School of Mechanical Engineering Seminar
Wednesday, December 20, 2021 at 14:00   
Wolfson Building of Mechanical Engineering, Room 206

Development of a validated simulative approach for the processes in CH4-O2 space engine combustion chambers

Andrej Sternin

Technical University of Munich

Andrej Sternin^{1, 2}, Daniel Martinez¹, Oskar Haidn¹, Yuval Dagan²

¹ Technical University of Munich (TUM), Boltzmannstr. 15, Garching b. München, oskar.haidn@tum.de, +49 89 289 16084

² Technion - Israel Institute of Technology, Haifa, 3200003, Israel

Assistant Professor, Faculty of Aerospace Enineering

The presented work provides valuable experience for setting up a CFD strategy for the very specific conditions inside rocket engine combustion chambers. This strategy involves the creation of experiments [1][2] for validation purposes, development of complementary chemical schemes [3], as well as the improvement of combustion and turbulence modelling [4]. The latter is supported by sophisticated DNS-Simulations.

This large-scale long-term effort origins in the beginning of the last decade and is continuing to this day. Its goal is to support the development of space propulsion systems using Methane as fuel. Even though the history of this effort, including experimental and numerical work is presented, the focus of the main author as well as the focus of the presentation lies on CFD methods. They cover strongly parametrised RANS approaches as well as high fidelity DNS Simulations of (non-) premixed flames.

For RANS simulations mainly ANSYS-Products are used. DNS simulations are conducted with the OpenFoam-based implicit “EBI-DNS”-Solver from the Karlsruhe Institute of Technology.

In the frame of the DFG-TRR-40 project significant progress could be achieved [5][6][7]. The laminar flamelet combustion model was enhanced to cover strong enthalpy gradients. Numerical stability and turbulent parameters and have been adjusted for different chamber designs, operating points and simulative approaches. The most recent work focuses of improving the consideration of two-way Turbulence-Chemistry-Interaction (TCI). The impact of the turbulence on the reaction rates is covered by correction models, like EDC, PaSR. However, they are based on generic assumptions and adjusted for conditions (e.g. MILD-Combustion), very different from those in rocket engines. Here, locally adaptive parameter adaption in combination with sensitivity analyses has been performed. The results are to be validated with corresponding DNS-Simulations.

The effect of flames producing turbulence has been less thoroughly explored [8]. This effect is assumed to be sufficiently relevant under rocket engine conditions. On the one hand, non-premixed flames are less likely to produce new turbulence than premixed flames. On the other hand the “extreme” thermo-chemical conditions in high thrust space engines decrease the chemical time scales, which again supports turbulence production. At the moment our team is working on the step to DNS of non-premixed flames. Their phenomena is significantly less explored, than of premixed flames, especially in terms of TCI.

Depending on the granted time for the presentation, the first author will elaborate on these issues

[1] Silvestri S., Celano M. P., Schlieben G., Knab O., & Haidn O. J. (2016). Experimental Investigation on Recess Variation of a Shear Coax Injector in a GOX-GCH4 Combustion Chamber. Space Propulsion Conference.

[2] Silvestri S., Riedmann H., Knab O., & Haidn O. J. (2015). Comparison of Single Element Rocket Combustion Chambers with Round and Square Cross Section. Proceedings of DFG TRR40 Summer Program, 311–325.

[3] Slavinskaya N. A., & Haidn O. J. (2011). Kinetic mechanism for low pressure oxygen / methane ignition and combustion. AIAA/ASME/SAE/ASEE 54th Joint Propulsion Conference & Exhibit. DOI: 10.1051/eucass/201304707

[4] Martinez D., Sternin A., et al, (2021)  Analysis of periodic synthetic turbulence generation and development for direct numerical simulations applications. Physics of fluids

[5] Roth, C., et al,  (2016). Numerical Investigation of Flow and Combustion in a Single-Element GCH4/GOX Rocket Combustor. Propulsion and Energy Forum, Salt Lake City

[6] Perakis N., Haidn O. J., Rahn D., Ehringhaus D., Zhang S., Daimon Y., Karl S., & Horchler T. (2018). Qualitative and quantitative comparison of RANS simulation results for a 7 element GOX/GCH4 rocket combustor. AIAA/ASME/SAE/ASEE 54^th Joint Propulsion Conference & Exhibit. DOI: 10.2514/6.2018-4556

[7] Sternin A., Ma H., Liu J., Haidn O. J., & Tajmar M. (2019). Turbulence and Combustion and Film Prediction in Rocket Application via Parameter Adjustment, Model Variation and Deep Learning Method. Proceedings of DFG TRR40 Summer Program, 119–137.

[8] Towery C. A. Z., Poludnenko A. Y., Urzay J., O’Brien J., Ihme M., & Hamlington P. E. (2016). Spectral kinetic energy transfer in turbulent premixed reacting flows. Physical Review E, 93(5), 1–11. DOI: 10.1103/PhysRevE.93.053115

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