A summary of the research programme
The TRR 40 has been established in 2008 as a transregional research consortium of leading German Universities and DLR research centers in aeronautical and astronautical research with a focus on enabling technologies for future generations of space-transportation or launcher systems. Partnering up with ArianeGroup, TRR 40 has served to ensure Europe’s independent access to space. Only such a capability ensures political and economic independence of EU member states whose industries and security to a significant extent rely on usage and exploitation of the near-earth orbit, and whose scientific interests lie in Earth and planetary exploration. Future generations of space-transportation systems will offer a variety of launch capabilities and different levels of reusability. They will rely on chemical propulsion systems as primary engines, as this type of propulsion for the foreseeable future offers the best compromise between development and production cost, and efficiency. In particular, civil launches and human space flight rely on liquid-propellant technologies. Competitiveness with launcher producers from the U.S.A., Russia, and Asia requires further development of technologies on all sectors in terms of cost, efficiency, reliability, and environmental compatibility. The particularly high complexity and extreme thermal and mechanical loads of chemical propulsion engines call for intensive fundamental research as prerequisite for radical improvements and innovative technical solutions.
Critical, thermally and mechanically highly loaded components of space transportation systems with chemical propulsion engines can be differentiated according to their functionality and primary physical interactions. Throughout TRR 40 we differentiate the following categories: combustion chamber, nozzle, aft-body flows, and structure cooling. Aft-body flows and structure cooling are characterized by the interaction of thrust-chamber components. They are essential for the efficient and safe operation of space transportation systems. Combustion chamber and nozzle offer the highest potential for increasing overall efficiency. All components are coupled through strong interactions, however, such that design optimization or innovative design solutions of a single component cannot be successful without taking into account its interaction with all other components. Thus, it is not sensible to consider individual components separately from others. Such a procedure would imply gross negligence of important parameters and dependencies and would invalidate the results.
The technological challenges of the individual components and the need for an integrated treatment of the propulsion system lead naturally to the five Project Areas as substructure of the TRR 40:
• Project Area A: Structure Cooling,
• Project Area B: Aft-body flows,
• Project Area C: Combustion Chamber,
• Project Area D: Nozzle,
• Project Area K: Thrust Chamber.
Project Area K represents the application backbone jointly with the industrial TRR 40 partner ArianeGroup. The thrust chamber system consists of the combustion chamber (Project Area C) and the nozzle (Project Area D) as the main hardware components. Operational components of the thrust chamber are structure cooling (Project Area A) and aerodynamic integration into the aft body (Project Area B). Among Project Area K projects are those that define and operate simplified or generic representations of thrust-chamber hardware components. Moreover, a synergizing subproject has been contributed and fully funded by ArianeGroup that maintains the TRR 40 reference thrust chamber as virtual demonstrator. The reference thrust chamber has been defined in three versions of full-scale thrust-chambers, fully represented by the ArianeGroup design-simulation environment. It has served as virtual technology testbed where the impact of TRR 40 technological innovations on thrust chamber components have been tested virtually and qualified. Moreover, state-of-the-art research simulation methods, developed by TRR 40, have been used to identify weak links of the design simulation environment and to assess the gain in prediction accuracy offered by the incorporation of such modern simulation methods into the simulation environment. The nozzle and its interactions are subject of Project Area D. Such interactions are determined by the combustion chamber, which is subject of Project Area C. The effects of heat transfer on combustion chamber and nozzle operation and on cooling have been investigated in Project Area A. Exterior loads on the nozzle are the result of exhaust-plume interaction with the exterior flow, constituted the research focus of Project Area B.
Scientific core subject of all Project Areas is the multi-disciplinary investigation of nonlinearly coupled thermomechanical systems. Model development is based on experimental findings and validation by detailed numerical simulations. This is the backbone of all projects within each Project Area and for their interaction across Project Areas. Across its three funding periods, the TRR 40 has derived new technologies that have led to less costly, more reliable and more efficient thrust-chamber concepts, and improved design prediction tools.