Irene Ruiz Rodriguez

Irene Ruiz Rodriguez

Aerospace Engineering MEng

Injection in Liquid-Rocket Engines

Experimental Study on Liquid Jet Injection and Break-Up in Rocket Engines

Combustion in rocket engines is complex, demanding high reliability. Understanding fluid mechanics behind sheet breakup is vital to develop economical and environmentally-friendly propellants, pushing space boundaries. Current hazardous ones can result in catastrophic leaks like the sombre Challenger and Antares disasters. A step towards safer space exploration is developing gelled propellants, stored like solids. We studied atomisation (fluid breakup after impingement) of varying viscosity simulants using long, short and asymmetric like-on-like injectors under controlled pressures, discovering that laminar and turbulent profiles resulted in significant differences. For glycerol under laminar impingement, viscosity counteracted inertial forces developing an incombustible sheet whereas under turbulent, increased kinetic energy destabilised it. This finding means that under optimum pre-impingement, high viscosity fluids can atomise. Forgel, laminarity resulted in extensional flow as cross-linked molecules stretched. Under turbulent, bonds collapsed. These results are promising and Non-Newtonian fluids are postulated as strong future propellant candidates.