Numerical study on the internal/external flow and thrust-drag characteristics of oblique detonation engine-based aircraft

The oblique detonation engine (ODE)-based aircraft employs the fast oblique detonation wave (ODW) combustion for airbreathing propulsion, delivering significant technical advantages in structure and efficiency under hypersonic flight conditions. However, achieving overall optimization by harmoniously integrating the ODE internal flows with the aircraft external flows remains a crucial yet unexplored aspect. Utilizing a multi-species reactive Reynolds-Averaged Navier-Stokes (RANS) model along with a detailed hydrogen-air combustion mechanism, an integrated airframe-propulsion ODE aircraft model is developed to investigate the internal/ external flow and thrust-drag characteristics of an ODE aircraft operating at a flight Mach number of 10. Simulation results demonstrate the two key aerodynamic and geometric design parameters, i.e., inlet exit Mach numbers Ma1 and combustor wedge angles 01, exhibit inverted U-shaped curve effects on ODE specific impulse Isp. The optimal configurations with Ma1 = 5 and 01 = 20 degrees are identified as the most effective balance for ODE performance, achieving the maximum Isp of about 1200s. The underlying mechanisms are elucidated from the viewpoints of variations in both combustion efficiency and total pressure. Furthermore, a slightly different inlet exit Mach number of Ma1 = 5.5 is found to achieve the maximum flight efficiency by reducing the flight drag, indicting the thrust-drag trade-off in ODE aircraft optimal design. This study provides a comprehensive understanding of the significance of balancing propulsion and aerodynamic performance for ODE aircraft to achieve superior overall performance, which holds the key to future engineering applications.