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Modelling and evaluating piston slap-induced cavitation of cylinder liners in heavy-duty diesel engines

Liu Dong, Sun Nannan, Zhu Guixiang, Cao Hengchao, Wang Tie, Li Guoxing, Gu Fengshou

Eksploatacja i Niezawodność

2023

Vol. 25, no. 3

art. no. 169644

Cavitation erosion of cylinder liner seriously affects the operational reliability and service life of heavy-duty diesel engines. The accuracy of the modeling-based cavitation risk evaluation is limited by the unclear correspondence between cylinder liner vibration and coolant cavitation. This report is intended to investigate the correspondence between cylinder liner vibration and coolant pressure by combining vibration cavitation test, pressure gradient calculation, and visualization observation. The cavitation risk of the cylinder liner under the piston slap is quantitatively analyzed based on a nonlinear structural dynamics model that incorporates the piston-cylinder liner nonlinear collision, piston thermal deformation, and preload of cylinder head. The results show that the occurrence of cavitation will cause a nonlinear relationship between the cylinder liner acceleration and the coolant pressure. The engine under study has a high risk of cavitation when the cylinder liner acceleration exceeds 1189 m/s2. The difference in cavitation risk for each cylinder is related to the structural modal characteristics of the crankcase. In addition, the effect of piston-liner clearance and piston pin offset on the cavitation risk is investigated based on the dynamics model.

Air Pollution Reduction and Environment Protection Using Methane Fuel for Turbocharged CI Engines

Ghazal O. H.

Journal of Ecological Engineering

2018

Vol. 19, nr 5

52--58

The internal combustion engine is considered as one of the main sources for air pollution due to hydrocarbon fuel combustion. The increased land transport usage requires improvement of the engine efficiency and combustion process technology to reduce the engine emissions. A turbocharged engine and the gaseous fuel replacement are the green tools proposed by researchers to enhance fuel saving and emissions reduction. In this paper, both methods were investigated. The methane is a preferred gaseous fuel due to its lower carbon to hydrogen ratio, resulting in lesser HC and CO emissions. In this paper, a turbocharged compression ignition engine with methane/diesel dual fuel is simulated using professional GT-power code to investigate the effect of methane percentage in mixture on the engine performance and emissions. A turbocharged 6 cylinders compression ignition engine has been built and investigated. During the simulation, the methane/diesel ratios were varied from pure diesel with zero percent methane to 90% methane concentration by mass with 10% increment every run. The results show that the engine brake power and specific fuel consumption increased while the thermal efficiency decreased for lower CH4 concentration. For higher CH4 percentage, the brake power and thermal efficiency increased while specific fuel consumption decreased. Moreover, NO emission has 35% reduction compared to neat diesel fuel when 50% of methane was added to the mixture. Conversely, the CO and HC concentration increased when the methane ratio is less than 50% compared to neat diesel combustion. In general, the engine efficiency improved when methane was added to diesel fuel in compression ignition engine with turbocharger boost, resulting in lesser emissions and cleaner environment.