On elastic deformation, inter-asperity cavitation and lubricant thermal effects on flow factors

Meng, Fanzhi; Cen, Shao Qi; Hu, Yanqiang; Wang, H.

doi:10.1016/j.triboint.2008.06.009

Cited by 22 publications

(12 citation statements)

References 18 publications

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“…In addition, a simple method for calculating the contact factor for non-Gaussian surfaces is also presented. Interested readers can refer to the relevant studies [45][46][47][48].…”

Section: Mixed Lubrication Model Of Crosshead Slipperguide Friction Pairmentioning

confidence: 99%

Transient tribo-dynamic analysis of crosshead slipper in low-speed marine diesel engines during engine startup

Meng

Dong

et al. 2020

Friction

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A crosshead slipper-guide system, which bears a significant thrust force, is an essential friction pair in low-speed marine diesel engines. Owing to the low moving speed of the crosshead slipper during engine startup, it is difficult to form good hydrodynamic lubrication between the crosshead slipper and guide. Therefore, a detailed analysis of the crosshead slipper during engine startup is needed. In this study, a new transient tribo-dynamic model for a crosshead slipper during the engine startup process is presented. The model consists of a mixed lubrication model of the crosshead slipper-guide and dynamic models of the piston assembly, crosshead assembly, connecting rod, and crankshaft. The tribo-dynamic performances of the crosshead slipper during startup and under the rated conditions were simulated and compared. The results show that the tribo-dynamics of the crosshead slipper during the startup process are significantly different from those under the rated conditions. Some measures beneficial for the low friction of a crosshead slipper-guide under the rated conditions may significantly increase the friction loss of the crosshead slipper-guide system during the startup process.

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“…In addition, a simple method for calculating the contact factor for non-Gaussian surfaces is also presented. Interested readers can refer to the relevant studies [45][46][47][48].…”

Section: Mixed Lubrication Model Of Crosshead Slipperguide Friction Pairmentioning

confidence: 99%

Transient tribo-dynamic analysis of crosshead slipper in low-speed marine diesel engines during engine startup

Meng

Dong

et al. 2020

Friction

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“…Exactly this relation between the flow of rough and ideal smooth lubricating gaps is known as the flow factor and can be implemented into the macroscopic Reynolds equation. Improvements to the original method of Patir & Cheng were made, for example, by the implementation of real surface topographies, and no virtual generated ones, and the consideration of cavitation effects [19,20]. Using the Reynolds equation is recommended as long as the errors due to the derivation from the Navier-Stokes equations are small.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

et al. 2020

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Optimizing the surface topography of cast iron crankshafts offers the opportunity to use this material as an alternative to steel in high-performance combustion engines. In the past, this was not possible due to the higher wear on bearing shells and the higher friction losses in relation to forged steel shafts. In order to find an optimized shaft micro topography, the friction and wear behavior of steel and cast iron shafts with different surface treatments were compared to each other, using a combined physical (experimental) and a virtual (computational) simulation approach. The experiments were carried out with a rotary tribometer using a journal bearing test configuration with the possibility to test real-life bearing shells and shaft specimens, manufactured from real-life crankshafts. In the experiments, a polished steel shaft with low bearing wear was effective. The optimization of cast iron crankshafts by a novel surface treatment showed a significant reduction of bearing wear in relation to the classical surface finishing procedures of cast iron shafts. A computational simulation approach, considering the real-life micro topography by using the Navier–Stokes equations for the calculation of micro hydrodynamics, supports the assessment of fluid friction. The virtual simulation shows, in accordance to the experimental results, only a minor influence of the investigated shaft topographies on the fluid friction. Further optimization of shaft surfaces for journal bearing systems seems possible only by the usage of patterned micro topographies.

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“…With advancing technology regarding the 3D acquisition of surfaces, the application of Patir and Cheng's method became practicable for real surfaces [19][20][21]. In recent years, the method by Patir and Cheng has been adopted and expanded to be able to take effects like micro cavitation, elastic deformation, thermal effects and also solid contacts into account [22,23]. Lunde and Tonder [24] discuss the validity of the boundary conditions chosen by Patir and Cheng.…”

Section: Introductionmentioning

confidence: 99%

A Novel Approach for Modeling Surface Effects in Hydrodynamic Lubrication

et al. 2018

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Abstract:The common approach for the flow factor calculation is based on using the Reynolds equation to simulate the micro-level flow. However, for structured surfaces the fluid flow cannot be represented correctly, due to the assumptions made when deriving the Reynolds equation. In this work, a novel method using the Navier-Stokes equations for the calculation of the micro-level flow is presented and validated against results from Patir and Cheng. The three-dimensional lubrication gap was generated by a rough Gaussian random surface and a perfectly smooth moving counter surface, in order to be available for different numerical methods. The presented results illustrate similar trends for both the approaches. Additionally, the use of the Navier-Stokes equations allows for the observance of surface induced effects which cannot be resolved by the approach of Patir and Cheng. Furthermore, a numerical approach for a shear flow factor calculation with a rough moving surface is presented and validated against other simulation methods. While the validation is maintained with pressure-and temperature-independent density and viscosity, these effects will be taken into account for later research activities of textured surfaces.

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On elastic deformation, inter-asperity cavitation and lubricant thermal effects on flow factors

Cited by 22 publications

References 18 publications

Transient tribo-dynamic analysis of crosshead slipper in low-speed marine diesel engines during engine startup

Transient tribo-dynamic analysis of crosshead slipper in low-speed marine diesel engines during engine startup

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

A Novel Approach for Modeling Surface Effects in Hydrodynamic Lubrication

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