Montreal Space Symposium

For the last 20 years, there has been a search for new propulsion devices based on detonation waves as the main process of energy conversion. Detonation waves are a specific type of chemical reaction process during which a reactant mixture is initially compressed by a strong shock wave to a very high pressure and temperature, thereby triggering high rates of chemical reaction and energy release. The presence of strong shock waves within the structure of detonation waves means that high levels of thrust can be achieved with a lower degree of initial compression. The high pressures and temperatures involved during the chemical reactions also makes it possible to achieve higher thermodynamic efficiency. Possible detonation wave based engines explored so far include the pulse detonation engine (PDE), the oblique detonation wave engine (ODWE) and, for the last 10 years, the rotating detonation engine (RDE). The RDE is of particular interest as it can produce thrust at zero vehicle speed, unlike the ODWE; it involves only a single ignition event unlike the required high frequency repetitive ignitions of PDEs; and exhibits a globally steady flow field, unlike the inherently pulsatile flow of PDEs, making traditional nozzle technologies adaptable to the RDE. Given that the detonation waves travel circumferentially in an RDE, the device is also more compact and thus potentially lighter than PDEs and conventional chemical rocket engines.
In this presentation, we outline the preliminary design procedure of an RDE and its fuel and oxidizer feed systems for a small-scale (roughly 10 cm diameter) rocket. There are multiple design considerations for the development of an RDE for rocket flight applications. Beyond minimizing the engine weight, mass flow rate and fuel type have a direct impact on the engine’s configuration as well as the material selection. In an RDE of a given size and fuel type, a minimum mass flow rate must be achieved to sustain a single, rotating detonation. This minimum mass flow rate is a function of the reactant mixture injection thermodynamic state, as well as its detonation properties. The reactant mixture must detonate easily and exhibit a small detonation cell size. Furthermore, the fuel and oxidizer are more easily stored in liquid form, which either places additional constraints on the rocket design or means using less detonable reactant mixtures. In the current work, we explore the design of H2/O2, C2H4/O2 and C2H4/N2O fueled engines. The effect of weight reduction on the engine heat loading is examined for short burn durations using one-dimensional models.