Development of advanced cylinder liner conformation concepts of internal combustion engines with numerical simulation methods

Publikation: Qualifikations-/Studienabschlussarbeit › Dissertation

Autoren

  • Ahmad Alshwawra

Organisationseinheiten

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Details

Titel in ÜbersetzungEntwicklung innovativer Konzepte für Zylinderlaufbuchsen von Verbrennungsmotoren mit numerischen Simulationsmethoden
OriginalspracheEnglisch
QualifikationDoktor der Ingenieurwissenschaften
Gradverleihende Hochschule
Betreut von
  • Friedrich Dinkelacker, Betreuer*in
Förderer
  • German-Jordanian University (GJU)
  • Bundesministerium für Wirtschaft und Energie (BMWi)
  • Hochschulbüro für ChancenVielfalt
Datum der Verleihung des Grades11 Juli 2023
ErscheinungsortHannover
PublikationsstatusVeröffentlicht - 2023

Abstract

Ein erhebliches Potenzial zur Verbesserung von Verbrennungsmotoren liegt in der verbesserten Kopplung von Kolbenringen und Zylinder Laufbuchsen (Piston Ring Cylinder Coupling, PRCL). Um die Konformität von PRCL zu verbessern und die Reibung zu verringern, wird in einem gefeuerter Betrieb eine möglichst kreisförmige Querschnittsform der Laufbuchse angestrebt. Je weiter sich der Querschnitt der Laufbuchse eines Kreises annähert, desto besser ist die Konformität. Um dies zu erreichen, muss der Motor im kalten Zustand eine nicht-kreisförmige Laufbuchse haben, die sich unter thermischen und mechanischen Belastungen des gefeuerten Motors kontrolliert verformt und dann eine Laufbuchse mit ideal kreisförmigem Querschnitt bildet. Darüber hinaus können weitere tribologische Verbesserungen erzielt werden, indem im gefeuerten Betrieb eine nicht-prismatische, kreisförmige Laufbuchse angestrebt wird. Diese kumulative Arbeit präsentiert numerische Untersuchungen für diese Hypothese und liefert quantitative Analysen, um die Vor- und Nachteile mit nicht-kreisförmigen Laufbuchsen aufzuzeigen. Darüber hinaus werden Richtlinien für das Design nicht-kreisförmiger Freiformlaufbuchsen dargelegt. Die Simulationsmodelle dieser Arbeit basieren auf der Finite-Elemente-Methode. Zwei physikalische Modelle wurden betrachtet: Eines für einen Serien-Gasmotor und ein zweites für einen Einzylinder-Forschungsmotor. Die Modelle wurden anhand experimenteller Daten validiert, woraufhin die lokalen Verformungen der Laufbuchsen simuliert wurden. Unter Anwendung der harmonische Analyse wurden die Deformationsordnungen für definierte Betriebspunkte untersucht. Darauf aufbauend wurden verschiedene Formen von nicht-kreisförmigen Laufbuchsen basierend auf dem Konzept des Reverse Engineering ausgelegt. Geometrische Indikatoren wurden definiert und in vergleichenden Analysen verwendet. Die Ergebnisse zeigen eine signifikante Verbesserung des geometrie-bedingten Verhaltens bei Verwendung von nicht-kreisförmigen Laufbuchsen. Eine speziell entwickelte Freiformlaufbuchse kann die Rundheit der Bohrung um 95 % und die Geradheit um 75 % verbessern. Das Konzept der führenden Deformationsordnungen ermöglicht eine signifikante Vereinfachung des Designs. Als Beispiel hierfür ist eine elliptische Konuslaufbuchse eine gute, jedoch einfachere Alternative, die eine Verbesserung der Rundheit um 85 % und der Geradheit der Laufbuchse um 65 % während des Betriebs aufweist. Die Freiformlaufbuchse ist empfindlich bezüglich der Motorenlast. Da bestimmte Deformationsordnungen jedoch unabhängig vom Betriebspunkt sind, können diese bei der Laufbuchsengestaltung besonders berücksichtigt werden. Die hier präsentierten Ergebnisse zeigen ein großes Potenzial zur tribologischen Verbesserung. Parallel stattfindende experimentelle Arbeiten zeigen eine signifikante Reduzierung der Reibungsverluste durch die Verwendung einer in dieser Arbeit entwickelten Laufbuchsen.

