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The phenomenon of knock is an abnormal combustion occurring in spark-ignition (SI) engines and forms a barrier that prevents an increase in thermal efficiency while simultaneously reducing CO2 emissions. Since knocking combustion is highly stochastic, a cyclic analysis of in-cylinder pressure is necessary. In this study we propose an approach for efficient and robust detection and identification of knocking combustion in three different internal combustion engines. The proposed methodology includes a signal processing technique, called continuous wavelet transformation (CWT), which provides a simultaneous analysis of the in-cylinder pressure traces in the time and frequency domains with coefficients. These coefficients serve as input for a convolutional neural network (CNN) which extracts distinctive features and performs an image recognition task in order to distinguish between non-knock and knock. The results revealed the following: (i) The CWT delivered a stable and effective feature space with the coefficients that represents the unique time-frequency pattern of each individual in-cylinder pressure cycle; (ii) the proposed approach was superior to the state-of-the-art threshold value exceeded (TVE) method with a maximum amplitude pressure oscillation (MAPO) criterion improving the overall accuracy by 6.15 percentage points (up to 92.62%); and (iii) The CWT + CNN method does not require calibrating threshold values for different engines or operating conditions as long as enough and diverse data is used to train the neural network.
Achilles Kefalas; Andreas B. Ofner; Gerhard Pirker; Stefan Posch; Bernhard C. Geiger; Andreas Wimmer. Detection of Knocking Combustion Using the Continuous Wavelet Transformation and a Convolutional Neural Network. Energies 2021, 14, 439 .
AMA StyleAchilles Kefalas, Andreas B. Ofner, Gerhard Pirker, Stefan Posch, Bernhard C. Geiger, Andreas Wimmer. Detection of Knocking Combustion Using the Continuous Wavelet Transformation and a Convolutional Neural Network. Energies. 2021; 14 (2):439.
Chicago/Turabian StyleAchilles Kefalas; Andreas B. Ofner; Gerhard Pirker; Stefan Posch; Bernhard C. Geiger; Andreas Wimmer. 2021. "Detection of Knocking Combustion Using the Continuous Wavelet Transformation and a Convolutional Neural Network." Energies 14, no. 2: 439.
Large gas engines currently play an important role in decentralized energy supply concepts worldwide and will continue to do so in the future. Over the years, a broad spectrum of combustion concepts has been developed for gas engines. Some of these concepts make use of external mixture formation with port injection gas valves while others employ internal mixture formation with high-pressure direct injection gas valves.
Constantin Kiesling; Anton Tilz; Andreas Nickl; Hubert Winter; Gerhard Pirker; Andreas Wimmer. Evaluation of Gas Injection Valves for Large Engines by Means of Spray Momentum Measurement. Proceedings 2018, 481 -497.
AMA StyleConstantin Kiesling, Anton Tilz, Andreas Nickl, Hubert Winter, Gerhard Pirker, Andreas Wimmer. Evaluation of Gas Injection Valves for Large Engines by Means of Spray Momentum Measurement. Proceedings. 2018; ():481-497.
Chicago/Turabian StyleConstantin Kiesling; Anton Tilz; Andreas Nickl; Hubert Winter; Gerhard Pirker; Andreas Wimmer. 2018. "Evaluation of Gas Injection Valves for Large Engines by Means of Spray Momentum Measurement." Proceedings , no. : 481-497.
Die Analyse des Zylinderdruckverlaufes ist trotz der Weiterentwicklung optischer Messverfahren bei der heutigen Entwicklung von Verbrennungsmotoren nicht wegzudenken. Zum einen ist der Zylinderdruckverlauf die wichtigste Größe zur Erkennung von klopfender Verbrennung online am Prüfstand und zum anderen können aus der thermodynamischen Analyse des Drucksignals wichtige Erkenntnisse hinsichtlich der Verbrennung (Entflammungsdauer, Zündverzug, Heiz‑ und Brennverlauf) sowie der sogenannten Verlustteilung gewonnen werden. Zudem gibt der Druckverlauf Aufschluss über die Einhaltung des vorgegebenen Spitzendruckes, die indizierte Arbeit sowie über das Ladungswechselverhalten des Motors (Füllung) und das Restgas im Brennraum.
