Enhancing Scramjet Combustion: Leveraging Shockwave-Fuel Interactions for Improved Mixing

This research focuses on improving scramjet combustion efficiency by analysing how fuel interacts with shockwaves at various injection angles and different positions. Scramjet engines, which operate at hypersonic speeds, require efficient fuel-air mixing and stable combustion in extremely high-speed airflow conditions. Key challenges include managing turbulence, flame stability, and optimizing the mixing of fuel with air in the presence of shockwaves. Building on previous studies, we explore how altering the angle and position of fuel injection affects these processes. A numerical simulation was conducted on a scramjet combustor where hydrogen fuel is injected into supersonic airflows. The setup includes a wedge placed inside the combustion chamber, generating shockwaves that interact with the injected fuel. We analysed four different injection positions relative to the shockwave, each tested with three fuel injection angles: 90° (perpendicular to flow), +45° (with flow direction), and -45° (against flow direction). The main goal was to examine how these angles and positions influence fuel-air mixing, fuel-residence time (the duration fuel stays in the combustor), and overall combustion efficiency. Our results show that injecting fuel in the same direction as the airflow (+45°) promotes better fuel-air mixing and more stable combustion. This is because the fuel remains in the core of the high-speed flow, allowing it more time to mix with the air before combustion. On the other hand, injecting fuel against the airflow (-45°) generates higher turbulence, heat release, and increases the outlet temperature, which can boost energy output but poses challenges in managing thermal loads within the engine.