FEM Approximation of Internal Combustion Chambers for Knock Investigations

Carstens-Behrens, S.; Urlaub, Mark; Böhme, J.F.; Förster, Jürgen; Raichle, Franz

doi:10.4271/2002-01-0237

Cited by 16 publications

(5 citation statements)

References 3 publications

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“…2. The frequencies of the oscillation is determined by the geometry of the combustion chamber [6]. For the SVC engine in particular, the fundamental frequency is approximately 8 kHz.…”

Section: The Standard Knock Model and Weak Knockmentioning

confidence: 99%

“…6 indicate that it is possible to lower the threshold significantly without risking false alarm. Figure 12 shows the relation between G knock and rko for three different thresholds, where h 5 400610 6 is the threshold that is used in the rest of the figures. These plots show that the bended curve segments in the beginning and end of the curves depend on the threshold, as well as the slope of the middle part of the curve.…”

Section: Knock Intensity and Rate Of Occurrencementioning

confidence: 99%

See 1 more Smart Citation

Weak knock characterization and detection for knock control

Nilsson

Frisk

Nielsen

2009

Proceedings of the Institution of Mechanical Engineers, Part D:

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Knock is a fundamental phenomenon in combustion engines, and knock control is central in any engine management system. Better understanding of knock, and weak knock in particular, is considered from two main aspects: knock detection and knock characterization. The aim of knock detectors is both to detect knock and to estimate the crank angle at knock onset. Focusing on weaker knock than before, it is shown that knock detectors and algorithms have to take into account other characteristics of knock traces than the standard model. It is shown that the best-performing knock detector of those investigated is one that supervises changes in signal variance, except for low signal-to-noise ratios where it is advantageous to use also the oscillation frequency. Regarding characterization, an important result is that in a wide range of intensities there is an almost linear dependence between the logarithmic normalized knock energy and the rate of cycles with knock. This means for example that a knock controller can use feedback on the rate of cycles with knock instead of knock intensity and vice versa; both can in combination with better detection provide possibilities for smoother and more anticipatory control schemes.

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“…2. The frequencies of the oscillation is determined by the geometry of the combustion chamber [6]. For the SVC engine in particular, the fundamental frequency is approximately 8 kHz.…”

Section: The Standard Knock Model and Weak Knockmentioning

confidence: 99%

Section: Knock Intensity and Rate Of Occurrencementioning

confidence: 99%

Weak knock characterization and detection for knock control

Nilsson

Frisk

Nielsen

2009

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Wavelet pattern matching was applied to compare actual and reference signals. Carstens-Behrens [254] of Ruhr University Bochum, together with collaborators at Bosch, performed timefrequency analysis using the Wigner-Ville transform and compared this to Finite Element Method (FEM) acoustic mode calculations of a pent-roof combustion chamber for various piston heights, as shown in Figure 37. Noubari and Dumont [255] of the University of Tehran and the University of British Columbia, respectively, employed wavelet methods to reduce both white and colored noise in accelerometer signals.…”

Section: The 2000s: Optical Measurements In Engine Development and De...mentioning

confidence: 99%

“…[249]. © SAE International FIGURE 37 First ten acoustic modes for pent-roof combustion chamber as calculated by Carstens-Behrens et al [254].…”

Section: The 2000s: Optical Measurements In Engine Development and De...mentioning

confidence: 99%

Knock: A Century of Research

Corrigan¹,

Fontanesi²

2021

SAE Int. J. Engines

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Knock is one of the main limitations on increasing spark-ignition (SI) engine efficiency. This has been known for at least 100 years, and it is still the case today. Knock occurs when conditions ahead of the flame front in an SI engine result in one or more autoignition events in the end gas. The autoignition reaction rate is typically much higher than that of the flame-front propagation. This may lead to the creation of pressure waves in the combustion chamber and, hence, an undesirable noise that gives knock its name. The resulting increased mechanical and thermal loading on engine components may eventually lead to engine failure. Reducing the compression ratio lowers end-gas temperatures and pressures, reducing end-gas reactivity and, hence, mitigating knock. However, this has a detrimental effect on engine efficiency.Automotive companies must significantly reduce their fleet carbon dioxide (CO 2 ) values in the coming years to meet targets resulting from the 2015 Paris Agreement. One path towards meeting these is through partial or full electrification of the powertrain. However, the vast majority of automobiles in the near future will still feature a gasoline-fueled SI engine; hence, improvements in combustion engine efficiency remain fundamental.As knock has been a key limitation for so long, there is a huge amount of literature on the subject. A number of reviews on knock have already been published, including in recent years. These generally concentrate on current understanding and status. The present work, in contrast, aims to track the progress of research on knock from the 1920s right through to the present day. It is hoped that this can be a useful reference for new and existing researchers of the subject and give further weight to occasionally neglected historical activity, which can still provide important insights today.

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“…The frequency of the oscillation is determined by the geometry of the combustion chamber, where the fundamental oscillatory mode is a wave travelling from one side of the combustion chamber to the opposite side (Carstens-Behrens et al, 2002). Using a well tuned high pass filter, the oscillating knock signal can then be detected.…”

Section: The Knock Signaturementioning

confidence: 99%

Detecting Knock in Spark Ignited Engines

Nilsson

Frisk

2005

IFAC Proceedings Volumes

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In this paper we consider signal processing algorithms for detecting knock, i.e. auto-ignition of unburned fuel, in spark-ignited engines. To operate an engine with optimal efficiency, there is a need to operate close to the knock limit. This motivates the need for efficient knock detection algorithms that not only indicates knock, but also gives estimates on knock timing and size. The proposed detection algorithms are based on either incylinder pressure or ion current and both off-line and on-line methods are developed. The methods are tested on measured data, analysed, and compared with respect to detection performance, knock timing estimation accuracy, and robustness against model uncertainties.

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FEM Approximation of Internal Combustion Chambers for Knock Investigations

Cited by 16 publications

References 3 publications

Weak knock characterization and detection for knock control

Weak knock characterization and detection for knock control

Knock: A Century of Research

Detecting Knock in Spark Ignited Engines

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