The current design assumes a single unstart event per flight. Repeated cycling may lead to fatigue of the hatch mechanism. Furthermore, the plasma actuator's power draw (≈1 kW) may be prohibitive for small-scale scramjets.
| Parameter | Value | |--------------------------|--------------| | Freestream Mach number | 6.0 | | Inlet capture height | 0.15 m | | Combustor length | 0.8 m | | Equivalence ratio (nom.) | 0.9 | | Unblocker slot width | 2 mm | scramjet unblocker
A 2D Reynolds-Averaged Navier-Stokes (RANS) simulation with a shear stress transport (SST) turbulence model was conducted for a Mach 6 flight condition with a hydrogen-fueled scramjet. The current design assumes a single unstart event per flight
[1] Curran, E. T. (2001). Scramjet engines: the first forty years. Journal of Propulsion and Power , 17(6), 1138-1148. [2] Matsuo, K., et al. (2009). Unstart phenomena in scramjet inlets. Progress in Aerospace Sciences , 45(8), 285-310. [3] Do, H., et al. (2011). Plasma-assisted flame stabilization in a scramjet. Combustion and Flame , 158(4), 755-763. [4] Reed, A. J. (2024). Fast-acting bleed systems for hypersonic inlet control. AIAA Journal , 62(1), 112-125. (2001)
Scramjets are air-breathing engines essential for hypersonic flight and access-to-space systems. However, their operability is limited by the phenomenon of unstart , where the inlet shock system is disgorged forward, leading to a dramatic loss of thrust and potential vehicle damage. Traditional methods for unstart recovery involve fuel cutoff or variable-geometry inlets, which are slow and inefficient.
Scramjet, unstart, thermal choking, hypersonic propulsion, unblocker mechanism 1. Introduction