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Hydrogen has been identified as a promising decarbonization fuel in internal combustion engine (ICE) applications in many areas including heavy-duty on- and off-road, power-generation, marine, etc. Hydrogen ICEs can achieve high power density and very low tailpipe emissions. However, there are challenges; designing systems for a gaseous fuel with its own specific mixing, burn rate and combustion control needs, which can differ from legacy products. The primary pollutant of concern for Hydrogen ICEs is NOx which can be addressed by running the engine at very lean equivalence ratios and the use of Exhaust Gas Recirculation (EGR). Computation Fluid Dynamics (CFD) is a valuable tool to model the combustion characteristics under different conditions, as presented in SAE-2023-01-0197 [1], which can also be used to predict thermal loading.

The authors have published SAE paper 2008-01-0088 on the analytical comparison between 4 and 8 counterweight crankshafts for an I4 gasoline engine. This paper showed that for a particular design of a 4 counterweight crankshaft, the differences in bearing force and oil film thickness were very small and the only major difference in terms of bearing shaft tilt angle occurred at mains 2 and 4 (increase of ∼20% compared with 8 counterweight version). The 4 counterweight crankshaft has a significant mass advantage as it was 1.42kg lighter than the 8 counterweight crankshaft. This new paper addresses the testing performed to validate the analysis results in bearing durability by subjecting the engine to a mixture of high speed and general durability cycles. A comparison was made on the bearing conditions after running a total of 100 hours through prescribed durability cycles on a gasoline engine with both 4 and 8 counterweight crankshafts.

This paper presents results of an analytical comparison between two alternative versions of a crankshaft for a 2.2L gasoline engine. The first version had 8 counterweights and a bay balance factor of 80.3%. The second had 4 (larger) counterweights giving a bay balance factor of 56.6% and a crankshaft mass reduction of 1.42 kg. The results presented in this paper relate to the main bearings in terms of specific loads, oil film thickness and shaft tilt angle under full load and no load conditions across the speed range. Torsional vibration analysis and crankshaft stress analysis were also performed but the results are not presented here. The differences in bearing force and oil film thickness were very small and the only major difference in terms of shaft tilt angle occurred at Mains 2 and 4 (increase of ∼ 20% compared with 8 counterweight version).

A numerical study of the interactions between hydrodynamic lubrication, oil transport and radial dynamics of a piston ring using a Navier-Stokes equation solution including surface tension effect is presented. The scheme, which is outlined in this investigation, facilitates the calculation of the distribution of oil accumulating at the leading and trailing areas surrounding the piston ring as it scrapes against the liner and explains the experimentally observed lubricating oil free surface profiles. The calculation of this oil distribution is important in the estimation of lubricating oil consumption in engines. The numerical procedure employed in this study is capable of depicting the transition between the various modes of piston ring lubrication (hydrodynamic, mixed and boundary) over an engine cycle, including the detachment of oil film from the ring and its subsequent re-attachment.

This paper describes the design and analysis of a lightweight crankshaft for a high speed racing motorcycle engine. It covers the evolution of the crankshaft from the baseline, with rated speed of 14000 rpm, to the final design with rated speed of 16000 rpm. The lightweight crankshaft is compared with the baseline design in terms of the following criteria. Balance Mass and rotating inertia Main bearing loads and oil film thickness Torsional vibration Stress and fatigue safety factor

The main objective of this research was to validate the friction prediction capability of Ricardo Software products PISDYN and RINGPAK by comparing predictions with measured piston assembly friction force. The measurements were made by the University of Leeds on a single cylinder Ricardo Hydra gasoline engine using an IMEP method developed by the University. This technique involves the use of advanced instrumentation to make accurate measurements of cylinder pressure, crankshaft angular velocity and connecting rod strain. These measured values are used to calculate the forces acting on the piston assembly including the friction force. PISDYN was used by Ricardo to calculate friction force at the interface between the piston skirt and cylinder liner. The model used includes the effects of secondary dynamics, partial lubrication and piston skirt profile. RINGPAK was used by Ricardo to calculate the friction force at each piston ring.

Elasto-Hydrodynamic Lubrication (EHL) analysis of a fully flooded piston skirt-liner conjunction is a useful methodology for design analysis of pistons. However, under typical engine operating conditions, oil present in the clearance region between the skirt and liner is sufficient to wet only a portion of the piston skirt (partial skirt lubrication). The reduction in damping due to partial skirt lubrication is an important consideration to address issues related to piston slap noise, liner cavitation and other noise and vibration aspects. The existing simulation methodology for EHL analysis of a fully flooded piston skirt uses a finite-difference scheme to solve the coupled Reynolds, Greenwood-Tripp and elasticity equations in order to calculate the nodal oil film pressures, contact pressures and elastic deformations respectively. Detection of cavitation zones within the oil film done via implementation of the Half-Sommerfeld boundary condition.