Browse Topic: Aviation fuels

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In-Flight Evaluation of Sustainable Hydrocarbon Fuels in Compression Ignition Aircraft Engines2025-01-0533To be published on 11/25/2025
With global air traffic projected to increase significantly in the coming decades, reducing the associated climate impact requires scalable solutions. While alternative propulsion technologies such as electric and hybrid-electric systems might offer long-term potential, their current applicability remains limited due to low energy density, limited range and scalability, and system complexity. Consequently, thermodynamic propulsion systems—such as gas turbines and piston engines—are expected to remain dominant in the medium term. In this context, sustainable hydrocarbon-based aviation fuels represent a practical and necessary solution. Certified sustainable aviation fuel (SAF) pathways are currently approved exclusively for use in gas turbines, with certification standards tailored to turbine-specific requirements. Consequently, fuel properties such as cetane number and evaporation behavior are not included in existing specifications. However, when SAF-kerosene blends are used in
Kleissner, Florian, Hofmann, Peter, Vogd, Philipp, Vauhkonen, Ville, Käkölä, Jaana, Greve, Alina
The Aircraft nvPM Mission Emissions Estimation Methodology, Version 2 (MEEM2)2025-01-600010/13/2025
The nvPM Mission Emissions Estimation Methodology (MEEM) was previously developed to estimate nonvolatile particulate matter (nvPM) emissions from ground certification data using the publicly available data from the International Civil Aviation Organization (ICAO) Aircraft Engine Emissions Databank (EEDB). In order to potentially improve the accuracy of nvPM emissions estimation and to enhance its usefulness to modelers, the method was revised to make use of fuel flow correlations and similar altitude corrections as used in the Boeing Fuel Flow Method 2 (BFFM2). The new fuel flow approach allows for improved trade-off-type assessments between nvPM and gaseous emissions—i.e., less relative uncertainties when assessing results from the two methods. Like the former MEEM, the new method, MEEM2, can be used with just publicly available data such as nvPM emissions indices (EI) from the EEDB as well as predicted fuel flows from publicly available aircraft performance models. MEEM2 has been
Ahrens, Denise, Kim, Brian, Méry, Yoann, Zelina, Joseph, Dudebout, Rudolph, Miake-Lye, Richard C.
Optimal Sets of Molecules to Predict Aviation Fuel Properties2025-01-039510/07/2025
The complexity and variability of modern aviation fuels necessitate the development of robust and efficient tools to assess their properties accurately, particularly within the certification framework established by the American Society for Testing and Materials (ASTM). Therefore, previous research has developed predictive models to reduce the experimental burden by predicting aviation fuel properties from broad chemical classes. While two-dimensional Gas Chromatography (GC×GC) provides detailed compositional information, it only identifies the weight of hydrocarbon families (aromatics, cycloalkanes, n-alkanes, iso-alkanes), not individual molecules. Aviation fuels are complex, and their composition can contain more than 60 key classes, the majority of which are isomeric. As a result, an exceptionally high number of possible molecule combinations makes random selection prone to high errors in property prediction. To this end, we used a Monte Carlo approach to search for the optimal
Radaideh, Mohammed I., Kim, Doohyun, Radaideh, Majdi, Violi, Angela
A Life Cycle Assessment of Potential Pathways to Increase Sustainable Aviation Fuel Yields through CO 2 Upgrading Co-located with Corn Ethanol Production13-06-03-002309/04/2025
Alcohol-to-jet (ATJ) upcycling of ethanol to sustainable aviation fuel (SAF) is an attractive emerging pathway for SAF production, especially in the US Midwest with large-scale corn ethanol production. Only 39% of the corn carbon is converted to ethanol, 20% is emitted as CO2. Capturing the CO2 to produce additional ethanol or SAF directly can increase the carbon yield. To guide technology selection, this work used life cycle assessment for several CO2-to-SAF production pathways. Additionally, improvements for corn ethanol production were explored by replacing natural gas burners with heat pumps for corn drying, which reduced the carbon intensity of corn ethanol by nearly 16%. But subsequent upgrading of the ethanol to SAF is only 4.5–20% better than conventional aviation fuel. By contrast, CO2-based alternative routes to SAF fared better, reducing carbon intensities between 83% and 90%. Gas fermentation of CO2 to ethanol with subsequent ATJ upcycling to SAF was contrasted to Fischer
McCord, Stephen, Talsma, Sam, Bouchard, Jessey, Zavaleta, Victor Gordillo, He, Xin, Sick, Volker
Converting Waste Streams into BiofuelTBMG-5355208/01/2025
Made from renewable materials like biomass and agricultural waste, sustainable aviation fuel has enormous potential to decarbonize the aviation industry. But widespread adoption has yet to take off.
Aerospace Fuel System Specifications and StandardsAIR1408B (Current)07/16/2025
This report lists documents that aid and govern the design of aircraft and missile fuel systems. The report lists the military and industry specifications and standards and the most notable design handbooks that are commonly used in fuel system design. Note that only the principle fuel specifications for the U.S. and Europe (Military Specifications, ASTM, and Def Stan) have been included within this report. The specifications and standards section has been divided into two parts: a master list arranged numerically of all industry and military specifications and standards, and a component list that provides a functional breakdown and a cross-reference of these documents. It is intended that this report be a supplement to specifications ARP8615, MIL-F-17874, and JSSG 2009. Revisions and amendments which are correct for the specifications and standards are not listed. The fuel system design handbooks are listed for fuels and for system and component design.
