Year 3 of the National Jet Fuels Combustion Program: Practical and Scientific Impacts of Alternative Jet Fuel Research

Heyne, Joshua S.; Peiffer, Erin; Colket, Meredith B.; Jardines, Aniel; Shaw, Cecilia; Moder, Jeffrey P.; Roquemore, W. M.; Edwards, James T.; Li, Chiping; Rumizen, Mark; Gupta, Mohan L.

doi:10.2514/6.2018-1667

Cited by 28 publications

(16 citation statements)

References 16 publications

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“…64,66 DCN, a measure of the propensity of a fuel-air mixture to autoignite, spans a wide range from 17 to 74 relative to the range of 40 to 60 which current aviation fuels exhibit. 37,49 Reported values of DCN for all the fuels, with the exception of J-1 are located in Edwards. 39 J-1 was measured using the same ASTM standard at AFRL/UDRI.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Lean Blowoff in a Toroidal Jet-Stirred Reactor: Implications for Alternative Fuel Approval and Potential Mechanisms for Autoignition and Extinction

et al. 2020

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Sustainable aviation fuels (SAFs) have been identified as a method to reduce the aviation sector's environmental impact through carbon mitigation. Current certification processes of potential, viable SAFs require labor cost intensive assessments with investigation into combustor performance parameters related to fuel effects such as lean blowoff (LBO) where there exists the competition between multiphase physics and chemical kinetics of the fuel. Recent efforts show LBO effectively scales with the evaporative, mixing, and chemical time scales of a given combustor. Here, a toroidal jet-stirred reactor (TJSR), an experimental configuration meant to emulate perfectly stirred reactor (PSR) studies, is used to study the effects of fuel chemistry physical time scales on LBO while mitigating and minimizing the effects of evaporation mixing, respectively. For this investigation, six fuels/fuel mixtures spanning a range of derived cetane number (DCN) were evaluated in a lean premixed, prevaporized environment with engine relevant characteristics such as recirculation inlet temperature residence times (P = ∼1 atm, T = 460 K, τ = 5.5−6.5 ms). Gas phase emissions sampled within the reactor were measured with a Fourier transform infrared spectrometer to gain insight into relevant trends in species production for varying fuels as leaner conditions were approached. LBO in the TJSR was correlated with the parameters of the DCN and radical index, an indicator of OH production, signifying competition between the chemical processes of autoignition and extinction, respectively; these observations deviate from the established PSR theory for ignition extinction physics. However, the emergence of these correlations in the TJSR experiment support the importance of low temperature chemistry and flame robustness. A physical time scale approach to LBO is applied to the current experiment to elucidate the competition of autoignition and extinction phenomena. Knowledge of the physical LBO time scales and their relationship to chemical fuel properties suggest that the holistic LBO time scale may be viable as a preliminary screening metric for SAF certification.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Lean Blowoff in a Toroidal Jet-Stirred Reactor: Implications for Alternative Fuel Approval and Potential Mechanisms for Autoignition and Extinction

et al. 2020

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“…Therefore, it stands to reason that, if a fuel can adversely affect the atomisation of a given fuel injector, the vast majority of which have been optimised for use with Jet A and Jet A-1, this would affect the combustion instability characteristics of the engine (3,4) . With the increasing use of alternative fuels, several studies that discuss the spray characteristics of alternative fuels have been published recently times (5)(6)(7)(8)(9) . 'Atomisation' is a term used to describe in essence the transformation of liquid fuel into small droplets or a spray before being burned in a gas turbine combustor or any other liquid fuel burner.…”

Section: Introductionmentioning

confidence: 99%

“…The importance of fuel injection methods and their fuel atomisation characteristics has been well described in literature (1,5,6,(20)(21)(22)(23)(24)(25)(26) . Also, there are large number of studies in literature detailing the impact of the bulk properties of conventional fuels on atomisation and spray characteristics (5,7,8,12) . However, there is a lack of knowledge on how different alternative fuels, especially with selected aromatics species, and their properties impact the atomisation and spray characteristics.…”

Section: Introductionmentioning

confidence: 99%

Impact of aromatic species selection and micro and bulk properties of alternative fuels on atomisation

Wijesinghe¹,

Khandelwal

2021

Aeronaut. j.

