Paola Breda M.Sc.

Paola Breda M.Sc.
LRT 10 - Institut für Thermodynamik
Gebäude 33/400, Zimmer 3453
+49 89 6004 2126
paola.breda@unibw.de

Paola Breda M.Sc.

Motivation

The main and the upper stage of liquid rocket engines (LRE) mainly rely on the well-established technologies developed for the cryogenic LOX/LH2 propellants. Such technology has been consolidated in the past 60 years, but it presents several disadvantages. The mean reason is that a larger volume for the fuel tank and pumps is required within the booster compared to a hydrocarbon-based engine. The aerospace community has increased the effort of investigating new engine technologies based on hydrocarbon fuels, with the re-usability being the driving factor. The focus has shifted from kerosene to methane, in particular. This is because methane properties are more reproducible than other oil-based hydrocarbons, and it can made widely available. Favorable cooling properties also make CH4 attractive for regenerative cooling systems. However, LOX/CH4 cryogenic stages have not flown yet, showing how a lack of knowledge in the field of high pressure combustion involving hydrocarbons is still present.
Recent efforts were initiated in order to provide the academic community suitable experimental data (i.e. within the DFG project SFB40), in order to calibrate the combustion models accordingly. Nonetheless, the accuracy of a combustion model is often limited by the available computational resources, especially if detailed simulations of turbulent reactive flows are attempted. The stiffness of the chemical system is increased for carbon-chemistry under high-pressure conditions. Not only because the number of reactions and species involved is increasing with the complexity of the chemical mechanism, but also because the chemistry time scales involved span a broader range. The computational bottleneck deriving from the increased stiffness of the chemical system must be therefore overcome, in order for the CFD simulation of turbulent reactive flows to be attractive for industry applications.
The purpose of this PhD research is investigating suitable reduced chemistry models for methane combustion, not only capable to predict the flow and flame structure under atmospheric conditions, but also in a rocket-like environment. The combustion models for such applications are mainly focused on non-premixed flame configurations. Moreover, the reduction models should also lead to a reliable prediction of the wall heat fluxes for rocket combustion chambers.

 

Field of research

All implementations listed hereby are interfaced to the end software used for the CFD simulations (OpenFOAM v. 4.1 and 6):

- Routine optimization for the creation of flamelets, including heat losses.  The integration of enthalpy losses is required in rocket combustion chambers,  due to the interaction of the flame with the cooled chamber walls:

  • Breda P., Pfitzner M., "Tabulated chemistry IDDES for thermal loads prediction in GCH4/GO2 combustion chambers", accepted for publication Journal of Propulsion and Power, Aug. 2020

  • Breda P., Pfitzner M. , Perakis N., Haidn O.: "Generation of non-adiabatic flamelet manifolds: comparison of two approaches applied on a single-element GCH4/GO2 combustion chamber", 8th European Conference for Aeronautics and Aerospace Sciences, Madrid, 2019, https://doi.org/10.13009/EUCASS2019-121
  • Breda P., Zips J., Pfitzner M.: "A Non-Adiabatic Flamelet Approach for Non-Premixed O2-CH4 Combustion". Proceedings of the 3rd World Congress on Momentum, Heat and Mass Transfer, Budapest, 2018, https://doi.org/10.11159/csp18.109
  • Breda P., Zips J., Pfitzner M.: "A Flame-Wall Interaction Study of Laminar Wall-Parallel Diffusion Flames Simulated with a Non-Adiabatic Flamelet Approach". Work-in-Progress Poster, 37th International Symposium on Combustion, Dublin, 2018
  • Zips J., Traxinger C., Breda P., Pfitzner M., "Assessment of Presumed/Transported Probability Density Function Methods for Rocket Combustion Simulations", Journal of Propulsion and Power, 2019, https://doi.org/10.2514/1.B37331
  • Hansinger M., Breda P., Zips, J., Traxinger C., Pfitzner M. : "Hybrid LES/RANS simulation of a GOX/GCH4 7-element rocket combustor using a non-adiabatic flamelet method".  SFB/TRR40 Summer Program, 2017

 

- Reducing the memory footprint required by densely discretized  chemistry tables by means of artificial neural networks. CPU-based neural network deployment:

  • Breda P., Trautner E., Klein M., Hansinger M., Pfitzner M.: "CPU-based Deployment of Artificial Neural Networks for LES of Reacting Flows in OpenFOAM". Accepted for presentation at 13th International ERCOFTAC Symposium (May 2021)

 

- Validation of new skeletal mechanisms for high pressure CH4/O2 combustion, targeted to rocket engine applications:

  • Saccone G., Natale P., Battista F., Breda P., Pfitzner M., "Methane/Oxygen Combustion Kinetic Scheme Optimization for Liquid Rocket Engine CFD Applications", Proceedings of the 4th World Congress on Momentum, Heat and Mass Transfer, Rome, 2019, https://doi.org/10.11159/csp19.105

 

- Validation of chemistry reduction models derived from the separation of the slow chemistry time scales from the fast ones (ILDM, TGLDM), including reaction-diffusion manifolds (REDIM). The turbulence-chemistry interaction of the LES sub-grid scale is modeled by means of  the Eulerian Stochastic Fields approach. Primary investigations are conducted on the Sandia flames D-E-F:

  • Breda P., Yu C., Maas U., Pfitzner M., "Validation of an Eulerian Stochastic Fields solver coupled with reaction-diffusion manifolds on LES of methane/air non-premixed flames", submitted to Flow, Turbulence and Combustion, March 2020
  • Breda P., Hansinger M., Pfitzner M., "Chemistry computation without a sub-grid PDF model in LES of turbulent non-premixed flames showing moderate local extinction", accepted for publication at Proceedings of the Combustion Institute, June 2020
  • Breda P., Hansinger M., Pfitzner M., "Low dimensional chemistry manifolds applied to premixed methane/air flames under atmospheric conditions", 9th European Combustion Meeting, Lisbon, 2019
  • Yu C., Breda P., Pfitzner M., Maas U., "Coupling of mixing models with manifold based simplified chemistry in PDF modeling of turbulent reacting flows", accepted for publication at Proceedings of the Combustion Institute, June 2020

 

- CFD investigation of the autoignition delay and the wall heat fluxes for a methane/hot air partially premixed flame configuration. The investigation is based on the experimental set-up of Dalshad.

  • Breda P., Dalshad R., Pfitzner M. : "Research on Reacting Cooling Films of GH2/GCH4 and Numerical Validation". Work-in-Progress Poster, 2nd International Workshop on Near-Wall Reactive Flows, Darmstadt, 2017

 

Teaching assistant

Winter Semesters 2018 and 2019: Fundamentals of heat transfer (in German)