2015 IR&D Annual Report

Effect of Jet Fuel Properties on Soot Mass and Solid Particle Number Emissions from Aircraft Engines: Development of a Fuel Particulate Matter (PM) Index Concept, 03-R8497

Principal Investigators
Imad A. Khalek
Nigil Jeyashekar

Inclusive Dates: 10/01/14 – 10/01/15

Background — Jet engines will be subject to a new particle emissions regulation likely to start in 2022. Health effects of ultrafine particles emitted from gas turbine engines and the potential of black carbon effects on climate change are the major driver for the regulation. The regulation focuses on soot or black carbon mass and solid particle number emissions down to very small particles, 10 nanometer in diameter. Jet fuel properties are expected to have a strong impact on particle emissions from gas turbine engines. There is an industry need for a consistent fuel metric that can be used as a predictor for jet fuel particle forming potential in gas turbine combustion. This is important both on the national and international level due to the global nature of the aerospace industry.

Approach — The project was initiated to better understand the effect of fuel properties on particle emissions from gas turbine engines. The work was performed in our laboratory using a simulated gas turbine combustor and five different jet fuels with different aromatic contents. Particle measurement included total (solid + volatile) particle number and size, solid particle number and size, and soot mass. Combustor operation included simulated idle, takeoff, and cruise conditions. As a part of this investigation, we developed and used a singular jet fuel particle index (JFPI) as a means to differentiate fuels for their soot formation tendencies. The JFPI included more than 800 measured fuel species and combined both the physical and chemical characteristics of fuel properties.

Accomplishments — The work demonstrated that jet fuel properties have a drastic influence on the size, number, and mass of particles emitted from gas turbine engines. Most importantly, we were able to demonstrate that the JFPI developed in our work can be used as an excellent indicator of jet fuel soot forming tendency in gas turbine combustion. For example, good linear correlation (R2 ~0.93) was observed at cruise condition between solid particle number and soot mass and the JFPI. The JFPI can be used as an important indicator to differentiate jet fuel soot forming tendency worldwide. We plan to write a paper for the 2016 ASME Turbo Expo. We also plan to launch an industry consortium in 2016 to expand the development of the JFPI to more fuels and various combustion system designs.

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