle is a key factor for the CRD realization. CRD can only be obtained when the contraction ratio is no less than 4, but its ER operating range decreases in the increase of contraction ratio from 4 to 10. For all the success cases, the average propagation frequency and velocity are in the ranges of 5.32–5.65 kHz and 1670.48–1774.10 m/s, respectively, and the velocity deficits are less than 10%. Based on the high-speed photography images, the approach of chemiluminescence intensity integral is proposed in this paper, and the propagation characteristics of the flame are analyzed quantitatively. The propagation velocities of the flame and shock wave are agreed well with each other, indicating that the typical feature of detonation wave, i.e., the coupling of the flame and the shock wave, is verified quantitatively. • Methane-air CRD is firstly achieved without additional oxygen and hydrogen. • Realization is in the small hollow chamber with the diameter of 100 mm. • The average velocity of success cases is in the range of 1670.48–1774.10 m/s. • Chemiluminescence intensity integral is proposed as a new image processing method. • The velocity coupling of flame and shock wave is verified quantitatively. [ABSTRACT FROM AUTHOR]