On the propagation mode evolution and detonability of diesel-fueled rotating detonation waves

Diesel-fueled rotating detonation combustors (RDCs) present a promising combustion technology for gas turbines widely used in marine and land-based power generation, benefiting from its high energy density and convenient storage. However, the propagation behavior, mode transition mechanisms, and detonability of diesel-fueled rotating detonation lack comprehensive investigations. Therefore, we developed a diesel-fueled experimental RDC system and conducted a series of tests by varying oxygen mass fraction and equivalence ratio. High-frequency pressure measurements and high-speed imaging were used to investigate the propagation modes of diesel-fueled rotating detonation waves (RDWs). Furthermore, theoretical calculations were performed to derive the critical initiation energy Ec. The influences of oxygen mass fraction and temperature on critical detonation energy were normalized, allowing for the prediction of the initiation temperature limits for RDW under pure air condition. The results characterized four distinct propagation modes: single-wave, two-wave co-rotating, dual-wave collision, and deflagration. Synchronized high-speed imaging and pressure measurements indicated that mode transitions were driven by local combustion. Theoretical analysis indicated that diesel possesses a longer induction zone length Δ and Ec than those of kerosene under identical conditions. The theoretical Ec values are inversely proportional to the experimentally measured RDW propagation frequencies for both fuels. By integrating the effects of oxygen mass fraction and temperature on Ec with experimental data, the initiation temperature limits for diesel–air rotating detonation is approximately 780 K. These findings illuminate the mode transition characteristics and detonability of diesel fuel, and provide a theoretical foundation for the application of diesel-fueled RDCs in land-based gas turbines.