Zitieren

Development of advanced cylinder liner conformation concepts of internal combustion engines with numerical simulation methods. / Alshwawra, Ahmad.
Hannover, 2023. 89 S.

Publikation: Qualifikations-/Studienabschlussarbeit › Dissertation

Alshwawra, A 2023, 'Development of advanced cylinder liner conformation concepts of internal combustion engines with numerical simulation methods', Doktor der Ingenieurwissenschaften, Gottfried Wilhelm Leibniz Universität Hannover, Hannover. https://doi.org/10.15488/14439
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title = "Development of advanced cylinder liner conformation concepts of internal combustion engines with numerical simulation methods",
abstract = "Internal combustion engine (ICE) represents the main pillar of the powertrain in the majority of road, marine freight, and transportation worldwide. With the absence of a real alternative that can replace ICE over its full range of applications, enhancing the efficiency of ICE is of great interest to save energy and reduce greenhouse gas emissions. A great improvement potential is seen in the piston ring – cylinder liner (PRCL) coupling which is responsible to maintain the combustion pressure in the cylinder while preventing lubricant oil leak to it. Large frictional losses are associated with this sealing function. In order to improve the PRCL conformability with less friction, a rounder liner cross section is targeted in the hot operational state. The rounder the liner is, the better conformability exists. To achieve that, the engine must be started with a non-circular liner that deforms in a controlled manner under engine thermal and mechanical loads to form a circular liner bore during the fire operation. Further tribological improvement can be achieved by targeting a non-prismatic circular bore shape in the hot operational state. This cumulative thesis presents numerical investigations to this reverse engineering approach with the aim to reach a specific liner shape in the fire operation state from non-cylindrically produced liners in the cold state. It follows the relevant research hypothesis and provides quantitative analysis to show the advantages and limitations of such an approach. The presented numerical work is based on advanced simulation techniques established on the basis of finite element methods. Two physical models were considered; one for a series gasoline engine, and the second for a single cylinder diesel engine test rig. The models were validated using experimental data, then the local deformations of the liners were simulated. Harmonic analysis was used to investigate the orders of deformations and their trends over a set of operational points. Then different forms of non-circular liners were designed based on the reverse engineering concept. Geometrical performance indicators were developed and used in the comparative analysis. The results show a significant improvement in the geometrical performance when using non-circular liners. Special freeform liner can improve the bore roundness by 95% and the straightness by 75%. The concept of dominant deformation order can simplify the design significantly. For example, the elliptical conus liner is a good yet simpler alternative with 85% improvement in roundness and 65% in the straightness of the liner during fire operation. The freeform liner is susceptible to the engine load. However, some deformation orders are independent of operational points and can be considered in the liner design. The results presented here show a great potential of tribological improvement. A parallel experimental work shows a significant reduction of frictional losses by using one of the liners that was designed in this thesis.",
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doi = "10.15488/14439",
language = "English",
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Download

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T1 - Development of advanced cylinder liner conformation concepts of internal combustion engines with numerical simulation methods

