Andreas Gernoth

TMF test based validation of numerical methods for the analysis of heat-loaded walls

** †† ‡‡ , The creation of validation data for CFD, thermal, structural and life time analyses of actively cooled thermally loaded wall structures of rocket engines by means of ThermoMechanical Fatigue (TMF) - tests is discussed in this paper. During a TMF test, only a small section of the hot gas wall of the real engine (the so called TMF panel) is tested. For such a TMF panel, realistic cooling conditions similar to a full scale rocket engine are chosen. The 2d measurement of the thermal field of the heat loaded structure provides (together with the measurement of the temperature, pressure and mass flow rate of the coolant of the TMF panel) data for the combined validation of the CFD analysis of the coolant flow and the thermal analysis of the wall structure. The measurement of the deformation of the thermally loaded structure provides (together with the already determined temperature distribution and the above mentioned pressure measurements of the cooling channels) data for the validation of the structural analysis of the thermally loaded structure. Counting the number of laser loading cycles (laser on-off) until the TMF panel fails (by cracks appearing on the laser loaded side of the cooling channels) provides data for the validation of (either post processing or damage parameter based) life time analyses of thermally loaded structures.

TMF panel tests: close-to-reality simulation of thermo-mechanical fatigue processes in heat-loaded walls

The concept of a Thermo-Mechanical Fatigue (TMF) - test bench is discussed in this paper. Motivation for the TMF tests are two-fold: to assess the life expectation of structures being exposed to extreme thermo-mechanical loads first on subcomponent or panel level, and to serve as validation experiment for life-prediction models. In Europe, the concept of TMF-panel testing was first very successfully applied to rocket thrust chamber structures in the frame of the Ariane 5 Flight Recovery Programme in 2003 and 2004. These encouraging results have motivated the partners DLR Lampoldshausen and EADS Astrium to jointly investigate again the TMF-bench concept with special focus on meeting relevant requirements for future liquid propulsion needs. The following key elements of a TMF test bench are presented in the paper: the TMF heating device - a diode Laser, the panel housing, the fluid, measurement and control systems as well as the tentative design of a combustion chamber type TMF panel. Furthermore, numerical analyses of this tentative TMF panel – such as a CFD as well as a thermal and structural Finite Element analysis of the core part of the TMF panel during the Laser loading are shown.

Optical heating, thermography and deformation measurement of nozzle wall structures

Optical measurement possibilities for actively cooled thermally loaded wall structures of rocket engines by means of Thermo-Mechanical Fatigue (TMF) – tests aiming at the creation of validation data for CFD, thermal, structural and life time analyses are discussed in this paper. During a TMF test, only a small section of the hot gas wall of the real engine (the so called TMF panel) is tested. For such a TMF panel, realistic cooling conditions similar to a full scale rocket engine are chosen. The 2d measurement of the thermal field of the heat loaded structure provides (together with the measurement of the temperature, pressure and mass flow rate of the coolant of the TMF panel) data for the combined validation of the CFD analysis of the coolant flow and the thermal analysis of the wall structure. The measurement of the deformation of the thermally loaded structure provides (together with the already determined temperature distribution and the above mentioned pressure measurements of the cooling channels) data for the validation of the structural analysis of the thermally loaded structure. Counting the number of laser loading cycles (laser on-off) until the TMF panel fails (by cracks appearing on the laser loaded side of the cooling channels) provides data for the validation of (either post processing or damage parameter based) life time analyses of thermally loaded structures.

TMF tests: Optical heating, thermography and deformation measurement of combustion chamber wall structures

*† ‡ Optical measurement possibilities for actively cooled thermally loaded wall structures of rocket engines by means of Thermo-Mechanical Fatigue (TMF) tests - aiming at the creation of validation data for CFD, thermal, structural and life time analyses are discussed in this paper. During a TMF test, only a small section of the hot gas wall of the real engine (the so called TMF panel) is tested. For such a TMF panel, realistic cooling conditions similar to a full scale rocket engine are chosen. The 2d measurement of the thermal field of the heat loaded structure provides (together with the measurement of the temperature, pressure and mass flow rate of the coolant of the TMF panel) data for the combined validation of the CFD analysis of the coolant flow and the thermal analysis of the wall structure. The measurement of the deformation of the thermally loaded structure provides (together with the already determined temperature distribution and the above mentioned pressure measurements of the cooling channels) data for the validation of the structural analysis of the thermally loaded structure. Counting the number of laser loading cycles (laser on-off) until the TMF panel fails (by cracks appearing on the laser loaded side of the cooling channels) provides data for the validation of (either post processing or damage parameter based) life time analyses of thermally loaded structures.