Knock criteria for aviation diesel engines

Meininger, Rik D.; Kweon, Chol-Bum; Szedlmayer, Michael T.; Dang, Khanh; Jackson, N.; Lindsey, Christopher A.; Gibson, Joseph A.; Armstrong, Ross

doi:10.1177/1468087416669882

Cited by 31 publications

(11 citation statements)

References 10 publications

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“…Different metrics exist to quantify combustion noise, from the HCCI-suited ringing intensity (RI; MW/m 2 ) indicating the power flux delivered by the pressure waves, 29 to the Noise (dB) indicating the perceived noise outside of the engine (more indicated for conventional engine modes). 30 Given that the RI metric has been specifically developed for HCCI engines and is still being used today (see for example), 31,32 this metric uncertainty will be developed here-under. However, the uncertainty related to any other metric can be obtained following the general methodology developed in this article.…”

Section: Results: Uncertainties On the Physical Quantities Requiring mentioning

confidence: 99%

Uncertainty quantification from raw measurements to post-processed data: A general methodology and its application to a homogeneous-charge compression–ignition engine

Pochet

Jeanmart

Contino

2019

International Journal of Engine Research

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Internal combustion engines have been improved for many decades. Yet, complex phenomena are now resorted to, for which any optimum might be unstable: noise, low-temperature heat release timing, stratification, pollutant sweet spots, and so on. In order to make reliable statements on an improvement, one must specify the uncertainty related to it. Still, uncertainty quantification is generally missing in the piston engine experimental literature. Therefore, we detailed a mathematical methodology to obtain any engine parameter uncertainty and then used it to derive the uncertainty expressions of the physical quantities of the most generic homogeneous-charge compression–ignition research engine (mass-flow-induced mixture with [Formula: see text] fuel). We then applied those expressions on an existing hydrogen homogeneous-charge compression–ignition test bench. This includes the uncertainty propagation chain from sensor specifications, user calibrations, intake control, in-cylinder processes, and post-processing techniques. Directly measured physical quantities have uncertainties of around 1%, depending on the sensor quality (e.g. pressure, volume), but indirectly measured quantities relying on modelled parameters have uncertainties higher than 5% (e.g. wall heat losses, in-cylinder temperature, gross heat release, pressure rise rate). Other findings that such an analysis can bring relate, for example, to the physical quantities driving the uncertainty and to the ones that can be neglected. In the case of the homogeneous-charge compression–ignition engine considered, the effects of blow-by, bottle purity and air moisture content were found negligible; the post-processing for effective compression ratio, effective in-cylinder temperature, and top dead centre offset were found essential; and the pressure and volume uncertainties were found to be the main drivers to a large extent. The obtained numeric values serve the general purpose of alerting the experimenter on uncertainty order of magnitudes. The developed methodology shall be used and adapted by the experimenter willing to study the uncertainty propagation in their setup or willing to assess the adequacy of a sensor performance.

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Section: Results: Uncertainties On the Physical Quantities Requiring mentioning

confidence: 99%

Uncertainty quantification from raw measurements to post-processed data: A general methodology and its application to a homogeneous-charge compression–ignition engine

Pochet

Jeanmart

Contino

2019

International Journal of Engine Research

View full text Add to dashboard Cite

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“…Further increasing FIP up to 60 MPa, knock intensity is enhanced under the both two scenarios. The peak of pressure oscillations reach ∆P max = 7.98 MPa (P c = 2.14 MPa) and ∆P max = 5.85 MPa (P c = 4.13 MPa), which are manifested superknock level according to knock criteria aforementioned [4]. Therefore, for the given compressed pressure, diesel knock becomes prevalent with the increase of fuel injection pressure.…”

Section: Effects Of Fuel Injection Pressurementioning

confidence: 95%

“…Consequently, severe diesel knock with destructive pressure oscillation is likely to occur in heavy-duty diesel engines under low-speed and high-load conditions. When diesel knock occurs at high altitude regions, the amplitude of pressure oscillation can reach several dozens of atmosphere, which results in cylinder head erosion and piston crown breakdown [4]. However, the detailed mechanism for such an abnormal combustion still remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Diesel Knock for High-Altitude Heavy-Duty Engines Using Optical Rapid Compression Machines

et al. 2020

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In high altitude regions, affected by the low-pressure and low-temperature atmosphere, diesel knock is likely to be encountered in heavy-duty engines operating at low-speed and high-load conditions. Pressure oscillations during diesel knock are commonly captured by pressure transducers, while there is a lack of direct evidence and visualization images, such that its fundamental formation mechanism is still unclear. In this study, optical experiments on diesel knock with destructive pressure oscillations were investigated in an optical rapid compression machine. High-speed direct photography and simultaneous pressure acquisition were synchronically performed, and different injection pressures and ambient pressures were considered. The results show that for the given ambient temperature and pressure, diesel knock becomes prevalent at higher injection pressures where fuel spray impingement becomes enhanced. Higher ambient pressure can reduce the tendency to diesel knock under critical conditions. For the given injection pressure satisfying knocking combustion, knock intensity is decreased as ambient pressure is increased. Further analysis of visualization images shows diesel knock is closely associated with the prolonged ignition delay time due to diesel spray impingement. High-frequency pressure oscillation is caused by the propagation of supersonic reaction-front originating from the second-stage autoignition of mixture. In addition, the oscillation frequencies are obtained through the fast Fourier transform (FFT) analysis.

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“…Under low-speed and high-load conditions, severe diesel knock with destructive pressure oscillation is likely to occur in heavy-duty diesel engines. When diesel knock occurs at high altitude regions, its intensity can reach several dozens of atmosphere, which results in cylinder head erosion and piston crown breakdown [4]. However, the detailed mechanism for such an abnormal combustion still remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Output Temperature Predictions of the Geothermal Heat Pump System Using an Improved Grey Prediction Model

Wang¹,

Wei²,

Pan³

et al. 2022

Advances in Energy Research

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In high altitude regions, affected by low pressure and low temperature atmosphere, diesel knock is likely to be encountered in heavy-duty engines operating at low-speed and high-load conditions. Diesel knock is commonly measured through pressure transducers, while there is lack of direct evidence and visualization images, such that its fundamental formation mechanism is still unclear. In this study, optical experiments on the severe diesel knock with destructive pressure oscillations were investigated in an optical rapid compression machine. High-speed direct photography and simultaneous pressure acquisition were synchronically performed, and different injection pressure and ambient pressure conditions were considered. The results show that for the given ambient temperature and pressure, diesel knock becomes prevalent at higher injection pressures where fuel spray impingement is enhanced. For the given injection pressure satisfying spray impingement, knock intensity is increased as ambient pressure is decreased. Further analysis on visualization images shows diesel spray impingement leads to longer ignition delay time, by which near-wall autoignition and supersonic reaction front propagation are induced. Consequently, three distinguishing stages can be observed during diesel knock, i.e. ignition delay, reaction front propagation, and pressure oscillation. Both spray impingement and fuel evaporation processes are considered as the main influencing factors.

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Knock criteria for aviation diesel engines

Cited by 31 publications

References 10 publications

Uncertainty quantification from raw measurements to post-processed data: A general methodology and its application to a homogeneous-charge compression–ignition engine

Uncertainty quantification from raw measurements to post-processed data: A general methodology and its application to a homogeneous-charge compression–ignition engine

Analysis of Diesel Knock for High-Altitude Heavy-Duty Engines Using Optical Rapid Compression Machines

Output Temperature Predictions of the Geothermal Heat Pump System Using an Improved Grey Prediction Model

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