AE-5A Aerospace Fuel, Inerting and Lubrication Sys Committee
Fuel Versus Oxygen: Evaluations and ConsiderationsAIR5648B (Current)07/09/2025
Current regulations (e.g., Title 14 of the United States Code of Federal Regulations, or 14 CFR) define design requirements for oxygen system provisions for protection of crewmembers and passengers following emergency events such as in-flight decompression. This aerospace information report (AIR) addresses the operational oxygen system requirements for a decompression incident that may occur at any point during a long-range flight, with an emphasis for a decompression at the equal time point (ETP). This AIR identifies fuel and oxygen management contingencies and presents possible solutions for the efficient, safe, and optimum fuel/oxygen flight continuation. Oxygen management is a critical concern for all aircraft, ranging from single-engine types operating above 10000 feet to complex, high-performance aircraft equipped with supplemental oxygen systems. Proper planning ensures compliance with regulations and supports pilot and passenger safety at higher altitudes. This document
A-10 Aircraft Oxygen Equipment Committee
Application of Sustainable Aviation Fuels in Compression Ignition Aviation Engines: In-Flight Investigations2025-01-031707/02/2025
To achieve a significant reduction in net CO₂ emissions in the aviation sector, sustainable aviation fuels (SAFs) are considered a key factor. Current research efforts are therefore focused on SAFs, which exhibit properties that differ from conventional kerosene, particularly in aspects critical to compression-ignition (CI) engines, such as cetane number, evaporation behavior or lubricity. These differences necessitate dedicated investigations to assess their suitability and performance in such engines. However, real operating conditions — such as intake air- and exhaust- pressure levels during flight — cannot be fully replicated on standard engine test benches. For this reason, real flight experiments were conducted to address these limitations. Notably, this work marks the first instance of in-flight testing of SAFs in CI aviation engines, constituting a significant milestone in this research area. In the course of these investigations, ASTM D7566 Annex A2-compliant HEFA
Kleissner, Florian, Reitmayr, Christian, Hofmann, Peter
Aircraft Fuel System and Component Icing TestARP1401C (Current)06/27/2025
This SAE Aerospace Recommended Practice (ARP) covers a brief discussion of the icing problem in aircraft fuel systems and the different means that have been used to test for icing. Fuel preparation and icing test procedures for aircraft fuel systems and components are proposed herein as a recommended practice to be used for fixed wing and rotary-wing aircraft within their operational environment. This ARP mostly addresses aircraft fuel system level testing and provides a means to address the requirements of FAR 14 CFR § 23.951(c), § 25.951(c), § 27.951(c), and § 29.951(c). In the context of this ARP, the engine and the auxiliary power unit (APU) are not considered to be components of the aircraft fuel system. However, some of the methods described in this document can be applied to the engine, APU, and other aircraft (system or component level) icing tests. This revision does not completely address new developments in ice accretion and release resulting from internal flow in tubing
AE-5A Aerospace Fuel, Inerting and Lubrication Sys Committee
Evaluation of Jet Fuels on Thermal Efficiency, NO X Emissions, Particulate Matter, and Particle Size Distribution in a Heavy-Duty Compression Ignition Engine2025-01-024406/16/2025
Alternative fuels such as Fischer-Tropsch Synthesized Paraffinic Kerosene (FT-SPK) and Catalytic Hydrothermal Conversion Jet (CHCJ) are among the important sustainable aviation fuels (SAFs) for future transportation. However, these alternative fuels often vary in their characteristics, depending on their feedstock and fuel production processes. Therefore, a detailed analysis of these alternative fuels' combustion, emissions, and efficiency must be performed under controlled experiments to understand the impact of fuel properties and operating conditions. This study used a single-cylinder research engine (SCE) with a compression ratio of 17:1. Extensive operating conditions were performed to determine the effect of each fuel on the engine performance, which can be fundamentally understood by fuel properties (e.g., cetane number, heat of combustion, and density) in comparison with Jet-A fuel. The experimental setup includes high-speed data acquisition for combustion analysis and gaseous
Cung, Khanh, Miganakallu Narasimhamurthy, Niranjan, Khalek, Imad, Hansen, Greg
Impact of Copper Contamination on the Thermal Stability of Jet FuelsAIR6443A (Current)05/27/2025
This SAE Aerospace Information Report (AIR) discusses the sources of copper in aviation jet fuels, the impact of copper on thermal stability of jet fuels and the resultant impact on aircraft turbine engine performance, and potential methods for measurement of copper contamination and reduction of the catalytic activity of copper contamination in jet fuels. This document is an information report and does not provide recommendations or stipulate limits for copper concentrations in jet fuels.
AE-5B Aircraft and Engine Fuel and Lubricant Sys Components
Impacts of Injection Pressure on Split-Injection Energy-Assisted Compression-Ignition Combustion of Low Cetane Number SAFs with a Gaussian-Shaped Ribbed Piston Bowl Design2025-01-835004/01/2025
The impact of injection pressure on a split-injection energy-assisted compression-ignition (EACI) combustion strategy was studied in an optically accessible engine with a custom ribbed piston bowl design. Three injection pressures (600, 800, and 1000 bar) were investigated for three split-injection dwells (1.5, 2.0, and 2.5 ms) with a fixed second injection timing of -5.0 CAD. The Gaussian-shaped ribbed piston bowl design was employed to position hot combustion gases from the first injection near the centrally located injector to enable rapid ignition and mixing-controlled combustion of the second injection. At 600-bar injection pressure, as injection dwell was shortened, relocation of hot combustion gases near the injector became increasingly more difficult due to less available time for relocation and due to the higher in-cylinder densities at the start-of-injection (SOI) for the first injection. Increased injection pressure (800 and 1000 bar) improved the relocation of the first
Amezcua, Eri, Stafford, Jacob, Kim, Kenneth, Kweon, Chol-Bum, Rothamer, David
A Conjugate Heat Transfer Numerical Framework Applied to Energy-Assisted Ignition of Jet Fuel in a Rapid Compression Machine2025-01-835204/01/2025
