Turbomachineries for Liquid Propulsion Rocket Engines

The rocket motor is one of the technological marvels enabling mankind to explore beyond the limits imposed by planetary gravity. Its role is to generate thrust in an intense, efficient and controlled manner.

This thrust propels space vehicles, enabling them to overcome gravity, inject themselves into orbit and maintain a stable trajectory compatible with mission objectives. The term "thruster" is often used to refer to equipment with a wide variety of functions, but with the same operating principle: high-speed ejection of an on-board fluid produces vehicle acceleration consistent with conservation of the system's total momentum.

These thrusters can be used for :

• control the orientation of a satellite, enabling it to point its instruments with precision;

• finalize orbiting or correct any drift;

• provide the launcher with the enormous thrust it needs for lift-off (Ariane 5 mass ∼ 800 t) and for its journey thousands of kilometers away from the earth's surface.

This article focuses on the latter option, characterized by power levels that are difficult to achieve without the help of auxiliary equipment, which makes up the so-called "rocket motor" package.

In aerospace practice, all equipment is subject to mass constraints. This is where the notion of compactness comes into play: a rocket motor's Thrust-to-Weight Ratio is an effective indicator of the quality of its design. The rocket motor turbopump plays an essential role in these considerations.