Clarified the mechanism of cyclic interruption of reactant supplies and refilling on the valveless micro-PDE using high-speed shadowgraph technique.
Gas dynamics of shut-off and refilling processes in the inlets of a valveless micro PDE operating without the purging stage was studied using high-speed shadowgraph in this research. A transparent pulsed detonation engine was built for the high-speed visualization. Three inlet manifolds with different angles between fuel and oxidizer inlet channels were studied. It has been found that the back flow of burned gas into the inlet channels is crucial for the interruption of the reaction, and thereby stable pulsed detonation. Under lower supply pressures, small amount of unburned mixture was squeezed into the inlet channels that allowed the reaction to propagate further backwards into the inlets. Ethylene/oxygen supply pressure higher than 436/520 kPa, no reaction front was observed in the fuel and oxygen manifolds. Refilling process of the pulsed detonation cycle was initiated by the reverse of the flow direction at the inlet channel. Oxygen filled into the manifold ahead of ethylene due to higher supply pressure. Gases oscillation was observed in the manifold and the duration of gases oscillation was affect by the inlet channel angle and gas supply pressure. The burnt gas inside the manifolds was worked as a buffer zone to prevent the contact between fuel and oxidizer to prevent the pre-ignition.
1.Z.E. Chen and M.H. Wu, Gas Dynamics in the Inlet of a Valveless Micro Pulse Detonation Engine Operating without Purging State, The 25th National Conference on Combustion and Energy, Kaohsiung, Taiwan, April 24~25, 2015.
2.Z.E. Chen, C.H. Cheng and M.H. Wu, Influence of Pulsing Frequency and Inlet Design on the Initiation and Propagation of Pulsed Detonation Waves, AASRC Conference, Tainan, November 15, 2014.