Spray Characteristics of a Hybrid Airblast Pressure-Swirl Atomizer at Near Lean Blowout Conditions using Phase Doppler Anemometry

Bokhart, Andrew J.; Shin, Dong Ku; Rodrigues, Neil S.; Sojka, Paul E.; Gore, Jay P.; Lucht, Robert P.

doi:10.2514/6.2018-2187

Cited by 8 publications

(1 citation statement)

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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: 98%

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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