AU - Alshwawra, Ahmad

PY - 2023

Y1 - 2023

N2 - Internal combustion engine (ICE) represents the main pillar of the powertrain in the majority of road, marine freight, and transportation worldwide. With the absence of a real alternative that can replace ICE over its full range of applications, enhancing the efficiency of ICE is of great interest to save energy and reduce greenhouse gas emissions. A great improvement potential is seen in the piston ring – cylinder liner (PRCL) coupling which is responsible to maintain the combustion pressure in the cylinder while preventing lubricant oil leak to it. Large frictional losses are associated with this sealing function. In order to improve the PRCL conformability with less friction, a rounder liner cross section is targeted in the hot operational state. The rounder the liner is, the better conformability exists. To achieve that, the engine must be started with a non-circular liner that deforms in a controlled manner under engine thermal and mechanical loads to form a circular liner bore during the fire operation. Further tribological improvement can be achieved by targeting a non-prismatic circular bore shape in the hot operational state. This cumulative thesis presents numerical investigations to this reverse engineering approach with the aim to reach a specific liner shape in the fire operation state from non-cylindrically produced liners in the cold state. It follows the relevant research hypothesis and provides quantitative analysis to show the advantages and limitations of such an approach. The presented numerical work is based on advanced simulation techniques established on the basis of finite element methods. Two physical models were considered; one for a series gasoline engine, and the second for a single cylinder diesel engine test rig. The models were validated using experimental data, then the local deformations of the liners were simulated. Harmonic analysis was used to investigate the orders of deformations and their trends over a set of operational points. Then different forms of non-circular liners were designed based on the reverse engineering concept. Geometrical performance indicators were developed and used in the comparative analysis. The results show a significant improvement in the geometrical performance when using non-circular liners. Special freeform liner can improve the bore roundness by 95% and the straightness by 75%. The concept of dominant deformation order can simplify the design significantly. For example, the elliptical conus liner is a good yet simpler alternative with 85% improvement in roundness and 65% in the straightness of the liner during fire operation. The freeform liner is susceptible to the engine load. However, some deformation orders are independent of operational points and can be considered in the liner design. The results presented here show a great potential of tribological improvement. A parallel experimental work shows a significant reduction of frictional losses by using one of the liners that was designed in this thesis.

AB - Internal combustion engine (ICE) represents the main pillar of the powertrain in the majority of road, marine freight, and transportation worldwide. With the absence of a real alternative that can replace ICE over its full range of applications, enhancing the efficiency of ICE is of great interest to save energy and reduce greenhouse gas emissions. A great improvement potential is seen in the piston ring – cylinder liner (PRCL) coupling which is responsible to maintain the combustion pressure in the cylinder while preventing lubricant oil leak to it. Large frictional losses are associated with this sealing function. In order to improve the PRCL conformability with less friction, a rounder liner cross section is targeted in the hot operational state. The rounder the liner is, the better conformability exists. To achieve that, the engine must be started with a non-circular liner that deforms in a controlled manner under engine thermal and mechanical loads to form a circular liner bore during the fire operation. Further tribological improvement can be achieved by targeting a non-prismatic circular bore shape in the hot operational state. This cumulative thesis presents numerical investigations to this reverse engineering approach with the aim to reach a specific liner shape in the fire operation state from non-cylindrically produced liners in the cold state. It follows the relevant research hypothesis and provides quantitative analysis to show the advantages and limitations of such an approach. The presented numerical work is based on advanced simulation techniques established on the basis of finite element methods. Two physical models were considered; one for a series gasoline engine, and the second for a single cylinder diesel engine test rig. The models were validated using experimental data, then the local deformations of the liners were simulated. Harmonic analysis was used to investigate the orders of deformations and their trends over a set of operational points. Then different forms of non-circular liners were designed based on the reverse engineering concept. Geometrical performance indicators were developed and used in the comparative analysis. The results show a significant improvement in the geometrical performance when using non-circular liners. Special freeform liner can improve the bore roundness by 95% and the straightness by 75%. The concept of dominant deformation order can simplify the design significantly. For example, the elliptical conus liner is a good yet simpler alternative with 85% improvement in roundness and 65% in the straightness of the liner during fire operation. The freeform liner is susceptible to the engine load. However, some deformation orders are independent of operational points and can be considered in the liner design. The results presented here show a great potential of tribological improvement. A parallel experimental work shows a significant reduction of frictional losses by using one of the liners that was designed in this thesis.

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