<i>RUMBLE —</i> a deposit effect at high compression ratios

Felt, A. E.; Warren, James A.; Hall, C. A.

doi:10.4271/590018

Cited by 15 publications

(2 citation statements)

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“…The deviation between measured and calculated low-temperature IDTs ranged between a factor of 2 to 4. These experiments were carried out with various degrees and combinations of shock tube cleaning processes (e.g., turbopumped to 10 -5 Torr, rough-pumped to 10 -2 Torr, scrubbed with acetone, diaphragm pieces from 8 previous runs removed / left, etc.). No systematic effect of the cleaning procedure was observed on the results.…”

Section: Ignition Delay Time Measurementsmentioning

confidence: 99%

“…As these engineering systems have evolved with time, the factors that lead to preignition back then could be different to those observed nowadays [5]. Generally, preignition hypotheses revolve around the existence of hot surfaces [6] or hot particles [7,8,9] that can be the source of end-gas ignition during an engine cycle. The importance of understanding preignition lays on the negative effects that it can cause on engines, such as highpressure events identified as knock [10] or the more dramatic superknock [11], and the limitations it puts on designing modern downsized engines.…”

Section: Introductionmentioning

confidence: 99%

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Shock tube studies of ethanol preignition

Figueroa-Labastida

Badra

Elbaz

et al. 2018

Combustion and Flame

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CitationFigueroa-Labastida M, Badra J, Elbaz AM, Farooq A (2018) Shock tube studies of ethanol preignition. . Available: http://dx. AbstractUnderstanding premature ignition or preignition is of great importance as this phenomenon influences the design and operation of internal combustion engines. Preignition leading to super-knock restricts the efficiency of downsized boosted engines. To gain a fundamental understanding of preignition and how it affects an otherwise homogeneous ignition process, a shock tube may be used to decipher the influence of fuel chemical structure, temperature, pressure, equivalence ratio and bath gas on preignition. In a previous work by Javed et al.[1], ignition delay time measurements of nheptane showed significantly expedited reactivity compared to well-validated chemical kinetic models in the intermediate-temperature regime. In the current work, ethanol is chosen as a representative fuel that, unlike n-heptane, does not exhibit negative temperature coefficient (NTC) behaviour. Reactive mixtures containing 2.9% and 5% of ethanol at equivalence ratios of 0.5 and 1 were used for the measurement of ignition delay times behind reflected shock waves at 2 and 4 bar. Effect of bath gas was studied with mixtures containing either Ar or N2. In addition to conventional side-wall pressure and OH* measurements, a high-speed imaging setup was utilized to visualize the shock tube crosssection through a transparent quartz end-wall. The results suggest that preignition events are more likely to happen in mixtures containing higher ethanol concentration and that preignition energy release is more pronounced at lower temperatures. High-speed imaging shows that low-temperature ignition process is usually initiated from an individual hot spot that grows gradually, while hightemperatures ignition starts from many spots simultaneously which consume the reactive mixture almost homogeneously.

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Section: Ignition Delay Time Measurementsmentioning

confidence: 99%