Airborne compression ignition engines operating with aviation fuels are a promising option for reducing fuel consumption and increasing the range of hybrid-electric aircraft. However, the consistent ignition of Jet fuels at high-altitude conditions can be challenging. A potential solution to this problem is to ignite the fuel sprays by means of a glow-plug-based ignition assistant (IA) device. The interaction between the IA and the spray, and the subsequent combustion event result in thermal cycles that can significantly affect the IA’s durability. Therefore, designing an efficient and durable IA requires detailed understanding of the influence that the IA temperature and insertion depth have on the complex physics of fuel-air mixture ignition and flame propagation. The objective of this study is to design a conjugate heat transfer (CHT) modeling framework that can numerically replicate F-24 Jet fuel spray ignition using a glow-plug-based IA device in a rapid compression machine (RCM
Oruganti, Surya Kaundinya, Lien, Hao-Pin, Torelli, Roberto, Motily, Austen, Lee, Tonghun, Kim, Kenneth, Mayhew, Eric, Kweon, Chol-Bum
Morphologies and Structures of Liquid Fragments Derived from the Near-Field Zone of a Twin-Orifice Swirl Atomizer2025-01-846104/01/2025
Aviation gas turbine engines typically utilize twin-orifice swirl atomizers to achieve a fine spray, widen the spray cone angle, and shorten spray penetration. However, using twin-orifice atomizers complicates the spray structure, and knowledge of the spray, especially in the near-field nozzle zone, remains limited. This study experimentally investigates the morphologies and structure of liquid fragments in the near-field nozzle of a twin-orifice atomizer. A high-speed backlit experimental system was developed to examine the liquid fragment morphologies and structures. The fragments are classified into spherical droplets, ligaments, and other irregular structural fragments. Results show that with increasing the pressure in the near field of the nozzle, the proportion of nearly round fragments decreases with increasing pressure. In contrast, the proportion of ligament-like fragments tends to increase. Besides, the particle size distribution did not change significantly within the 10 to
Pham Vu, Nam, Manh, Vu, Pham, Phuong Xuan, Nguyen, Kien Trung
Comprehensive Investigation of Combustion Characteristics, Emissions, and Tribological Properties of Synthetic Kerosene (S8) in a CVCC and CRDI Research Engine2025-01-844304/01/2025
There is a need to reduce both the greenhouse gas emissions of internal combustion engines, and the reliance on traditional fossil fuels like Ultra Low Sulfur Diesel (ULSD). In this research, a synthetic paraffinic kerosene fuel, designated S8 and created from natural gas feedstocks using the Fischer-Tropsch process was investigated to determine its autoignition and combustion characteristics, emissions, and tribological properties. This fuel, S8, was found to have a Derived Cetane Number (DCN) of 62, which reflects a shorter Ignition Delay (ID), and Combustion Delay (CD) compared to ULSD, which has a DCN of 48. However, due to the chemical properties of S8, it lacks sufficient lubrication qualities in comparison to ULSD, so addition of 3% methyl oleate by mass was used to improve lubricity. The shorter ignition delay of S8, initially observed in a Constant Volume Combustion Chamber (CVCC) and confirmed in a fired Common Rail Direct Injection (CRDI) experimental engine. Investigations
Soloiu, Valentin, Willis, James, Norton, Coleman, Davis, Zachary, Graham, Tristan, Nobis, Austin
SAE TOMORROW TODAY: A Breakthrough in Sustainable Aviation Fuel1350202/17/2025
We often hear about sustainable fuel options when it comes to vehicles, but what about aerospace? With aviation fuel demand expected to rise to 160 billion gallons per year by 2050, new and innovative Sustainable Aviation Fuel (SAF) pathways are certainly needed. In response, CleanJoule has developed a proprietary manufacturing process that produces SAF with 10% higher energy density than average Jet A fuel. This process utilizes abundant biomass residue to create a cost-effective, drop-in replacement for conventional jet fuel. To learn more, we sat down with Mukund Karanjikar CEO, to discuss CleanJoule's mission is to create accessible, affordable and abundant SAF and reduce the aerospace industry's reliance on fossil fuels. We'd love to hear from you. Share your comments, questions and ideas for future topics and guests to podcast@sae.org. Don't forget to take a moment to follow SAE Tomorrow Today--a podcast where we discuss emerging technology and trends in mobility with the leaders
Hineman, Marcie
Aerospace & Defense Technology: February 202525AERP0202/06/2025
The Art of Reverse Engineering Yesteryear for Aerospace and Defense Data Storage Drives Manufacturing Spotlight: Machining Complex Parts and Materials for Space Flight and Exploration Notre Dame's New Boundary Breaking Mach 10 Quiet Wind Tunnel Shape-Shifting Antenna Poised to Transform Communications British Army Completes First Test of Drone Killing Radio Frequency Weapon A Swarm of Sensors, Rovers and Astronauts Explore the 'Moon' Researchers at the German Aerospace Center have developed a new approach to networked communications that could theoretically occur on the Moon or in environments on Earth where conventional communications are unavailable. Army Researchers Examine Nanotechnology for Climate Solutions Army scientists are joining forces with experts from across the nation to tackle the climate crisis using the power of nanotechnology Airman Brings Fuel Sampling Innovation to Eglin, Possibly Air Force The U.S. Air Force is testing a new prototype single point nozzle adapter
Experimental Evaluation of Binary Iso-Dodecane/n-Dodecane Blends for Emulating Sooting Characteristics of Sustainable Aviation Fuels01-18-01-000302/06/2025
Sustainable aviation fuels (SAFs) derived from renewable sources are promising solutions for achieving carbon neutrality and further controlling aircraft engine emissions, operating costs, and energy security. These SAFs, primarily consist of branched and normal paraffins and exhibit significantly reduced sooting tendencies compared to conventional petroleum-based jet fuels, due to their lack of aromatics content. Our previous study investigated soot formation in non-premixed combustion for three ASTM-approved alternative jet fuels, namely Fischer–Tropsch synthetic paraffinic kerosene (FT-SPK), hydroprocessed esters and fatty acids from camelina (HEFA-Camelina), and alcohol-to-jet (ATJ), and demonstrated that the varying paraffinic composition within SAFs results in diverse sooting propensities, in the order of ATJ > FT-SPK > HEFA-Camelina. To evaluate the impact of iso-paraffins on sooting tendency and validate the suitability of utilizing binary blends of iso-dodecane (iC12) and
Xue, Xin, Sung, Chih-Jen, Wang, Xiaofeng
Airman Brings Fuel Sampling Innovation to Eglin, Possibly Air ForceTBMG-5252102/01/2025
With a few of snaps, turns and clicks, a new fuel innovation is sealed in place to an Air Force R-11 fuel truck. After that five-second attachment, it is ready to gather a required fuel sample for evaluation to ensure aircraft fuel is free of water or any other contamination.
