Laser-induced fluorescence measurements in a single-ring test rig: Evidence of cavitation and the effect of different operating conditions and lubricants in cavitation patterns and initiation

Dellis, Polychronis

doi:10.1177/1468087418819254

Cited by 13 publications

(48 citation statements)

References 32 publications

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“…They also showed that the oil film thickness, obtained from capacitance probe, increases with speed while it decreases with load; the results were confirmed by other researchers. Most recently, [16] reported the measurement of the oil film thickness for different lubricant using LIF and showed that the formulation and chemistry of the lubricant play a major role in the oil film thickness curves and that the cavitation structure is affected by speed and load. Another useful technique to visualise and measure cavitation bubble formation and its thickness is the digital holography method, which was described by [17] and used for the first time in an optical sliding bearing system.…”

Section: Introductionmentioning

confidence: 99%

Effect of Viscosity and Speed on Oil Cavitation Development in a Single Piston-Ring Lubricant Assembly

et al. 2019

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A high-speed camera has been used to produce unique time-resolved images of high quality to describe the dynamics of the lubricant flow and cavitation characteristics in a sliding optical liner over a fixed single piston-ring lubricant assembly for three lubricants with different viscosities to establish their impact on cavitation formation and development. The images were obtained at two cranking speeds (or liner sliding velocity) of 300 rpm (0–0.36 m/s) and 600 rpm (0–0.72 m/s), at a lubricant temperature of 70 °C and a supply lubricant rate of 0.05 L/min. A special MATLAB programme has been developed to analyse the cavitation characteristics quantitatively. The dynamic process of cavities initiation was demonstrated by time-resolved images from fern cavity formation to fissure cavities and then their development to the sheet and strings cavities at a liner sliding velocity of around 0.17 m/s. The results for both up- and down-stroke motions showed that the cavities reach their fully developed state downstream of the contact point when the liner velocity reaches its highest velocity and that they start to collapse around TDC and BDC when the liner comes to rest. Within the measured range, viscosity had a great influence on length of cavities so that a decrease in viscosity (from Lubricant A to C) caused a reduction in length of cavities of up to 35% for Lubricant C. On the other hand, an increase in speed, from 300 rpm to 600 rpm, have increased the number of string cavities and also increased the length of cavities due to thicker oil film thickness with the higher speed. Overall, the agreement between the processed data by MATLAB and visualisation measurements were good, but further thresholds refinement is required to improve the accuracy.

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Section: Introductionmentioning

confidence: 99%

Effect of Viscosity and Speed on Oil Cavitation Development in a Single Piston-Ring Lubricant Assembly

et al. 2019

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“…As velocity lowers the regime from hydrodynamic turns to mixed and further on, the surfaces cannot separate and the lubrication returns to mixed lubrication. At this point the developed forms of cavities diminish into bubbles and the effect of the squeeze film takes place at the other end of the stroke [1,8,9,12].…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Engine oil formulation should be specifically blended to provide optimum all-around performance according to the engineering specifications [1]. These include the enhancement of load carrying capacity, where the appearance of different forms of cavitation has the opposite effect [1,2,3].…”

Section: Introductionmentioning

confidence: 99%

“…According to Rastogi and Gupta [4] the primary purpose of the additives is to reduce the dependence of lubricant viscosity on temperature. Polymer addition enhances viscoelastic properties and the oil properties turn to slightly shear-thinning [1,4]. It was speculated that shear-thinning results in a larger cavitation zone.…”

Section: Introductionmentioning

confidence: 99%

“…It was speculated that shear-thinning results in a larger cavitation zone. Lubricant viscosity is subject to shear stress apart from the apparent temperature effect [1]. The addition of viscoelastic additives raises the load carrying capacity and reduces any wear that might occur [5].…”

Section: Introductionmentioning

confidence: 99%

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Temperature Effect in Minimum Oil Film Thickness Measurements in a Simplified Single-Ring Test Rig Used to Simulate the Piston-Cylinder Assembly

Dellis¹

2019

PES

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As part of the study of the complex lubrication phenomena between the piston-ring and the cylinder liner, it is important to characterize the oil film thickness in view of new designs that can be implemented for the piston-ring assembly. In previous studies parametric results of different lubricants, speed, load, temperature and piston-ring surface were presented to complement on the cavitation rheological phenomena (initiation and development) and to interpret the effect of physical-chemical properties of the lubricants in oil film thickness, friction and oil film pressure. Measurements were conducted in a simplified single-ring test rig, where a steady piston-ring section of overall width 5 mm is placed under a flat surface used as a reciprocating liner, taking advantage of significantly less uncertainties when compared to engine experiments. The advantage of this layout is that it can provide abundance of results that in turn, are being simultaneously interpreted in an easier and safer way prior to engine implementation and testing. In this manner, the effect of different operating conditions is assessed to achieve solid experimental results, useful in engine tribological applications in the piston-cylinder assembly, that comply with the emission regulations of today and the near future. This presentation is focused on the effect of temperature in minimum oil film thickness measurements (MOFT) for different lubricants. An electrical method is used in this set of experiments to measure the oil film thickness (capacitance). The testing is applied for different speeds and loads so that a complete picture of the lubricants behavior can be taken and, in parallel, friction measurements are presented to assess the MOFT results for specific parts of the stroke. The results show the effect of different lubricant properties in MOFT and give an insight of the conditions of cavitation occurrence at the early parts of the stroke as temperature rises. Further processing of these results provides very useful conclusions and the combination of the lubricants behavior under cavitating conditions, can lead to innovative additives design-formulation and new lubricant properties.

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An in-situ measurement approach for the oil film characteristics of the spherical valve plate pair in axial piston pumps

Ma,

Liu,

et al. 2024

Measurement

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Laser-induced fluorescence measurements in a single-ring test rig: Evidence of cavitation and the effect of different operating conditions and lubricants in cavitation patterns and initiation

Cited by 13 publications

References 32 publications

Effect of Viscosity and Speed on Oil Cavitation Development in a Single Piston-Ring Lubricant Assembly

Effect of Viscosity and Speed on Oil Cavitation Development in a Single Piston-Ring Lubricant Assembly

Temperature Effect in Minimum Oil Film Thickness Measurements in a Simplified Single-Ring Test Rig Used to Simulate the Piston-Cylinder Assembly

An in-situ measurement approach for the oil film characteristics of the spherical valve plate pair in axial piston pumps

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