An Overview of the National Jet Fuels Combustion Program

Colket, Meredith B.; Heyne, Josh; Rumizen, Mark; Edwards, James T.; Gupta, Mohan L.; Roquemore, W. M.; Moder, Jeffrey P.; Tishkoff, Julian M.; Li, Chiping

doi:10.2514/6.2016-0177

Cited by 33 publications

(15 citation statements)

References 20 publications

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“…The small droplets are expected to evaporate first because they have a larger surface area to volume ratio than larger droplets. The evaporation of the small C-5 droplets before those of C-1 and A-2 is consistent with C-5's flat boiling curve (0 to 95 percent distillation between 155°C and 165°C) 7 . The C-1 (0 to 95 percent distillation between 175°C and 246°C) and A-2 (0 to 95 percent distillation between 160°C and 255°C) fuels boil over a much wider range of temperatures 7 .…”

Section: Figure 2 A-2 Data Collection Rate Data Collection Rate Versupporting

confidence: 69%

Spray Characteristics and Flame Structure of Jet A and Alternative Jet Fuels

Mayhew

Mitsingas

McGann

et al. 2017

55th AIAA Aerospace Sciences Meeting

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A 2D phase Doppler anemometer is used to characterize alternative jet fuel droplets and compare them to Jet A fuel droplets in the National Jet Fuel Combustion Program referee single cup combustor near lean blowout. The two alternative jet fuels selected were chosen for their unusual properties: one with low cetane number and one with a flat boiling curve. Measurements are made on all three fuels at steady-state combustion at a pressure of 30 psia, swirler pressure drop of 3 percent, and a global equivalence ratio of 0.096. The results show differences in the droplet diameter distributions of the different fuels. This is particularly prominent in the flat boiling curve fuel, which has a Sauter mean diameter between 12 and 37 microns larger than the corresponding points for the other two fuels. OH* chemiluminescence imaging, conducted at 20kHz, is used to compare flame structures between the fuels as well as to correlate spray characteristics to flame location. The averaged OH* images show significant differences between the flame structures of the three fuels. The results of the study motivate further investigation into the correlation between alternative jet fuel spray characteristics and flame behavior for use in evaluating and predicting alternative jet fuel performance. Nomenclature φ = global equivalence ratio LBO = lean blowout PDPA = phase Doppler particle analyzer PDA = phase Doppler anemometry SMD = Sauter mean diameter I. IntroductionLIMATE change mitigation, economic concerns, and national energy security have motivated the research, development, and deployment of alternative jet fuels. It is desired for both military and commercial applications

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Section: Figure 2 A-2 Data Collection Rate Data Collection Rate Versupporting

confidence: 69%

Spray Characteristics and Flame Structure of Jet A and Alternative Jet Fuels

Mayhew

Mitsingas

McGann

et al. 2017

55th AIAA Aerospace Sciences Meeting

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“…The physical conditions were prescribed based on an estimated fuel temperature at 298K as this was an approximation to the water-cooled jacket temperature in the experiments. Reported properties for CAT A-2 12 are as follows, density = 795 / 3 , viscosity = 1.12 • , and surface tension = 24.7 / . The CAT C-3 12 properties reported are density = 800 / 3 , viscosity = 1.8…”

Section: Resultsmentioning

confidence: 99%

“…Reported properties for CAT A-2 12 are as follows, density = 795 / 3 , viscosity = 1.12 • , and surface tension = 24.7 / . The CAT C-3 12 properties reported are density = 800 / 3 , viscosity = 1.8…”

Section: Resultsmentioning

confidence: 99%

Numerical Investigation of Liquid Jet Breakup and Droplet Statistics with Comparison to X-ray Radiography

Bravo¹,

Kim²,

Ham³

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

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In direct injection engines, the jet primary and secondary breakup processes have a significant influence on the fuel/air mixture formation and drop-size distribution directly affecting the fuel conversion efficiency and combustion characteristics. In this work the disintegration process of turbulent liquid jets from a realistic diesel injector issuing into a still environment is investigated numerically using a coupled liquid/gas interface capturing technique and a high-fidelity DNS/LES approach. This study is aimed at assessing the influence of NJFCP aviation jet fuel mixtures on the disintegration and droplet-size spray characteristics at simulated diesel operating conditions. For this purpose, an unstructured unsplit Volume-of-Fluid method is employed in conjunction with a realistic diesel injector geometry to simulate the pulsed jet disintegration and breakup process. Flow and droplet PDF statistics are extracted to demonstrate the impact of physical properties (A2, C3 fuel) on the mixing behavior and droplet distribution. The simulations are compared against X-ray radiography volume fraction measurements from Argonne National Laboratory and also serve as numerical benchmarks for calibration of lower fidelity models. NomenclatureAccronyms VOF = Volume of Fluids LES = Large Eddy Simulation DNS = Direct Numerical Simulation PDF = Probability Density Function ROI = Rate of Injection Re = Reynolds number We = Weber number Oh = Ohnesorge number NJFCP = National Jet Fuel Combustion Program _________________________________ 1 Research Engineer, Vehicle Technoloy Directorate, APG, MD, AIAA Member.

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“…These high volume and cost tests focus on the upper and lower stability limits, or Figures-of-Merit (FOMs), of a gas turbine combustor under extreme conditions. 6,39 The lower stability limit of a gas turbine engine, lean blowout (LBO), is approached when a system can no longer sustain combustion. In this event, power and propulsion to the aircraft from the engine stops and is a long studied safety concern.…”

Section: ■ Introductionmentioning

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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An Overview of the National Jet Fuels Combustion Program

Cited by 33 publications

References 20 publications

Spray Characteristics and Flame Structure of Jet A and Alternative Jet Fuels

Spray Characteristics and Flame Structure of Jet A and Alternative Jet Fuels

Numerical Investigation of Liquid Jet Breakup and Droplet Statistics with Comparison to X-ray Radiography

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

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