Sustainable Aviation Fuel – An Effective Tool for Complying with the Aviation’s Global Environmental Commitment2024-36-006612/20/2024
The (commercial) aviation sector (passenger and freight), which is strongly engaged with the world efforts to mitigate the carbon emissions and their inherent climate change effects, has accounted in 2018 for 2.4 % of global carbon dioxide (CO2) emissions (pre-pandemic levels). Despite the reductions in air travel demand during the 2020 pandemic, with a reduction of up to 80% in passenger travel during the peak pandemic period, the air travel demand has already recovered to around 80% of the pre-pandemic level, with aviation emissions in 2022 reaching around 800 Mt CO2, accounting for 2% of the global energy related CO2 emissions. Moreover, the demand for air travel is expected to double by 2040, growing at an annual average rate of 3.4%, which means that. despite the efficiency improvement trend (average 2%/year), will almost double the aviation’s greenhouse (GHG) emissions, with a significant increase in its relative GHG share, compared to the other transport modes. Meanwhile the
Barbosa, Fábio Coelho
Effect of Fuel Chemical Structure on Soot Formation in Sustainable Aviation Fuels2024-01-431011/05/2024
Sustainable Aviation Fuels (SAFs) offer great promises towards decarbonizing the aviation sector. Due to the high safety standards and global scale of the aviation industry, SAFs pose challenges to aircraft engines and combustion processes, which must be thoroughly understood. Soot emissions from aircrafts play a crucial role, acting as ice nuclei and contributing to the formation of contrail cirrus clouds, which, in turn, may account for a substantial portion of the net radiative climate forcing. This study focuses on utilizing detailed kinetic simulations and soot modeling to investigate soot particle generation in aero-engines operating on SAFs. Differences in soot yield were investigated for different fuel components, including n-alkanes, iso-alkanes, cycloalkanes, and aromatics. A 0-D simulation framework was developed and utilized in conjunction with advanced soot models to predict and assess soot processes under conditions relevant to aero-engine combustion. The simulations
Yi, Junghwa, Manin, Julien, Wan, Kevin, Lopez Pintor, Dario, Nguyen, Tuan, Dempsey, Adam
Operation of a Compression-Ignition Kerosene Aviation Engine with Sustainable Aviation Fuel: An Experimental Study2024-01-600510/28/2024
The aviation industry is undergoing environmental scrutiny due to its significant greenhouse gas emissions. Sustainable aviation fuels (SAFs) are a vital solution for reducing carbon emissions and pollutants, aligning with global efforts for carbon-neutral aviation growth. SAFs can be produced via multiple production routes from different feedstock, resulting in significantly different physical and chemical fuel properties. Their suitability in a compression-ignition (CI) aircraft engine was evaluated through test bench investigations at TU Wien - Institute of Powertrain and Automotive Technology in partnership with Austro Engine. ASTM D7566-certified fuels like Hydrotreated Vegetable Oil (HVO), Fischer–Tropsch–Kerosene (FTK) or Alcohol to Jet (AtJ), but also an oxygen containing biodiesel have been tested extensively. Gaseous emissions, soot emissions, indication measurement data, efficiencies, and the like were acquired and comprehensively analyzed for engine operation with different
Kleissner, Florian, Hofmann, Peter
Optical Equipment Safety in Aircraft Fuel TanksARP7977 (Current)08/01/2024
The recommended practices of this document are intended for optical devices and associated optical cables and connectors installed inside transport category aircraft or environments of equivalent ignitability. This document covers optical radiation in the wavelength range from 380 nm to 10 μm. As explained in this document, wavelengths below this range are capable of igniting fuel-air mixtures through an ignition mechanism not considered at this issue of ARP7977. Use of wavelengths outside the range 380 nm to 10 μm should be discussed with the relevant Certification Authority.