Rüdiger Teichmann; Andreas Wimmer. Druckverlaufsanalyse. Grundlagen Verbrennungsmotoren 2018, 901 -911.
AMA StyleRüdiger Teichmann, Andreas Wimmer. Druckverlaufsanalyse. Grundlagen Verbrennungsmotoren. 2018; ():901-911.
Chicago/Turabian StyleRüdiger Teichmann; Andreas Wimmer. 2018. "Druckverlaufsanalyse." Grundlagen Verbrennungsmotoren , no. : 901-911.
Der Verbrennungsmotor bezieht seine Energie aus der Umsetzung der chemischen Energie in Wärme. Diesen Vorgang zu verstehen, so effizient und schadstoffarm wie möglich zu gestalten ist das Ziel der Verbrennungsdiagnostik. Während die Messung des Verbrennungsdrucks (Abb. 32.1 oben) so alt wie der Verbrennungsmotor selbst ist und einen globalen Wert aus dem Brennraum repräsentiert, bestand immer der Wunsch zusätzliche Informationen oder auch räumliche Information von der Verbrennung für eine Optimierung zur Verfügung zu haben. Dafür hat sich die optische Messtechnik (Abb. 32.1 unten) durchgesetzt. Neben dem Einsatz in Forschungslabors oder in der Vorentwicklung kommt diese Technik gerade in den letzten Jahren ob ihrer Robustheit und einfachen Applizierbarkeit auch ergänzend in der Serienentwicklung zum Einsatz. Der Messung von Verbrennungswerten schließt sich zum einen eine Analyse während der Messung und oftmals eine aufwendige und tiefgründige Analyse nach der Messung an (Abb. 32.1 rechts).
Rüdiger Teichmann; Andreas Wimmer. Druckindizierung. Grundlagen Verbrennungsmotoren 2018, 851 -900.
AMA StyleRüdiger Teichmann, Andreas Wimmer. Druckindizierung. Grundlagen Verbrennungsmotoren. 2018; ():851-900.
Chicago/Turabian StyleRüdiger Teichmann; Andreas Wimmer. 2018. "Druckindizierung." Grundlagen Verbrennungsmotoren , no. : 851-900.
Until several years ago, large engines were primarily developed for single fuel operation, which has resulted in the availability of optimized gas and diesel combustion concepts. Today large engines are subject to new requirements that go beyond merely enhancing existing concepts. In a wide variety of areas of application, the focus is not only on attaining the highest efficiency with the lowest possible emissions but also on attaining the greatest possible flexibility in terms of fuel.
Markus Krenn; Christoph Redtenbacher; Gerhard Pirker; Andreas Wimmer. A new approach for combustion modeling of large dual-fuel engines. Proceedings 2018, 155 -173.
AMA StyleMarkus Krenn, Christoph Redtenbacher, Gerhard Pirker, Andreas Wimmer. A new approach for combustion modeling of large dual-fuel engines. Proceedings. 2018; ():155-173.
Chicago/Turabian StyleMarkus Krenn; Christoph Redtenbacher; Gerhard Pirker; Andreas Wimmer. 2018. "A new approach for combustion modeling of large dual-fuel engines." Proceedings , no. : 155-173.
This paper focuses on improving the 3D-Computational Fluid Dynamics (CFD) modeling of diesel ignited gas engines, with an emphasis on injection and combustion modeling. The challenges of modeling are stated and possible solutions are provided. A specific approach for modeling injection is proposed that improves the modeling of the ballistic region of the needle lift. Experimental results from an inert spray chamber are used for model validation. Two-stage ignition methods are described along with improvements in ignition delay modeling of the diesel ignited gas engine. The improved models are used in the Extended Coherent Flame Model with the 3 Zones approach (ECFM-3Z). The predictive capability of the models is investigated using data from single cylinder engine (SCE) tests conducted at the Large Engines Competence Center (LEC). The results are discussed and further steps for development are identified.
