Oliver Knab

LOX-Hydrocarbon Preparatory Thrust Chamber Technology Activities in Germany

Recent European interest in LOX/hydrocarbon propulsion systems focuses on LOX/kerosene versus LOX/methane propellants for liquid booster stages. For the preparation of a fair technical trade-off among the two propellant combinations, EADS-ST and DLR have started complementary activities addressing critical areas for the related thrust chamber development. These activities are closely coordinated, and are targeting on fundamentals such as the characterization of the propellant fluid properties, the propellant cooling characteristics, material characteristics, and ignition studies. Besides these fundamental research activities, further technology activities focusing on future application towards open and closed cycle engines have been started. This includes experimental verification of injector head designs, but also the enhancement of design tools to predict the hot gas side and coolant side heat transfer at relevant operational conditions. The technology activities finally focus on staged combustion battleship demonstrators for the coupled thrust chamber / preburner system, allowing for a fair technical trade-off between both hydrocarbon fuels.

Modeling of Rocket Combustion Devices

The numerical simulation of the hot-gas side within combustion devices is one important element during the development of todays rocket engines. This paper presents the Astrium hot-gas simulation tool, namely the in-house axisymmetric spray combustion code RocflamII, and shows its validation to experimental subscale data. Furthermore, the application of Rocflam-II to different Astrium rocket combustion devices is introduced, including large H2/O2 thrust chambers, an MMH/NTO apogee engine as well as a gas generator and a hybrid combustor. Whenever possible, the comparison to experimental data is given, proving a good agreement between simulation and test for wall heat flux and combustion efficiency. Thus, the suitability of Rocflam-II as a versatile design tool is confirmed. Furthermore, a commercial 3D CFD solver is used to get an insight into the phenomena not resolvable by an axisymmetric code. The results are promising, but need to be further improved.

Experimental and Numerical Film Cooling Investigations in a GOX/ Kerosene Rocket Combustion Chamber

Detailed knowledge on heat transfer is crucial for the design of reliable and efficient rocket engines. Due to high heat loads and chemical attack of the combustion chamber walls, film cooling is often applied supplementary for high pressure regenerative cooled combustion chambers or as a primary cooling technique for low pressure thrusters. Nevertheless, dominating processes determining the film effectiveness under conditions typical for rocket combustors are still not completely understood. The LFA operates a rocket combustion test facility which allows investigations on heat transfer at relevant combustion pressures and temperatures. In the context of a national research program SFB TRR 40 the LFA conducts experiments on film cooling, while Airbus Defence & Space carries out associated numerical investigations. In this paper results from film cooling experiments with kerosene film in a water cooled GOX/ kerosene rocket combustion chamber are presented. The tests have been performed at two different combustion pressures and with two different nozzle diameters to study the influence of the Mach number. In the numerical investigations, one major issue has been the modeling of kerosene films in suband transcritical state. For the modeling Airbus Defence & Space’s in-house code Rocflam-II has been applied. The main goal of Rocflam-II is to provide a tool package for the simulation of a wide range of rocket combustion devices, validated against experimental data. This includes the modeling of injection, atomization, mixing, combustion, wall heat transfer, film cooling as well as additional water cooling simulated by 1D or 3D conjugate heat transfer.