Year: 2026
Type: article
Abstract: The propagation of ethylene–air detonation waves through alternating regions of unburned mixture and burned products is studied through high-resolution simulations. A significant jump in detonation wavespeed is observed when entering a preburned region due to the mismatch in acoustic impedance between unburned/preburned regions. However, wavespeeds in the unburned regions after exiting the preburned regions decrease below the Chapman–Jouguet speed due to lack of combustion within the preburned region and partial wave transmission. Ultimately, both an increase in the average wavespeed across the entire domain, and a decrease in the average wavespeed within the unburned regions is reported. The presence of preburned regions is also shown to modify the structure of the detonation, decreasing the number of cells while leading to oscillations in the induction length when entering and exiting the preburned regions. An additional, lower-pressure heat release mode is identified in the presence of preburned regions corresponding to the weakened detonation front and resulting unburned pockets of reactants. As the thickness of the preburned regions increases, the low pressure burning mode becomes dominant. Finally, thermodynamic work is shown to decrease as the thickness of preburned regions increases because lower wavespeeds lead to lower pressure ratios across the shock. Novelty and significance statement: This study analyzes ethylene–air detonation waves propagating through alternating unburned and preburned regions mimicking parasitic combustion like that present in rotating detonation engines (RDEs). For the first time, we identify an increase in overall wavespeed due to these preburned regions, as well as a decrease in local wavespeed in subsequent unburned regions. An additional burning mode is identified as the result of preburning and is linked to remaining pockets of unburned fuel. A novel thermodynamic work analysis is introduced to quantify the impact of lower wavespeeds due to preburning.
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,570
Funder: Air Force Research Laboratory
OpenAlex ID: W7203797243