Spray Measurements at Elevated Pressures and Temperatures Using Phase Doppler Anemometry

Bokhart, Andrew J.; Shin, Dongyung; Gejji, Rohan; Sojka, Paul E.; Gore, Jay P.; Lucht, Robert P.; Naik, Sameer V.; Buschhagen, Timo

doi:10.2514/6.2017-0828

Cited by 15 publications

(4 citation statements)

References 5 publications

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“…Consistent with the findings of Burger et al [12], blowoff correlated best with fuel vaporization processes at 300 K. At this lower air temperature, the low T90 fuels were the most blowoff resistant and the high T90 fuels blew out the easiest. As the atomization characteristics of these fuels would presumably influence lean blowout boundaries, several studies [27][28][29][30], which were coordinated with the present work to use a similar pressure atomizing, filming type fuel injector, have also measured the mean droplet sizes and distributions of the tested fuels. These droplet sizing measurements found no correlation between fuel physical properties and droplet sizes for the tested pressure atomizer injector.…”

Section: Introductionmentioning

confidence: 97%

Near-lean blowoff dynamics in a liquid fueled combustor

Rock

Emerson

Seitzman

et al. 2020

Combustion and Flame

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This paper describes an analysis of the near-lean blow off(LBO) dynamics of spray flames, including the influence of fuel composition upon these dynamics. It is motivated by the fact that, while reasonable correlations exist for predicting blowoffconditions, the fundamental reasons for why flames supported by flow recirculation actually blow offare not well understood. Prior work on gaseous systems has shown that the blowoffevent is a culmination of several intermediate processes, initiating with local extinction of reactions ("stage 1"), followed by large scale changes in flame and flow dynamics ("stage 2"), finally leading to blowoff. In this study, near-LBO dynamics were characterized for ten liquid fuels with widely varying kinetic and physical properties. Results were compared at two air inlet temperatures, 450 and 300 K, as this influences the relative importance of physical and kinetic properties in controlling LBO. Extinction, re-ignition, and recovery of the flame are evident from these data, and grow in frequency as blowoffis approached. Results show that after a near-blowoffevent, the flame can move upstream at velocities much faster than the flow velocity, corresponding to re-ignition. Nonetheless, the majority of the flame recovery events appear to be associated with convection of hot products back upstream, not re-ignition. In contrast, downstream motion of the flame faster than the flow, which would correspond to bulk flame extinction, was never observed. This indicates that "extinction events"actually correspond to convection of the flame downstream by the flow when it loses its stabilization point. The dependence of the equivalence ratio when these events appear, their frequency, and event duration were quantified as a function of fuel composition and air inlet temperature. For example, the data shows a higher percentage of recovery from near-blowoffevents through re-ignition for high DCN fuels at the 450 K air temperature condition. These extinction/re-ignition results suggest that high DCN fuels are harder to blow offthan low DCN fuels through two mechanisms: (1) by delaying the onset of LBO precursor events, and (2) because they are able to recover from these precursor events through re-ignition more often.

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Section: Introductionmentioning

confidence: 97%

Near-lean blowoff dynamics in a liquid fueled combustor

Rock

Emerson

Seitzman

et al. 2020

Combustion and Flame

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“…To the authors' best knowledge, only a handful of studies have been reported on the atomization of NG-SPK jet fuel at elevated operating conditions relevant to aviation gas turbine combustors. Under the "National Jet Fuels Combustion Program (NJFCP)" [16], Bokhart et al [17] examined the atomization performance of alternative jet fuels using a simplex atomizer in a constant pressure experimental facility simulating the lean-blowout scenario. The ambient conditions inside the facility were maintained at 204 kPa and 394 K, and the fuel was delivered at 322 K. The nozzle pressure differential was noted to impact the droplet size substantially.…”

Section: Introductionmentioning

confidence: 99%

“…Mayhew et al [18] performed a similar study on NJFCP fuels in a combustion environment and reported that the fuel volatilization properties influenced the droplet sizes for the conditions studied. In both studies [17,18], spray measurements were conducted at constant pressure (ambient) and temperature (ambient, fuel).…”

Section: Introductionmentioning

confidence: 99%

Influence of Fuel Characteristics on the Alternative Jet Fuel Atomization at Non-Reacting Conditions

Kannaiyan¹,

Sadr

2023

Preprint

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“…The approval of SAF is arduous. Novel fuels are subjected to up to 4 tiers of testing, 2 research reports, and 3 balloting junctions involving dozens of stakeholders under ASTM D4054. , To help address this, significant efforts have been made via The National Jet Fuels Combustion Program (NJFCP) to lower the barriers of cost and fuel volume for novel SAF approvals and streamline the certification process. − Under the NJFCP, many conventional and alternative fuels were tested, targeting the experiments within the ASTM D4054 process that requires the largest volumes of fuel and greatest overall cost. 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. , …”

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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Spray Measurements at Elevated Pressures and Temperatures Using Phase Doppler Anemometry

Cited by 15 publications

References 5 publications

Near-lean blowoff dynamics in a liquid fueled combustor

Near-lean blowoff dynamics in a liquid fueled combustor

Influence of Fuel Characteristics on the Alternative Jet Fuel Atomization at Non-Reacting Conditions

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

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