Alternative Jet Fuel Reduces Aircraft Engine Emissions

  • Published
  • By Propulsion Directorate
  • AFRL/PR
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  AFRL researchers completed successful engine emissions tests to support the Department of Defense Assured Fuels Initiative, an effort geared towards securing domestic fuel sources to meet the military's energy needs.

To assess the performance of a manned Air Force aircraft running on alternative jet fuel, the research team measured the particulate and gaseous emissions of a TF33 PW-103 engine, comparing the results of burning conventional JP-8 fuel versus an alternative, 50/50 blend of JP-8 and Fischer-Tropsch synthetic fuel.

The tests showed that using the fuel blend produced significantly reduced particulate emissions for all engine conditions. Specifically, the researchers observed a ~20%-40% decrease in particle concentration and smoke number and a ~30%-60% reduction in particulate mass. Furthermore, the alternative fuel's effect on most gaseous combustion products was negligible, suggesting that it had no adverse impact on TF33 engine emissions.

To support ground testing of the F-T-derived fuel product, researchers working at Tinker Air Force Base, Oklahoma, used AFRL's Turbine Engine Research Transportable Emissions Lab to evaluate TF33 emissions over a wide range of engine operating conditions, from idle to maximum power.

Following completion of these ground tests, researchers flight-tested the alternative fuel aboard the B-52 bomber, evaluating it alongside conventional fuel (i.e., burning the fuel blend in two of the aircraft's TF33 engines and JP-8 in its remaining six TF33s). During a future flight test, the B-52 aircraft will burn the alternative fuel in all eight of its TF33 engines.

Developed in Germany during the early 1920s, the F-T process provides a method for producing alternative jet fuels from domestically available hydrocarbon products such as natural gas, coal, and shale.