59443 - Influence of Alternative Fuels on the Liner Metal Temperatures in a V2500 Combustor 

Under the Flightpath 2050 program by the Advisory Council for Aviation Research and Innovation in Europe (ACARE), Europe’s aviation industry has committed to a reduction of CO₂ emissions per passenger kilometer by 75%. One approach proposed by ACARE to achieve this goal is the use of sustainable aviation fuels (SAF) in existing aero-engines. This option requires minimal modifications of the existing engine configurations, which makes it particularly attractive to airlines and engine manufacturers. One such SAF is HEFA-SPK (Hydro-Processed Esters and Fatty Acids - Synthetic Paraffinic Kerosene), which can be generated from the oil of Camelina sativa, a non-food oil crop.

In this paper, the authors investigate the influence of such a change in fuel composition on the hardware of a V2500 combustion chamber. Due to its large population, the V2500 aero-engine is of considerable interest for the MRO business and, thus, for the MTU Maintenance GmbH. According to Xue et al., HEFA generates, due to its lack of aromatics, close to zero soot particles during combustion [1]. Soot strongly interacts with the radiation emitted by the chemical reaction [2].The radiation in turn has, according to simulations by Konle et al., Saygin et al. and Da Soghe et al., a significant effect on the metal temperature of the combustion chamber walls [3-5]. This liner temperature is linked to the wear and tear that the combustor experiences during its operation [6].

In a previous paper, the authors already published a method to incorporate the complex cooling system of this combustion chamber into a numerical model. They also presented first results with respect to adiabatic wall temperatures [7]. This model is now extended to a full conjugate heat transfer (CHT) simulation, which is capable of accurately capturing the temperature distribution inside the combustor walls. Additionally, the used in-house solver, based on OpenFOAM, is capable of capturing the physics of radiation and soot formation. The applicability of the solver to commercial combustor designs was demonstrated in previous works [3, 8].

To facilitate a comparison between the traditional fuel Jet-A and the sustainable fuel HEFA, firstly CHT simulations with Jet-A are carried out and validated by a comparison of the liner temperatures with damaged hardware. Then, to mimic the absence of soot within the HEFA combustion, the soot generation is deactivated in the radiation model. Back-to-back comparisons of the numerical results reveal the potential differences in combustion temperature and wall liner temperatures expected for engine operation with HEFA.

[1] Xue, Hui, Singh, Sung: “Soot formation in non-premixed counterflow flames of conventional and alternative jet fuels.” In: Fuel 210, 2017

[2] Pal, Gupta, Modest, Haworth: “Comparison of accuracy and computational expense of radiation models in simulation on non-premixed turbulent jet flames.” In: Combustion and Flame, 2015

[3] Konle, de Guillebon, Cottier: “Multi-Physics Simulation of an Aero-Engine Combustor with OpenFOAM.” In: Proceedings of the 1^st Global Power and Propulsion Forum, 2017

[4] Saygin, Kocaman, Uslu: “Effect of Radiation on Gas Turbine Combustor Liner Temperature

with Conjugate Heat Transfer (CHT) Methodology.” In: AIAA Joint Propulsion Conference, 2016

[5] Da Soghe et al.: “Metal Temperature Prediction of a Dry Low NOx Class Flame Tube by Computational Fluid Dynamics Conjugate Heat Transfer Approach.” In: Journal of Engineering for Gas Turbines and Power, 2015

[6] Dai, Zhang, Ren, Liu, Wu, Ding, Lin: “Failure Mechanism of Thermal Barrier Coatings of an Ex-Service Aero-Engine Combustor.” In: Surface and Coating Technology, 2019

[7] Konle, de Guillebon, Schäflein: “Numerical Analysis of Dilution Hole Deterioration Impacting the Performance of a V2500 Combustor.” In: Proceedings of ASME Turbo Expo 2020

[8] Konle, de Guillebon, Beebe: “Multi-Physics Simulations with OpenFOAM in the Re-Design of a Commerical Combustor.” In: Proceedings of ASME Turbo Expo 2018