Effects of Nanoparticle Enhanced Lubricant Films in Thermal Design of Plain Journal Bearings at High Reynolds Numbers

Abstract

Performance investigation of oil journal bearings is of particular importance given the growing use of them as a support for rotary components in a wide range of industrial machines. Frictional forces and shear stresses, which are proportionate to the velocity of lubricating layers at different points in the bearing space, provide the basis for changing temperature conditions. Various factors such as rotational velocity increase, slip width reduction, and small heat transfer coefficient of lubricant cause intensification of lubricant temperature changes. In the present study, with using computational fluid dynamic (CFD) thermohydrodynamic (THD) numerical simulations, the effect of nanoparticles on the performance features of plain journal bearings is evaluated. Particularly, 3D simulation of a journal bearing is implemented using CFD which considerably improves the accuracy of results, coupled with conjugate heat transfer model for metal parts of bearings. Reynolds equation model is used to calculate the oil-film pressure developed in hydrodynamic journal bearings by applying the nano-based lubricants. The configuration of thrust bearing consists of six pads in this study. In order to reduce the modeling complexity and computational cost and because of the symmetrical geometry of the pads, simulation of a single pad is considered instead of the entire domain. In this study, TiO2 nanoparticle with different volume fraction percentages are used. The parameters that are changed to evaluate the performance of the bearing include volume fraction percentage of the nanoparticle, type of lubricant, and rotational speed. Based on the results, for all different lubricant types, the dissipation power, average shear stress, and temperature rise are increased with augmenting the rotational speed. By increasing the rotational speed from 500 to 1500 rpm, the average shear stress increases by more than 100%, 120%, and 130% for DTE 26, DTE 25, and DTE 24 lubricant types, respectively. Moreover, by increasing the rotational speed from 500 to 1500 rpm, the dissipation power, and temperature rise are increased around 600% and 800%, respectively. Furthermore, increasing nanoparticles volume fraction from 0% to 10%, increases all parameters by approximately 10% for all lubricant types and in all rotational speeds.

Analysis of melting of phase change material inserted a block via impinging turbulent slot jet

“…Their results showed that the thermal conductivity of Ag-multi-walled carbon nanotube/water HNFs is higher than that of multi-walled carbon nanotube nanofluids. Jamalabadi et al (2019) performed the impact of nanoparticles on the performance of plain journal bearings using computational fluid dynamics (CFD)-based thermohydrodynamic (THD) numerical simulations. The simulations are conducted in 3 D, incorporating a conjugate HT model for accurate results.…”

Entropy generation and MHD analysis of a nanofluid with peristaltic three dimensional cylindrical enclosures

“…They proposed that fluid containing hybrid nanoparticles prominently interrelate with tumors and accurately delivers drugs to a particular portion of the diseased organ. More suitable studies on the peristaltic flow of nanofluids can be cited in Khan et al (2019), Elelamy et al (2020), Ellahi et al (2019), Moravej et al (2020) and Abdollahzadeh Jamalabadi et al(2019).…”

A Review of the Methods of Modeling Multi-Phase Flows within Different Microchannels Shapes and Their Applications

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