With the rapid advancement of space technologies over the past two decades, the number of commercial and private rocket launches and artificial Earth satellites has grown exponentially. Liquid- and solid-propellant rocket engines are most commonly used for these missions. Liquid-propellant rocket engines are characterized by high complexity and cost, whereas solid-propellant engines are technologically simpler and cheaper but have several major drawbacks – their thrust level and burn duration cannot be controlled. Hybrid rocket engines address these drawbacks by combining the advantages of both technologies: a solid fuel grain is used, which simultaneously acts as an uncooled combustion chamber liner, while the burning rate is controlled by adjusting the flow rate of the gaseous oxidizer. Owing to their lower system complexity, hybrid engines are considered safer and are employed in some suborbital (tourism) and sounding (scientific) rockets, as well as in emerging defense system concepts including UAVs. The main challenge in achieving real-time efficient thrust control for hybrid rocket engines is the optimization of the nozzle geometry. The rocket nozzle converts the thermal energy of high-pressure, high-temperature gases into kinetic energy, thereby maximising the exhaust velocity and the produced thrust. When the engine thrust is varied, the exhaust flow parameters also change, and consequently the optimal nozzle geometry must vary accordingly. With a fixed-geometry nozzle, the useful payload mass and achievable range are reduced, which makes it necessary to develop a methodology for determining the optimal nozzle shape for different engine thrust regimes. In this project, the collaborating partners will carry out experimental investigations and numerical modelling studies to optimise hybrid rocket nozzles, increase their specific impulse and thereby improve overall engine efficiency.
Project funding:
KTU fund for internal investment
Period of project implementation: 2026-04-01 - 2026-12-31
Project partners: Lithuanian Energy Institute