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The importance of fuel injection methods and their atomisation characteristics has been well described in literature. Also, there are a large number of studies in literature detailing the impact of bulk properties of conventional fuels on atomisation and spray characteristics. However, there is a lack of knowledge on how different alternative fuels, and specifically aromatic species, impact spray and atomisation characteristics. In this investigation, the impact of alternative fuels, selected aromatic species and their properties on spray atomisation was studied. Details of how different aromatic structures, bonds and other micro properties of aromatics species impact spray and atomisation characteristics were investigated. To achieve this objective, testing was conducted using a Rolls-Royce Tay engine fuel injector. It was found that the droplet sizes in the form of the Sauter Mean Diameter (SMD) correlate well with fuel properties including density, viscosity and surface tension, which is in line with other published literature. Moreover, it was found that there are several aromatic species (ethylbenzene, cumene and tert-butylbenzene) which display improved atomisation. This indicates that the size of the aliphatic groups attached to the benzene ring in the aromatic molecule impact on the drop size and thereby the combustion characteristics. The worst performers were polyaromatic naphthalene compounds. With the increasing push for fuels with selected aromatic species in the future, this study provides knowledge on the impact of their on the atomisation characteristics.

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“…These estimates do not include overhead costs for all parties involved in the process or the cost of supplying large quantities of potentially expensive test fuel [10]. Because of the nature of this costly and volume-intensive testing process, the National Jet Fuels Combustion Program's (NJFCP) mission is to streamline the SAF approval process and, in turn, reduce the carbon intensity of aviation transportation by ensuring a broad and diverse portfolio of SAF fuels, feedstock, and processing technologies [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…The current certification process for SAF via ASTM D4054 has no specification limit for surface tension. However, surface tension is strongly and positively correlated with density, and there is a specification limit for density in all Category A fuels [11,12].…”

Section: Introductionmentioning

confidence: 99%

Orthogonal Reference Surrogate Fuels for Operability Testing

2020

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The approval and evaluation process for sustainable aviation fuels (SAF) via ASTM D4054 is both cost- and volume-intensive, namely due to engine operability testing under severe conditions. Engine operability tests of combustor under figures of merit (FOM) limit phenomena are the fuel effects on lean blowout, high-altitude relight, and cold-start ignition. One method to increase confidence and reduce volume in tiered testing is to use surrogate fuels for manipulation of properties. Key fuel performance properties (surface tension, viscosity, density) for cold-start ignition was determined prior to this study. Prior work regarding this FOM has not considered the combination of these properties. A surface tension blending rule was validated and incorporated into the jet fuel blend optimizer (JudO). A generalized surrogate calculator for N-dimensional surrogate components and features was developed. Jet fuel surrogates developed in this study were a mixture of conventional and sustainable aviation fuels instead of pure components. These surrogates suggested to be tested in this study could illuminate near worst-case effects for sustainable aviation fuel in a given configuration/rig. With those scenarios tested, we can further understand the influence on the key properties relative to cold-start ignition. This work and supporting experimental evidence could potentially lower the barrier for SAF approval processes.

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Year 3 of the National Jet Fuels Combustion Program: Practical and Scientific Impacts of Alternative Jet Fuel Research

Cited by 28 publications

References 16 publications

Lean Blowoff in a Toroidal Jet-Stirred Reactor: Implications for Alternative Fuel Approval and Potential Mechanisms for Autoignition and Extinction

Lean Blowoff in a Toroidal Jet-Stirred Reactor: Implications for Alternative Fuel Approval and Potential Mechanisms for Autoignition and Extinction

Impact of aromatic species selection and micro and bulk properties of alternative fuels on atomisation

Orthogonal Reference Surrogate Fuels for Operability Testing

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