AE-5A Aerospace Fuel, Inerting and Lubrication Sys Committee
Experimental and Numerical Investigations of a Dual-Fuel Hydrogen–Kerosene Engine for Sustainable General Aviation2024-01-600106/17/2024
Reducing CO2 emissions is an increasingly important issue. In aviation, approaches such as e-propulsion only represent a solution for special applications due to the low energy density of batteries. Because of the low-cost and robust design of combustion engines, this concept is still the most suitable for general aviation. For defossilization, besides e-fuels and bio-fuels, which represent the so-called sustainable aviation fuels (SAF), hydrogen can serve as a promising energy carrier for CO2 reduction. For this purpose, the combustion process of a dual-fuel hydrogen–kerosene (Jet A-1) engine was developed and investigated for use in small aircrafts. This study explores the influence of hydrogen addition on combustion parameters, emissions, and efficiency. An advantage of this special design as dual-fuel engine (hydrogen and kerosene) is the possibility of redundancy operation in the event of a H2 fuel system failure as well as full operational capability of the aircraft in the event
Reitmayr, Christian, Wiesmann, Frederik, Gotthard, Thomas, Hofmann, Peter
Electrification and Autonomy: Vol. 1EPRCOMPV33202305/10/2024
David, Aharon, Muelaner, Jody E., Rezende, Rene Nardi
Compression Ignition Engine Smoke Emissions at Reduced Ambient Pressures and Temperatures2024-01-238004/09/2024
Smoke emission from compression ignition (CI) engines is directly tied to fuel atomization, vaporization, mixing and combustion processes. Engine boundary conditions such as ambient pressures and temperatures, particularly at higher altitudes, have significant impacts on both available ignition energy and on the mixing-controlled combustion process. However, the effects of boundary conditions are difficult to explore without thorough pressure and temperature control of the engine intake air and exhaust gas at higher altitude conditions. The objective of this research is to investigate the relationship between engine smoke emission and engine power in a CI engine fueled with jet fuel at various ambient conditions including higher altitudes. A multi-cylinder compression-ignition engine was operated on a jet fuel at various ambient pressure and temperature conditions, as low as 60 kPa and -12°C, respectively. Single and multi-injection strategies were applied depending on engine power
Mattson, Jonathan, Gibson, Joseph, Kweon, Chol-Bum, Kim, Kenneth, Schroen, Erik, Hepp, Kyle, Meininger, Rik, Clerkin, Peter, Kruger, Kurt, Musser, Marshall, Pope, Aaron, Kang, Sang-Guk
Impact of a Split-Injection Strategy on Energy-Assisted Compression-Ignition Combustion with Low Cetane Number Sustainable Aviation Fuels2024-01-269804/09/2024
The influence of a split-injection strategy on energy-assisted compression-ignition (EACI) combustion of low-cetane number sustainable aviation fuels was investigated in a single-cylinder direct-injection compression-ignition engine using a ceramic ignition assistant (IA). Two low-cetane number fuels were studied: a low-cetane number alcohol-to-jet (ATJ) sustainable aviation fuel (SAF) with a derived cetane number (DCN) of 17.4 and a binary blend of ATJ with F24 (Jet-A fuel with military additives, DCN 45.8) with a blend DCN of 25.9 (25 vol.% F24, 75 vol.% ATJ). A pilot injection mass sweep (3.5-7.0 mg) with constant total injection mass and an injection dwell sweep (1.5-3.0 ms) with fixed main injection timing was performed. Increasing pilot injection mass was found to reduce cycle-to-cycle combustion phasing variability by promoting a shorter and more repeatable combustion event for the main injection with a shorter ignition delay. For both fuels, dwells between 2.0 and 2.5 ms
Stafford, Jacob, Amezcua, Eri, Miganakallu Narasimhamurthy, Niranjan, Kim, Kenneth, Kweon, Chol-Bum, Rothamer, David
Zero Carbon Emission Aviation Fuel Technology Review - The Hydrogen Pathway2023-36-002901/08/2024
The commercial aviation currently accounts for roughly 2.5 % of the global CO2 emissions and around 3.5% of world warming emissions, taking into account non CO2 effects on the climate. Its has grown faster in recent decades than the other transport modes (road, rail or shipping), with an average rate of 2.3%/year from 1990 to 2019, prior to the pandemic. Moreover, its share of Greenhouse (GHG) emissions is supposed to grow, with the increasing demand scenario of air trips worldwide. This scenario might threaten the decarbonization targets assumed by the aviation industry, in line with the world efforts to minimize the climate effects caused by the carbon emissions. In this context, hydrogen is set as a promising alternative to the traditional jet fuel, due to its zero carbon emissions. Furthermore, its high energy content makes it suitable for the aviation industry, especially in the short to medium haul flights niche, that currently accounts for around 43.8% of global aviation CO2
Barbosa, Fábio Coelho
Emissions of Aerospace Fuels F-24 and Jet-A in a Jet Engine and Correlation with Combustion Characteristics from a Constant Volume Combustion Chamber2023-01-166610/31/2023
An investigation into emissions differences and their correlations with differing combustion characteristics between F24 and Jet-A was conducted. Raw emissions data was taken from a single stage jet engine by a FTIR gas analyzer. Measurements of H2O, CO2, CO, NOx, and total hydrocarbon emissions (THC) were taken at 60K, 65K, and 70K RPM. At 70K RPM Jet-A and F-24 the emissions were similar at approx.: 4% H2O, 3% CO2, 970 PPM CO, 28 PPM NOx. Jet-A THC emissions were approx.: 1200 PPM THC, F24 THC emissions were lower by over 60%. The significantly lower amount of THC emissions for F24 suggests more complete combustion compared to Jet-A.
Soloiu, Valentin, Rowell, Aidan, Weaver, Amanda, Mcafee, John, Willis, James, O'Brien, Brandon
Comparative Analysis of the Lubrication, Friction, and Wear of Injection System Materials, with Synthetic Paraffinic Kerosene, Jet-A, and ULSD2023-01-163310/31/2023
Alternative fuels are sought after because they produce lower emissions and sometimes, they have feedstock and production advantages over fossil fuels, but their wear effects on engine components are largely unknown. In this study, the lubricity properties of a Fischer-Tropsch Gas-to-Liquid alternative fuel (Synthetic Paraffinic Kerosene-S8) and of Jet-A fuel were investigated and compared to those of Ultra Low Sulphur Diesel (ULSD). A pin-on-disk tribometer was employed to test wear and friction for a material pair of an AISI 316 steel ball on an AISI 1018 steel disk when lubricated by the fuels in this research work. Advanced digital microscopy was used to compare the wear patterns of the disks. Viscosity and density analysis of the tested fluids were also carried out. Tribometry for the fuel showed that S8 fell between Jet-A and ULSD when friction force was calculated and showed higher wear over time and after each test when compared to that of Jet-A and ULSD. An initially higher
Soloiu, Valentin, Davis, Zachary, Molina, Gustavo J., Myrthil, Christopher, Willis, James, Weaver, Amanda
Development of a Laboratory Unit to Study Internal Injector Deposits Formation2023-24-007808/28/2023
