Effects of wedge geometric parameters on flow characteristics of oblique detonation waves in a non-premixed mixture

Detonation propulsion systems exhibit significant potential due to their high thermal cycle efficiency and rapid combustion rates. However, previous research primarily focuses on the initiation and stability characteristics of oblique detonation waves (ODWs) and lacks systematic analysis of the influence of combustion chamber geometric parameters on the performance of oblique detonation engines (ODEs). This study employs Reynolds-Averaged Navier-Stokes (RANS) equations with chemical reactions to numerically investigate the effects of wedge length and angle on engine performance and aerodynamic characteristics in confined spaces. The results indicate that there are two locations with peak heat flux on the upper wall of the combustion chamber, namely the expansion corner and the reattachment point, while the overall heat flux on the lower wall is significantly higher, approximately twice that of the upper wall. Changes in wedge length and angle lead to variations in the ODW angle and post-wave heat release. The key influence of wedge length on wave system structure lies in the weakening effect of the expansion wave at the end of the wedge on the ODW, whereas the influence of wedge angle is primarily through changes in the wave angle and the resulting variations in the recirculation zone on the upper wall. Further analysis of thrust performance under different wedge lengths and angles reveals that the thrust augmentation initially increases and then decreases with increasing wedge length, while it continuously increases with increasing wedge angle. The analysis shows that the performance changes depend on the impact of drag and combustion gain induced by the wedge on the pressure thrust on the upper wall. The optimal wedge length is determined by the condition where the expansion wave at the end of the wedge no longer affects the ODW intensity and heat release, while the optimal wedge angle corresponds to the angle at which the detonation wave impacts the corner of the combustion chamber's upper wall.