On the feasibility and performance of the ammonia/hydrogen/air rotating detonation engines

A series of numerical simulations were performed to investigate the feasibility and performance of the premixed ammonia/hydrogen/air rotating detonation engines. A 19 species and 80 reactions ammonia/hydrogen/air mechanism is adopted and validated for detonation simulations. The effects of injection total temperatures (T0) and ammonia/hydrogen equivalence ratios (φNH3 and φH2) are analyzed under a fixed global equivalence ratio of 1. The propagation map of rotating detonation waves is numerically outlined. The result indicates that a higher injection total temperature and a lower ammonia equivalence ratio are beneficial to the successful propagation of rotating detonation waves. The maximum φNH3 with successful propagation of rotating detonation waves reaches 0.6, achieved at T0 = 1000 K. High total temperatures and ammonia equivalence ratios can lead to lower detonation wave speeds. The detonation height is found to account for around 20%–36% of the engine axial length. The critical accommodated detonation cell number for successful propagation of rotating detonation waves is 5.9, below which the rotating detonation wave will have difficulty maintaining propagation. Mass-flow-averaged and area-averaged methods are adopted to evaluate the pressure gain performance of NH3/H2/air RDE. The results of the two methods both indicate that the total pressure gain is significantly affected by the injection total temperature but less affected by the equivalence ratio of NH3. In addition, it is found that NOx emission is dominated by NO. The NOx emission increases with increased injection total temperatures and ammonia equivalence ratios. Negligible NOx emission is produced in pure hydrogen-fueled RDE while it reaches the maximum (0.037) at φNH3 = 0.6 and T0 = 1000 K.