S. Kavinprasad, S. Shankar and M. Karthic
The purpose of this paper is to test mechanical face seals made of carbon/SS316 with different coolants for evaluating its tribological performance. The reliability of a…
Abstract
Purpose
The purpose of this paper is to test mechanical face seals made of carbon/SS316 with different coolants for evaluating its tribological performance. The reliability of a mechanical seal mainly depends on the seal materials and the type of coolant used for the lubrication.
Design/methodology/approach
Compressed air, vacuum and nitrogen are the main coolants utilized for the experimental work, and the obtained results are compared with the dry running case for a specified period. The experimental results are also validated with the computational fluid dynamics (CFD) simulation results.
Findings
The results shows that the sealing pressure, sliding speed and materials used would be the predominant factors for the seal design. Over compressed air, vacuum and nitrogen cooling techniques were found to be more efficient.
Originality/value
The experimental results are also validated with the CFD simulation results. This paper also emphasizes the usage of vacuum as a cooling medium in industries, which will enhance the seal life at an economical cost over nitrogen.
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S. Shankar and P. Krishnakumar
The purpose of this study was to investigate the frictional characteristics of the mechanical seals by using an efficient pairing by providing a suitable lubricant. Among all…
Abstract
Purpose
The purpose of this study was to investigate the frictional characteristics of the mechanical seals by using an efficient pairing by providing a suitable lubricant. Among all techniques and lubrication, deposition of solid lubricants on the sliding surface of the mechanical seal was found to be the most effective method to reduce frictional coefficient, frictional force and seal face temperature, thereby increasing the life time of mechanical seal.
Design/methodology/approach
In this study, two coatings, diamond-like carbon (DLC) and tungsten carbide/carbon (WC/C), was deposited over the stationary high-carbon high-chromium steel ring paired with resin-impregnated carbon. Their frictional characteristics were studied under various classes of liquid lubricants such as organic liquids, synthetic oil, mineral oil and vegetable oils using an experimental approach. Further, among all classes of liquid lubricants, the one which showed better frictional characteristics was mixed with 0.5, 1 and 2 wt% of potential environmental friendly solid lubricant – boric acid powder.
Findings
The high hardness and low surface roughness of DLC- and WC/C-coated seal with the lubricant of palm olein oil containing 1 wt% of boric acid powder contributed a hybrid tribofilm and resulted in low and stable friction coefficient in the range of 0.04-0.05 without any measurable wear.
Originality/value
A pair involving stationary DLC- and WC/C-coated seal ring and resin-impregnated carbon seal rotating ring for the application of mechanical seal was suggested and its frictional characteristics were studied under various classes of lubricants.
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Penggao Zhang, Boqin Gu, Jianfeng Zhou and Long Wei
The purpose of this study is to investigate the hydrodynamic lubrication characteristics of ferrofluid film for spiral groove mechanical seal in external electromagnetic field and…
Abstract
Purpose
The purpose of this study is to investigate the hydrodynamic lubrication characteristics of ferrofluid film for spiral groove mechanical seal in external electromagnetic field and to analyze the effects of the volume fraction of ferrofluid, parameters of the electromagnetic field, operating parameters and geometrical parameters of mechanical seal on the characteristics of ferrofluid film.
Design/methodology/approach
The relationship between the ferrofluid viscosity and the intensity of external electromagnetic field was established. Based on the Muijderman narrow groove theory, the pressure distribution was calculated with the trial method by trapezoid formula.
Findings
It was found that pressure, average viscosity, average density and opening force of ferrofluid between end faces increase with the increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential and spiral angle; decrease with the increase in temperature; and increase at first and then decrease with the increase in the ratio of groove width to weir and the groove length. All of them reach the maximum value when the ratio of width of groove to weir is 0.7 and the ratio of groove length is 0.6. Leakage of ferrofluid increases with an increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential, spiral angle and ratio of groove length; decreases with an increase in temperature; and increases at first and then decreases with the increase in the ratio of groove width to weir. The tendencies of characteristics of silicone oil are consistent with those of ferrofluid, and the characteristics of silicone oil are smaller than those of ferrofluid under the same condition.
Originality/value
The volume fraction of ferrofluid, rotating speed, spiral angle, ratio of groove width to weir, groove length and temperature have a significant influence on the characteristics of ferrofluid film; however, intensity of current and the pressure differential have slight influence on the characteristics of ferrofluid film. An analytical method for analyzing hydrodynamic lubrication characteristics of ferrofluid film in a spiral groove mechanical seal was proposed based on the Muijderman narrow groove theory.
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Cheng Zhang, Jianfeng Zhou and Xiannian Meng
In the magnetorheological fluid (MRF) sealing, a large amount of friction heat is generated in the fluid film with micron thickness due to the viscosity dissipation, which leads…
Abstract
Purpose
In the magnetorheological fluid (MRF) sealing, a large amount of friction heat is generated in the fluid film with micron thickness due to the viscosity dissipation, which leads to seal failure and MRF deterioration. The purpose of this study is to investigate the mechanism of temperature rise of MRF film under the action of the three-field coupling of the flow field, temperature field and magnetic field.
Design/methodology/approach
The fluid film was simplified as a Couette flow in this work to simulate the temperature change in the sealing fluid film under different working conditions. The corresponding experiment for test the temperature rise was also carried out, and the temperature of the characteristic point of the stationary ring was measured to validate the model.
Findings
The results show that the temperature rise is mainly affected by the rotational speed, magnetic field strength and fluid film thickness. The magnetic field enhances the convective heat transfer in the MRF film. The thinner the fluid film, the more frictional heat generated. The MRF film reaches its maximum temperature at the contact with the end face of rotating ring due to frictional heat.
Originality/value
A method for temperature rise analysis of MRF fluid sealing films based on Couette flow is established. It is helpful for the study of liquid film frictional heat in MRF seals.