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Description

Supersonic combustion ramjets, also known as scramjets, are a variation of jet engines designed to efficiently operate at speeds around Mach 5 and above. These engines produce great amounts of thrust, however the amount of turbulent energy involved in the combustion process could be inhibiting the engines fullest potential. It is already proven that hydrogen is the optimal fuel for scramjet combustion, with it producing the right amount of thrust while having minimal ignition requirements. However, hydrogens' high reactivity produces instability within the combustion chamber, seen as turbulent waves and excessive hot spots up to 3000 K. Using reduced order modeling, reactions were observed with varying air speeds from Mach 1 to 3. Simulations in Ansys Fluent showed that despite there not being drastic increases in temperature, vorticity and instability rose significantly with an increase in Mach number. Turbulence kinetic energy also increased as Mach number increased, however the paths and reactions stayed fairly the same with only a bit of expansion. As expected, the intensity of the turbulence kinetic energy is highest right at the injection point due to the immediate reaction between air and the liquid hydrogen.

Publication Date

4-1-2025

Keywords

scramjet, supersonic combustion, hydrogen fuel, turbulent kinetic energy, Mach number, combustion instability, vorticity, Ansys Fluent, reduced order modeling, CFD simulation, combustion chamber, fuel injection, high-temperature zones, flow dynamics, shock waves

Improving Stability of Scramjet Combustion via Hydrogen Fuel Injection

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