The effect of diesel knock on a turbocharged diesel engine emissions and top compression ring friction

Anastasios Zavos,Alasdair Cairns,Apostolos Pesyridis,Pantelis G Nikolakopoulos

doi:10.1051/matecconf/202134904006

Anastasios Zavos, Alasdair Cairns + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/202134904006

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Abstract

Turbocharged engines with direct injection offer a significant contribution to engine downsizing technology. However, there remain many unsolved and ambitious issues concerning knocking and pre-ignition. Therefore, detailed understanding of the top compression ring lubrication and fuel economy is critical. This paper focuses on the tribological performance of the top compression ring under partially lubricated conditions caused by diesel knock in a turbocharged diesel engine. A mixed-hydrodynamics model was built including multi-phase flow and asperity interactions with realistic boundary conditions. The study shows that frictional power losses in the compression ring-liner contact increased owing to diesel knock and starved conditions in a turbocharged gasoline engine. This finding indicates that the control of knocking combined with the inlet flow conditions can help to mitigate fuel economy and emissions in ring-liner conjunction.

Highlights

One opportunity to reduce fuel consumption and to increase engine peak power of SI engines is downsizing
According to Richardson [4], the top compression ring friction is considered to be between 13% and 40% of all the parasitic losses depending on the engine and the running conditions
The studied compression ring was from a four-stroke turbocharged diesel engine

Summary

Introduction

One opportunity to reduce fuel consumption and to increase engine peak power of SI engines is downsizing. As the piston reciprocates along the cylinder bore, the top compression ring is pushed radially against the cylinder liner with variable forces including the pretension force and the gas force generated from the in-cylinder pressure. For this reason, the friction losses increased while the surfaceto-surface contact occurs. The suitable inlet condition is essential for realistic prediction of starvation For this reason, much attention has been devoted to the investigation of this phenomenon including power loss and lubricant availability [8,9,10]. The effect of ‘’coating-lubricant’’ subsystem on boundary friction was investigated

ANALYSIS OF PISTON RING-LINER CONTACT

Mixed lubrication

Lubricant viscosity

CFD model

Results and Discussion

Conclusions