The formation of deposits in the fuel systems of heavy-duty engines, using drop-in fuels, has been reported in recent years. Drop-in fuels are of interest because they allow higher levels of alternative fuels to be blended with conventional fuels that are compatible with today’s engines. The precipitation of insolubles in the drop-in fuel can lead to clogging of fuel filters and internal injector deposits, resulting in increased fuel consumption and engine drivability problems. The possible mechanisms for the formation of the deposits in the fuel system are not yet fully understood. Several explanations such as operating conditions, fuel quality and contamination have been reported. To investigate injector deposit formation, several screening laboratory test methods have been developed to avoid the use of more costly and complex engine testing. To further evaluate and understand the formation of internal injector deposits in heavy-duty engines, a thermal laboratory test method has been
Pach, Mayte, Hittig, Henrik, Scholle, Tobias, Kusar, Henrik, Engvall, Klas
Experimental and Numerical Investigation of Combustion and Noise, Vibrations, and Harshness Emissions in a Drone Jet Engine Fueled with Synthetic Paraffinic Kerosene01-17-01-000608/14/2023
Emissions and effects of climate change have prompted study into fuels that reduce global dependence on traditional fuels. This study seeks to investigate engine performance, thermochemical properties, emissions, and perform NVH analysis of Jet-A and S8 using a single-stage turbojet engine at three engine speeds. Experimental Jet-A results were used to validate a CFX simulation of the engine. Engine performance was quantified using thermocouples, pressure sensors, tachometers, flow meters, and load cells fitted to the engine. Emissions results were collected using an MKS Multigas Emissions Analyzer that examined CO, CO₂, H₂O, NOx, and THC. NVH analysis was conducted using a multifield, free-field microphone, and triaxial accelerometer. This study found that Jet-A operates at higher temperatures and pressures than S8, and S8 requires higher fuel flow rates than Jet-A, leading to poorer efficiency and thrust. S8 produced stronger vibrations over 5 kHz compared to Jet-A. S8 showed a
Soloiu, Valentin, Mcafee, John, Ilie, Marcel, Rowell, Aidan, Willis, James, Dillon, Nicholas
On-Board Fuel Sensing for UAS and Ground Vehicle Applications2024-01-412808/10/2023
The variability in fuel, particularly for fuel blends containing sustainable aviation fuels (SAFs), emphasizes the importance of understanding fuel properties for optimizing engine performance. This paper introduces spectroscopic fuel sensors capable of real-time estimation of jet fuel properties, mainly derived cetane number (DCN). While initially developed for unmanned aircraft systems (UAS), the paper explores their potential in ground vehicle applications: enhancing engine performance through sensing for feed-forward control and fuel property monitoring at fuel depots. The fuel sensing technologies are based on spectroscopic techniques coupled with machine learning (ML) approaches. The combination of these techniques demonstrates a promising solution for a wide spectrum of fuel applications.
Patel, Dev B., Sutar, Ashish, Abraham, Abhinav, Ambre, Dhananjay, Brezinsky, Kenneth, Lynch, Patrick T., Okada, Haruna, Stafford, Jacob M., Miganakallu, Niranjan, Sanders, Scott, Rothamer, David, Mayhew, Eric, Kim, Kenneth S.
Extension of Diesel Engine Power via Electrically Assisted Turbocharger2024-01-413608/10/2023
The power demand for unmanned ground systems (UGS) and unmanned aircraft systems (UAS) has been ever-increasing to support important military operations. Mild hybridization technologies have the potential to address the ever-increasing power demand. The objective of this study is to investigate the capability of an electrically assisted turbocharger (EAT) as one mild hybridization method. A motor-generator (M/G) was integrated to a turbocharger to generate electricity using the engine exhaust energy, or to spin the turbocharger using the energy stored in energy storage device. The EAT was implemented to a 2-liter turbocharged direct-injection diesel engine fueled with jet fuel. Then, the operation of the EAT was examined and the results were compared to the baseline. The target manifold pressure was regulated by the M/G, which applies varying amounts of positive or negative torque to increase or decrease the speed of the EAT. The energy recovered from the exhaust stream and converted
Kang, Sang-Guk, Schroen, Erik S., Mattson, Jonathan M., Kim, Kenneth S., Hepp, Kyle D., Kruger, Kurt M., Clerkin, Peter J., Kweon, Chol-Bum M., Gibson, Joseph A., Meininger, Rik D., Musser, Marshall R.
Performance of a Diesel Engine Run with Kerosene–Rapeseed Oil Blends Doped with Ignition Promoters04-17-02-000807/31/2023
The use of straight vegetable oil in diesel engines leads to undesirable consequences due to the peculiar physicochemical properties of vegetable oils. In this regard, the use of pure and unmodified vegetable oils requires their obligatory dilution with petroleum fuels, usually diesel fuel. However, blends of diesel fuel with vegetable oil have a significantly higher density and viscosity than pure diesel fuels. Therefore, in this article, it was proposed to use blends of vegetable oil with aviation kerosene since kerosene has lower density and viscosity compared to diesel fuel. In addition, kerosene is less prone to coking of injectors, has a higher calorific value, and has a lighter hydrocarbon composition, which makes starting the engine easier. Within the framework of the study, engine tests of a full-size four-cylinder diesel engine, MMZ D-245.12.C, were carried out at maximum load in the range of crankshaft speeds from minimum (1000 min−1) to nominal (2400 min−1). Various blends
Cherepanova, Anna, Ukhanov, Denis, Savel’ev, Evgeniy, Sapunov, Valentin
Monitoring Melting Ice Formations in Aircraft Fuel Tank by Acoustic Emission2023-01-143706/15/2023
Considerable amounts of water accumulate in aircraft fuel tanks due to condensation of vapor during flight or directly during fueling with contaminated kerosene. This can result in a misreading of the fuel meters. In certain aircraft types, ice blocks resulting from the low temperatures at high altitude flights or in winter time can even interfere with the nozzles of the fuel supply pipes from the tanks to the engines. Therefore, as part of the maintenance operations, water has to be drained in certain intervals ensuring that no remaining ice is present. In the absence of an established method for determining residual ice blocks inside, the aircraft operator has to wait long enough, in some cases too long, to start the draining procedure, leading potentially to an unnecessary long ground time. A promising technology to determine melting ice uses acoustic signals generated and emitted during ice melting. With acoustic emissions, mainly situated in the ultrasonic frequency range, a very
Pfeiffer, Helge, Reynaert, Johan, Seveno, David, Jordaens, Pieter-Jan, Ceyhan, Ozlem, Wevers, Martine
Decarbonized Fuel Options for Civil AviationEPR202301206/13/2023
Drop-in replacement biofuels and electrofuels can provide net-zero CO2 emissions with dramatic reductions in contrail formation. Biofuels must transition to second-generation cellulosic feedstocks while improving land and soil management. Electrofuels, or "e-fuels,” require aggressive cost reduction in hydrogen production, carbon capture, and fuel synthesis. Hydrogen has great potential for energy efficiency, cost reduction, and emissions reduction; however, its low density (even in liquid form) combined with it’s extremely low boiling temperature mean that bulky spherical tanks will consume considerable fuselage volume. Still, emerging direct-kerosene fuel cells may ultimately provide a superior zero-emission, energy-dense solution. Decarbonized Power Options for Civil Aviation discusses the current challenges with these power options and explores the economic incentives and levers vital to decarbonization. Until common and enforceable global carbon pricing arrives, targeted national
Muelaner, Jody E.