Lucas Eder; Marko Ban; Gerhard Pirker; Milan Vujanovic; Peter Priesching; Andreas Wimmer. Development and Validation of 3D-CFD Injection and Combustion Models for Dual Fuel Combustion in Diesel Ignited Large Gas Engines. Energies 2018, 11, 643 .
AMA StyleLucas Eder, Marko Ban, Gerhard Pirker, Milan Vujanovic, Peter Priesching, Andreas Wimmer. Development and Validation of 3D-CFD Injection and Combustion Models for Dual Fuel Combustion in Diesel Ignited Large Gas Engines. Energies. 2018; 11 (3):643.
Chicago/Turabian StyleLucas Eder; Marko Ban; Gerhard Pirker; Milan Vujanovic; Peter Priesching; Andreas Wimmer. 2018. "Development and Validation of 3D-CFD Injection and Combustion Models for Dual Fuel Combustion in Diesel Ignited Large Gas Engines." Energies 11, no. 3: 643.
The aim of this paper is to identify and investigate the potential and limitations of diesel–gas combustion concepts for high speed large engines operated in gas mode with very small amounts of pilot fuel (
Christoph Redtenbacher; Constantin Kiesling; Maximilian Malin; Andreas Wimmer; José V. Pastor; Mattia Pinotti. Potential and Limitations of Dual Fuel Operation of High Speed Large Engines. Journal of Energy Resources Technology 2017, 140, 032205 .
AMA StyleChristoph Redtenbacher, Constantin Kiesling, Maximilian Malin, Andreas Wimmer, José V. Pastor, Mattia Pinotti. Potential and Limitations of Dual Fuel Operation of High Speed Large Engines. Journal of Energy Resources Technology. 2017; 140 (3):032205.
Chicago/Turabian StyleChristoph Redtenbacher; Constantin Kiesling; Maximilian Malin; Andreas Wimmer; José V. Pastor; Mattia Pinotti. 2017. "Potential and Limitations of Dual Fuel Operation of High Speed Large Engines." Journal of Energy Resources Technology 140, no. 3: 032205.
A controversial debate is currently going on in the scientific literature regarding the future importance of diesel-gas dual fuel concepts for large engines. Arguments in their favor are advantages such as the redundancy of the propulsion system when one fuel source fails, the flexibility to adapt the choice of fuel to current prices and also lower emissions in gas operation mode than with a pure diesel engine. Despite gradual advances in dual fuel technology, significant disadvantages in efficiency and combustion stability still exist in comparison to monovalent engines. To increase market acceptance of diesel-gas engines, the focus of development must be to increase efficiency and improve the robustness of combustion concepts.
Maximilian Malin; Constantin Kiesling; Christoph Redtenbacher; Andreas Wimmer. Einfluss der Diesel-Piloteinspritzung auf die Verbrennung in Diesel-Gas Dual Fuel Motoren. Proceedings 2017, 491 -514.
AMA StyleMaximilian Malin, Constantin Kiesling, Christoph Redtenbacher, Andreas Wimmer. Einfluss der Diesel-Piloteinspritzung auf die Verbrennung in Diesel-Gas Dual Fuel Motoren. Proceedings. 2017; ():491-514.
Chicago/Turabian StyleMaximilian Malin; Constantin Kiesling; Christoph Redtenbacher; Andreas Wimmer. 2017. "Einfluss der Diesel-Piloteinspritzung auf die Verbrennung in Diesel-Gas Dual Fuel Motoren." Proceedings , no. : 491-514.
