Understanding Changes in Aviation Emissions due to SAF with New Combustor Engine Technology

Project Number: 002
Category: Emissions

The research team with the guidance of emissions specialists at various original equipment manufacturers (OEMs) propose to make high priority ground-based field measurement campaigns of nvPM and combustion gas emissions from engines on a commercial widebody transport, a business jet aircraft, and a new technology combustor burning both conventional fuels and candidate sustainable aviation fuels (SAF).

The primary measurement projects are an advanced technology combustor and engine rig emission test, a single isle aircraft on-wing ground and in-flight contrail and emission measurement campaign, and a business jet on-wing ground and in-flight contrail and emission measurement campaign.  Each campaign is essential to fully understand aviation’s impact on the environment, potential benefits from emerging technologies, and the benefits of using alternative fuels. The advanced combustion technology rig measurements in combination with the measurements performed on an engine equipped with a matching combustor will enable the establishment of a nvPM transfer function for conventional fuels as well as 3 prime candidate SAFs and will enable development of powerful predictive capabilities. The in-flight measurement campaigns will not only look at the aircraft/engine efficiency combination but also the prediction and formation of contrails and the impacts and benefits of the use of low sulfur Jet A and SAF.  Ice crystal and humidity measurement taken during the campaign will help validate and improve two contrail prediction models (CoCIP and APCEMM). Lastly, the business jet on-wing and in-flight emissions and contrail measurements will be the first test for this aircraft and engine category.  The campaign will test with 100% HEFA SAF, a low sulfur Jet A, as well as conventional Jet A, confirm the operability of SAF in a business jet, and look at emissions and contrail formation up to flight level (FL) 550.

Project planning for these tests is highly dependent on the fuel and asset availability.  This ASCENT project allows for flexibility required to take advantage of assets and fuel availability opportunities as they become available and enables FAA, scientists, and industrial partners to coordinate effectively and deliver results in a timely manner.

This project is a continuation of ASCENT Project 2, 81, and 87.


The FAA, and the aviation industry are working to fully understand the impact of aviation on climate and air quality, including understanding the benefits of new combustor technology, use of low sulfur Jet A and SAF, and increase the use of sustainable aviation fuels (SAF) throughout the commercial and business aircraft fleets. The ground testing with 100% HEFA-SPK as well as SAF blends will investigate the effects of the fuel composition on emissions of different aircraft engine types and help quantify the effects of fuel composition on particulate emissions for these engines and thereby assist in estimating the positive environmental impact potential of adopting SAFs.  Additional key benefits including:

  • Characterizing the volatile and non-volatile particulate matter from engines not currently in the ICAO emissions databank for nvPM emissions.
  • Quantifying the effects of fuel composition on those emissions by making measurements using a range of SAFs and low sulfur fuels.
  • Comparing and validating the results obtained by each of the participants instruments against those of the other participants.
  • Comparing results with the data from prior campaigns to characterize how the particle emissions vary as engine combustor technology evolves.
  • Providing vital input for improving contrail modeling.
  • Providing the opportunity to acquire in situ monitoring of contrails and ambient atmosphere.

Last Updated 8/11/2023

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