Connectors, Electric, Circular, Miniature, Rack and Panel or Push-Pull Coupling, Environment ResistingAS81703B (Current)05/19/2023
This specification covers three series of environment resisting, circular, miniature electrical connectors (plugs and receptacles) with removable crimp and/or nonremovable solder contacts, and accessories. The connectors are only recommended for replacement and are not specified for aircraft applications (refer to AS50881).
AE-8C1 Connectors Committee
Model Selection for Predicting the Evaporation Rate of Aviation Fuels2023-01-502805/18/2023
The prediction of accurate evaporation rates for aviation fuels, which are complex mixtures of hundreds of hydrocarbon components with varying evaporation characteristics, remains a challenge. Multi-component vaporization models, such as distillation curve (DC) and diffusion limit (DL), are capable of predicting evaporation rates well but require the construction of surrogate fuels, which is difficult. Mono-component models, on the other hand, can be used for rapid evaporation conditions similar to those in a heat engine combustion chamber, with acceptable uncertainties. However, the accuracy of these models under engine-relevant operating conditions is unclear. This study aims to address this research gap by experimentally measuring the evaporation rates of two aviation fuels (TS-1 and Jet-A1) at different temperature conditions and evaluating the feasibility of current theoretical models for predicting evaporation rates under engine-relevant conditions. The study found that current
Pham Vu, Thanh Nam, Pham Xuan, Phuong, Nguyen Trung, Kien
Combined Impacts of Engine Speed and Fuel Reactivity on Energy-Assisted Compression-Ignition Operation with Sustainable Aviation Fuels2023-01-026304/11/2023
The combined impacts of engine speed and fuel reactivity on energy-assisted compression-ignition (EACI) combustion using a commercial off-the-shelf (COTS) ceramic glow plug for low-load operation werexxz investigated. The COTS glow plug, used as the ignition assistant (IA), was overdriven beyond its conventional operation range. Engine speed was varied from 1200 RPM to 2100 RPM. Three fuel blends consisting of a jet-A fuel with military additives (F24) and a low cetane number alcohol-to-jet (ATJ) sustainable aviation fuel (SAF) were tested with cetane numbers (CN) of 25.9, 35.5, and 48.5. The ranges of engine speed and fuel cetane numbers studied are significantly larger than those in previous studies of EACI or glow-plug assisted combustion, and the simultaneous variation of engine speed and fuel reactivity are unique to this work. For each speed and fuel, a single-injection of fixed mass was used and the start of injection (SOI) was swept for each IA power. A maximum pressure rise
Stafford, Jacob, Amezcua, Eri, Miganakallu Narasimhamurthy, Niranjan, Kim, Kenneth, Kweon, Chol-Bum, Rothamer, David
Combustion Characteristics of Low DCN Synthetic Aviation Fuel, IPK, in a High Compression Ignition Indirect Injection Research Engine2023-01-027204/11/2023
The Coal-To-Liquid (CTL) synthetic aviation fuel, Iso-Paraffinic Kerosene (IPK), was studied for ignition delay, combustion delay, pressure trace, pressure rise rate, apparent heat release rate in an experimental single cylinder indirect injection (IDI) compression ignition engine and a constant volume combustion chamber (CVCC). Autoignition characteristics for neat IPK, neat Ultra-Low Sulfur Diesel (ULSD), and a blend of 50%IPK and 50% ULSD were determined in the CVCC and the effects of the autoignition quality of each fuel were determined also in an IDI engine. ULSD was found to have a Derived Cetane Number (DCN) of 47 for the batch used in this experimentation. IPK was found to have a DCN of 25.9 indicating that is has a lower affinity for autoignition, and the blend fell between the two at 37.5. Additionally, it was found that the ignition delay for IPK in the CVCC was 5.3 ms and ULSD was 3.56 ms. This increase in ignition delay allowed the accumulation of fuel in the combustion
Soloiu, Valentin, Weaver, Amanda, Smith, Richard, Rowell, Aidan, Mcafee, John, Willis, James
Comparison and Evaluation of Engine Wear, Engine Performance, NOx Reduction and Nanoparticle Emission by using Gasoline, JP-8, Karanja Oil Methyl Ester Biodiesel, and Diesel in a Military 720 kW, Heavy-Duty CIDI Engine Applying EGR with Turbo Charging2023-01-031804/11/2023
Rapid depletion of petroleum crude oil resources, stringent regulations on gaseous emission, and global warming due to exhaust pollution have compelled us to use the alternative of diesel fuel. Biodiesel is a green alternative fuel that can be produced from edible as well as non-edible vegetable oils, waste cooking frying oils, and animal fats. Biodiesel is an oxygenated, bio-gradable, renewable, non-sulfur, and non-toxic fuel. JP-8 is an aviation turbine fuel and is readily available. Gasoline fuel is also available in surplus. Under the multi-fuel strategy program, optimization of fuel availability is required for both, military combat as well as highway commercial heavy-duty vehicles. It was essential to assess the performance, NOx reduction, nanoparticle emission, and engine wear by using Gasoline, JP-8, and esterified Karanja oil biodiesel fuels on a military heavy-duty diesel engine. EGR is a useful technique to reduce NOx emissions. A Military heavy-duty,12-cylinders,720 kW
Pandey, Anand Kumar, Nandgaonkar, Milankumar, Varghese, Anil, sonawane, C, Kohil, Ritesh, Warke, Arundhati
Fuel Flow Rates for Jet-Powered Commercial Aircraft Taxi OperationsAIR8035 (Current)04/04/2023
This SAE Aerospace Information Report (AIR) summarizes prior empirical findings (AIAA 2018-3991; Chati, 2018) to recommend a modified baseline fuel flow rate model for jet-powered commercial aircraft during taxi operations on the airport surface that better reflects operational values. Existing standard modeling approaches are found to significantly overestimate the taxi fuel flow rate; therefore, a modified multiplicative factor is recommended to be applied to these existing approaches to make them more accurate. Results from the analysis of operational flight data are reported, which form the basis for the modeling enhancements being recommended.
