Detonation Structure in Ethylene/Air based Non-premixed Rotating Detonation Engine

摘要

Rotating Detonation Engines (RDEs) are getting more attention as a new pressure gain combustion system. In order to use RDEs to augment practical gas turbines, their stability and performance with more applicable hydrocarbon fuels need to be tested. In this context, ethylene/air systems are useful in analyzing RDE performance. Prior work has shown that ethylene/air systems exhibit suppressed wave propagation, with speeds that are nearly half the ideal wave speeds. The purpose of this study is to simulate realistic RDE configurations that have been experimentally studied to gain insight into this wave suppression. Detailed numerical simulations using a 21-species 38-steps chemistry model and a reduced 8-species 2-step model are conducted. When ethylene is diluted with hydrogen, the system exhibits two different wave modes, with a strong mode that is comparable to detonation propagation and a weak mode that behaves more like a deflagaration process. It is further shown that pure ethylene cases stay in the weak regime and contain only a weak pressure propagation that is aided by deflagaration along the wave path. As a result, the observed wave is not based on a conventional detonation structure.