Based on the heritage of carbidic Ceramic Matrix Composites (CMC) applied for hot structures and thermal protection systems on re-entry vehicles, Astrium SI has developed alumina-fiber reinforced CMC systems (oxide ceramic) which do not require oxidation resistant coatings in atmospheric environment at high temperatures. As most launch vehicle configurations require in the vicinity of the rocket engine a thermal protection due to the impact of base heating their is a need to incorporate an adequate engine heat shield assembly. For the application on future RLV’s this engine heat shield has also to be designed for reusability.
Compared to the state-of-the-art systems the envisaged CMC heat shield concept provides high mass saving potential which improves significantly the position of the center of gravity of further space transportation systems.
Therefore Astrium SI has proposed a promising ceramic concept which is currently further developed within the frame of the national German program TETRA. After a general feasibility study performed during last year the detailed development has been started. First tasks were to establish a generic requirements specification and to carry out a trade-off for different design concepts.
As a first step the engine heat shield development aims to a verification of the major capabilities on a flight demonstrator. For that reason the HOPPER RLV concept currently under development has been selected as reference configuration.
Major challenges of the engine heat shield project will be the design and manufacturing of large 3-dimensional structures using oxide CMC and to provide a sealing system which prevents high temperature gas flows entering the heat shield inner compartment and allow on the other hand for sufficient venting capability during ascent and re-entry mission phases.
For the heat shield design it is essential to know besides other requirements (e.g. mechanical loads) especially the aerothermal environment in which such a heat shield shall be operated. For this reason first aerodynamic analyses have been performed to gather information about flow/temperature/pressure distribution in the vicinity of the heat shields.
This paper describes concept studies of an oxide ceramic based engine heat shield as well as the results of the analytical work performed so far.