A-21 Aircraft Noise Measurement Aviation Emission Modeling
Hydrogen Fuel System for Aircraft2023-01-097603/07/2023
Hydrogen propulsion is crucial for achieving zero carbon emissions in commercial aviation. The aircraft’s power can be generated through hydrogen combustion in a gas turbine engine and electricity through the fuel cell. Though promising, it poses several challenges for implementation, such as the large volume and structural modification required to carry cryogenic liquid hydrogen (LH2). Also, the current jet fuel system used in commercial aviation needs significant changes to incorporate hydrogen aircraft. The primary objective of this study was to analyze the Hypothesis related to Liquid Hydrogen Aircraft, which will help define the hydrogen fuel system. The theories were: A pressurization system is essential to maintain the LH2 tank pressure within the safe limit, Gaseous hydrogen transformed from Liquid Hydrogen is suitable for tank pressurization, Possible to maintain Cryogenic tank conditions during night non-operation time. A simplified Aircraft Hydrogen system was modeled and
Sarkar, Subrata, Grandi, Giada, Patel, Sahil
Mathematical Modeling of Refueling Restrictions of Aircraft Wing Tank2023-01-100403/07/2023
Refueling operation of the aircraft fuel tanks has some limitations. One of the limitations is refueling time which restricts refueling duration for entire tank. Other one is overfilling situations which are also possible because of the wave damper designs in tank such as barriers and baffles resist against fuel creeping towards all sides of tank. Required refueling duration restricts refueling speed at a certain minimum value. On the other hand, baffle design restricts refueling speed at a certain maximum value. It should be the mathematical region between these two extremum points where the refueling mass flow rate can be defined. Minimum mass flow rate point can be adjusted with defining of mass flow rate depends of requirements easily but upper extremum point should be defined depends on design of baffles. It can only be changed with altering the design of interior wing tank. In that paper mathematical model of the tank interior volumes and its components are established in order
Karahan, Kerem, Özdemir, Onur
Synthetic Jet Fuels from Non-Petroleum Feed StocksAIR6148 (Current)02/20/2023
This SAE Aerospace Information Report (AIR) provides general information on the developing subject of synthetic jet fuels derived from non-petroleum feed stocks. It addresses synthetic jet fuel properties and other topics associated with their use and is intended as a guide to assist aviation fuel system designers in considering important information on fuel properties when designing aircraft fuel systems and components. The AIR is limited to “drop-in” fuels that meet the requirements of the respective fuel specifications and are compatible with typical aircraft and ground refueling systems. While some key properties are included in this AIR for discussion, the reader should utilize documents such as MIL-HDBK-510 or the ASTM International research reports for a more-detailed review of fuel properties. AIR7484 also gives more details on fuel properties, specifically as they relate to airframe fuel system design.
AE-5A Aerospace Fuel, Inerting and Lubrication Sys Committee
Aircraft Aerodynamic Technology Review - A Tool for Aviation Performance and Sustainability Improvement2022-36-002202/10/2023
The aviation industry (passenger and freight), which currently accounts for 2.5% of the global CO2 emissions (1.9% of global greenhouse gas (GHG) emissions), is continuously under pressure to reduce its environmental footprint, given its historical and forecasted environmental track, strongly affected by the remarkable air traffic volume increase rates, albeit with a slower growth in emissions, due to the massive aviation's efficiency improvements, driven by the in the design and technology(more efficient and larger) aircrafts; improved operational practices and increased load factors (more passengers and freight per flight). Nevertheless, it has not been enough to tackle the rapidly increasing CO2 emissions (26% in the 2013-2018 timeframe and expected to continue increasing), which ultimately could grow between 2.4 and 3.6 times by 2050. This scenario has driven governments and the aviation industry to adjust their short term actions and develop a long-term decarbonization agenda
Coelho Barbosa, Fábio
Adhesive, Film Form Metallic Structural Sandwich ConstructionAMSA25463 (Current)10/04/2022
This specification covers the requirements for adhesives in film form for bonding metal facings to metal cores and to metal components of sandwich panels which are intended for use in primary and secondary structural airframe parts that may be exposed to temperatures up to 500°F (260°C).
AMS P17 Polymer Matrix Composites Committee
Bubble-Point Test MethodARP901B (Current)09/30/2022
This test method describes a procedure for measuring the largest pore or hole in a filter or similar fluid-permeable porous structure. A standard referee test method for precise determination or resolution of disputes is specified. A simpler inspection test procedure for quality assurance “go-no-go” measurement is also given. Bubble-point testing physics, analysis of bubble-point test data, and correlation with other methods of pore size determination are separately discussed in the appendix.
A-6C1 Fluids and Contamination Control Committee
Lignin-Based Jet Fuel Packs More PowerTBMG-4657009/01/2022
An experimental plant-based jet fuel could increase engine performance and efficiency, while dispensing with aromatics, the pollution-causing compounds found in conventional fuels, according to new research.
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