Interest is growing in using fully flexible diesel-gas dual fuel engines for power generation and propulsion on land and sea. Benefits such as the flexibility to adapt the type of fuel to the market situation, fail-safe operation and lower NOx emissions than diesel engines are convincing arguments for engine operators. However, diesel-gas engine concepts still suffer from lower efficiency than state-of-the-art monovalent diesel engines and spark ignited gas engines when operated in the corresponding fuel mode. To meet stringent NOx emission legislation, high diesel substitution rates are necessary, which in turn often lead to poor combustion stability. Especially with these small diesel fractions, the challenge remains to ensure stable ignition, fast combustion of the air-fuel mixture and low hydrocarbon emissions. The aim of this paper is to identify and investigate the potential and limitations of diesel-gas combustion concepts for high speed large engines operated in gas mode with very small amounts of pilot fuel (< 5 % diesel fraction1). Experimental tests were carried out on a flexible single cylinder research engine (swept volume approximately 6 1) equipped with a common rail system. Various engine configurations and operating parameters were varied and the effects on the combustion process were analyzed. The results presented in this paper include a comparison of the performance of the investigated dual fuel concept to those of a state-of-the-art monovalent gas engine and a state-of-the-art monovalent diesel engine. Evaluation reveals that certain limiting factors exist that prevent the dual fuel engine from performing as well as the superior gas engine. On the other hand, the potential is already present for the dual fuel concept to compete with the diesel engine. Since the injection of pilot fuel is of major importance for flame initialization and thus for the main combustion event of the dual fuel engine, optical investigations in a spray box, measurements of injection rates and 3D-CFD simulation were conducted to obtain even more detailed insight into these processes. A study on the influence of the diesel fraction shows that diminishing the diesel fraction from 3 % to lower values has a significant impact on engine performance because of the effects of such a reduction on injection, ignition delay and initial flame formation. An investigation of the influence of the injection timing reveals that with diesel fractions of ≤ 1.5 %, the well-known relationship between the injection timing and combustion phasing of conventional engine concepts is no longer valid. The presented results illustrate which operating strategy is beneficial for engine performance in terms of low NOx emissions and high efficiency. Moreover, potential measures can be derived which allow for further optimization of the diesel-gas combustion process.
Christoph Redtenbacher; Constantin Kiesling; Maximilian Malin; Andreas Wimmer; José V. Pastor; Mattia Pinotti. Potential and Limitations of Dual Fuel Operation of High Speed Large Engines. ASME 2016 Internal Combustion Engine Division Fall Technical Conference 2016, 1 .
AMA StyleChristoph Redtenbacher, Constantin Kiesling, Maximilian Malin, Andreas Wimmer, José V. Pastor, Mattia Pinotti. Potential and Limitations of Dual Fuel Operation of High Speed Large Engines. ASME 2016 Internal Combustion Engine Division Fall Technical Conference. 2016; ():1.
Chicago/Turabian StyleChristoph Redtenbacher; Constantin Kiesling; Maximilian Malin; Andreas Wimmer; José V. Pastor; Mattia Pinotti. 2016. "Potential and Limitations of Dual Fuel Operation of High Speed Large Engines." ASME 2016 Internal Combustion Engine Division Fall Technical Conference , no. : 1.
Pressure measurement is as old as the development of internal combustion engines themselves. A confirmation of this can be seen in Fig. 3.1, which shows a cylinder pressure profile recorded with a mechanical indicator by August Nikolaus SI on 18th of May, 1876. This moment in time is often considered to be the starting point of the historical development of pressure indication, see Hohenberg (1994). After over 135 years of development, this measurement technique has become universally established and is used as the standard measurement method on most engine test benches, Frommelt et al.(2008).
Rüdiger Teichmann; Andreas Wimmer; Christian Schwarz; Ernst Winklhofer. Combustion Diagnostics. Combustion Engines Development 2011, 39 -117.
AMA StyleRüdiger Teichmann, Andreas Wimmer, Christian Schwarz, Ernst Winklhofer. Combustion Diagnostics. Combustion Engines Development. 2011; ():39-117.
Chicago/Turabian StyleRüdiger Teichmann; Andreas Wimmer; Christian Schwarz; Ernst Winklhofer. 2011. "Combustion Diagnostics." Combustion Engines Development , no. : 39-117.