Abstract
A lot of studies on rotating detonation engines have been carried out due to the higher thermal efficiency. However, the number, rotating directions, and intensities of rotating detonation waves are changeful when the flow rate, equivalence ratio, inflow conditions, and engine schemes vary. The present experimental results showed that the combustion mode of a rotating detonation engine was influenced by the combustor scheme. The annular detonation channel had an outer diameter of 100 mm and an inner diameter of 80 mm. Air and hydrogen were injected into the combustor from 60 cylindrical orifices in a diameter of 2 mm and a circular channel with a width of 2 mm, respectively. When the air mass flow rate was increased by keeping hydrogen flow rate constant, the combustion mode varied. Deflagration and diffusive combustion, multiple counterrotating detonation waves, longitudinal pulsed detonation, and a single rotating detonation wave occurred. Both longitudinal pulsed detonation and a single rotating detonation wave occurred at different times in the same operation. They could change between each other, and the evolution direction depended on the air flow rate. The operations with a single rotating detonation wave occurred at equivalence ratios lower than 0.60, which was helpful for the engine cooling and infrared stealth. The generation mechanism of longitudinal pulsed detonation is developed.
Highlights
IntroductionDetonation engines theoretically have higher thermal efficiency than deflagration engines (i.e., conventional engines, such as rocket engines and air-breathing engines) since detonation has a lower entropy production than deflagration
Detonation engines theoretically have higher thermal efficiency than deflagration engines since detonation has a lower entropy production than deflagration
A stable single rotating detonation waves (RDWs) with a short exhaust plume occurred in the fuel-lean conditions with equivalence ratios lower than 0.6, operation conditions that are beneficial for an rotating detonation engine (RDE) to be applied as an airbreathing engine
Summary
Detonation engines theoretically have higher thermal efficiency than deflagration engines (i.e., conventional engines, such as rocket engines and air-breathing engines) since detonation has a lower entropy production than deflagration. The LPD frequency depended on the initial combustor pressure and equivalence ratio, with higher frequency observed with an increase in backpressure and equivalence ratio They concluded that LPD did not exist when there was no throat at the RDE exit. The tests simulated the effects of changeful air flow on the engines during the flight It showed that the combustion in an RDE tends to be affected by the combustor structure since the structure had a great effect on the mixing of the fuel and oxidant. A stable single RDW with a short exhaust plume occurred in the fuel-lean conditions with equivalence ratios lower than 0.6, operation conditions that are beneficial for an RDE to be applied as an airbreathing engine. Multiple corotating detonation waves never occurred in the range of air flow rates 72-740 g/s at a hydrogen flow rate 10 g/s
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