Session: 04-09 Combustion Experiments
Paper Number: 128796
128796 - Evaluation of Current and Future Aviation Fuels at High-Pressure RQL-Type Combustor Conditions
De-carbonizing the aviation sector is one of the biggest challenges in order to minimize climate change effects associated with the emission of carbon dioxide. Sustainable aviation fuels (SAF) will play a major role in this context especially for long-distance flights where hydrogen or all-electric propulsion systems do currently not present a feasible alternative. In addition, aromatic-free aviation fuels offer a promising solution to lower soot emissions of aeroengines. Today, limited experience of SAF combustion under aeroengine-typical operation conditions is existing. The test results described in this paper contribute to filling this gap.
Replacing conventional Jet A-1 fuel by SAF poses several challenges with respect to combustion. Two principle development strategies can be followed. The first, short- to mid-term one, is the development of SAF that reproduce closely the combustion characteristics of Jet A-1 to facilitate the use of existing combustor hardware. The second, mid- to long-term strategy is the co-development of SAF in combination with new combustion systems. The latter approach is more promising because of a higher emission (NOx, CO, soot) saving potential.
As a first step following route one, five fuels samples (Jet A-1 as reference fuel 2 blends and two neat synthesized paraffinic kerosenes from hydro-processed esters and fatty acids (HEFA-SPK)) supplied by Neste were tested in an optically accessible high-pressure rich-quench-lean (RQL)-type combustor at typical aeroengine conditions. This paper will report on optical diagnostics results (OH*chemiluminescence, Mie scattering) as well as on exhaust gas and particle sampling measurements to delineate the fuel effects on spray, flame and emission characteristics. Measurements were performed at pressures up to 10 bar, air preheating temperatures up to 773 K and at primary zone equivalence ratios in the range of 0.71 – 1.43, leading to a maximal thermal power of about 1.1 MW.
Mie scattering results showed that the liquid fuel distribution and fuel placement was sensitive to the properties of the five fuels. By contrast, all fuels resulted in very similar flame position and shape as observed by OH*-chemiluminescence measurements. As a consequence, NOx and CO emissions of the tested fuels differed only moderately. Particulate matter measurements at the fuel richest operating condition showed a clear ranking of the five fuels with the lowest particle emissions evident for the HEFA-SPK samples. Moreover, the particle volume concentration at the fuel richest condition followed the expected trend with fuel H-content.
Keywords: Sustainable aviation fuels (SAF), combustion characteristics, high-pressure, optical access, RQL-type combustor
Presenting Author: Peter Griebel German Aerospace Center (DLR)
Presenting Author Biography: Diploma Degree in Mechanical Engineering from Technical University of Karlsruhe (Germany)
Doctoral Degree in Mechanical Engineering from University of Bochum (Germany)
Senior Scientist, working for more than 20 years in the field of high-pressure low-emission combustion
Authors:
Peter Griebel German Aerospace Center (DLR)Fabian Hampp University of Stuttgart
Rainer Lückerath German Aerospace Center (DLR)
Oliver Lammel German Aerospace Center (DLR)
Tobias Grein German Aerospace Center (DLR)
Reetu Sallinen Neste Corporation, Technology Center
Jesse Vilja Neste Corporation, Technology Center
Kati Sandberg Neste Corporation, Technology Center
Evaluation of Current and Future Aviation Fuels at High-Pressure RQL-Type Combustor Conditions
Paper Type
Technical Paper Publication