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Abstract The ASTM D130 was first issued in 1922 as a tentative standard for the detection of corrosive sulfur in gasoline. A clean copper strip was immersed in a sample of gasoline for three hours at 50°C with any corrosion or discoloration taken to indicate the presence of corrosive sulfur. Since that time, the method has undergone many revisions and has been applied to many petroleum products. Today, the ASTM D130 standard is the leading method used to determine the corrosiveness of various fuels, lubricants, and other hydrocarbon-based solutions to copper. The end-of-test strips are ranked using the ASTM Copper Strip Corrosion Standard Adjunct, a colored reproduction of copper strips characteristic of various degrees of sulfur-induced tarnish and corrosion, first introduced in 1954. This pragmatic approach to assessing potential corrosion concerns with copper hardware has served various industries well for a century.

Abstract Three-dimensional patterns representing crosshatched plateau-honed cylinder bores based on two-dimensional Fast Fourier Transform (FFT) of measured surfaces were generated and used to calculate pressure flow, shear-driven flow, and shear stress factors. Later, the flow and shear stress factors obtained by numerical simulations for various surface patterns were used to calculate lubricant film thickness and friction force between piston ring and cylinder bore contact in typical diesel engine conditions using a mixed lubrication model. The effects of various crosshatch honing angles, such as 30°, 45°, and 60°, and texture heights on engine friction losses, wear, and oil consumption were discussed in detail. It is observed from numerical results that lower lubricant film thickness values are generated with higher honing angles, particularly in mixed lubrication regime where lubricant film thickness is close to the roughness level, mainly due to lower resistance to pressure flow.

Abstract Due to the incoming phase out of fossil fuels from the market in order to reduce the carbon footprint of the automotive sector, hydrogen-fueled engines are candidate mid-term solution. Thanks to its properties, hydrogen promotes flames that poorly suffer from the quenching effects toward the engine walls. Thus, emphasis must be posed on the heat-up of the oil layer that wets the cylinder liner in hydrogen-fueled engines. It is known that motor oils are complex mixtures of a number of mainly heavy hydrocarbons (HCs); however, their composition is not known a priori. Simulation tools that can support the early development steps of those engines must be provided with oil composition and properties at operation-like conditions. The authors propose a statistical inference-based optimization approach for identifying oil surrogate multicomponent mixtures. The algorithm is implemented in Python and relies on the Bayesian optimization technique.

Abstract To reduce particulate emissions, the use of particulate filters in diesel engines is meanwhile state of the art, while the integration of such systems in gasoline engines is now also necessary in order to comply with today’s regulations. Over its lifetime, a gasoline particulate filter (GPF) collects ash components of fuel, lubrication oil, and materials originating from the catalytic coating and from engine abrasion. In the development and application process, synthetic ashing from GPFs is challenging. The ash of the lubrication oil can be increased in various ways, like oil-doped fuel, a separate oil burner, or changes in the piston-cylinder system of the engine. However, these methods show major disadvantages.

Abstract The acidification of lubricating oils during engine operation, and the subsequent additive neutralization, is an important challenge for Original Equipment Manufacturers and end-users. Often the decline in Total Base Number (TBN) and increase in Total Acid Number (TAN) is measured during engine operation as an indication of the oil’s condition and lifetime. This is clearly an oversimplification given that no consideration is given to the type of acid, how corrosive it is, or the type of base and how effective it is at neutralizing. Acids can be broadly categorized into mineral acids such as sulfuric/nitric and organic acids such as acetic. Traditionally, research has focused on understanding the effects of mineral acids such as sulfuric, which can be formed during the combustion of sulfur-containing fuel.

Abstract Neutralization of acidic contaminants in engine lubricating oil is an important topic for engine manufacturers. Often, the deterioration in total base number (TBN) and increase in total acid number (TAN) during engine test operation is used as an indication of oil lifetime. This is clearly an oversimplification given that no consideration is given to how corrosive the acid is, and how effective the base is at neutralizing different acids. The work detailed here will explore how the presence of inorganic acids can be combated by lubricant additives, such as overbased detergents, through rapid neutralization. To achieve this, stopped-flow UV/visible spectroscopy has been used to measure the reaction kinetics between an overbased detergent and sulfuric acid containing water-in-oil (w/o) microemulsion droplets. The key structural properties of overbased detergents that contribute to effective acid neutralization will be explored.

Abstract We come across multiphase flow (oil and air) in many applications in automotive, aerospace, marine, chemical, and power grid industries. The present study presents a model that describes the flow of oil and air through an orifice from one chamber to another based on gravity, viscosity, and density difference. The aim of this study is to provide a simulation technique that finds the total time required for the complete percolation of oil/air to drain out from the respective chambers. This technique uses the Volume Of Fluid (VOF) using the Computational Fluid Dynamics (CFD) software STAR CCM+. VOF technique is a multiphase model and is very effective in determining the free-surface phenomenon. This technique uses an implicit unsteady and k-ε turbulence model at ambient conditions. Test results validate the CFD analysis. There is a good agreement between the simulation and test results.

Abstract An increase in the efficiency of internal combustion engines is a key challenge for engineers today. Mechanical losses contribute significantly to engine inefficiency, and the piston assembly has the largest share in these losses. Various measures are therefore taken to reduce friction between the piston and the rings against the cylinder. However, the undertaken changes most frequently generate new challenges. For instance, lowering the viscosity of the engine oil or increasing the engine load may lead to accelerated wear of the mating surfaces. In order to resolve this problem, more and more complex materials and anti-wear coatings have to be used. Furthermore, under these conditions, the shape of the ring’s sliding surface becomes more important. This article presents the results of experimental research on the influence of the geometry of the sliding surface and the use of various anti-wear coatings.

Abstract To improve the lubrication and friction of the crankpin bearing (CB) in the engine, the design of surface textures on the bearing surface is proposed and researched based on the CB hydrodynamic dynamic model. To enhance the reliability of the research results and its closeness to reality, the optimal CB parameters, the experimental data of the external dynamic load W0 acting on the crankpin, and the CB surface roughness in the well-known existing researches are referred to as input data for the simulation process. The effect of the distribution density {n, m}, diameter D, and depth of the microcircular textures hd on improving the lubrication and friction are then analyzed based on the indexes of the increase in the oil film pressure, decrease in the solid asperity contacts in the mixed lubrication region (MLR), friction force, and coefficient of friction (COF) between the crankpin and bearing surfaces, respectively.

Abstract Piston internal combustion engines used in the propulsion of ultralight aircraft are characterized by special operating conditions, especially an increased engine oil temperature. Most of the engines intended for the drive of the propeller drivetrain are air cooled. Failure to introduce an additional cooling agent so as to absorb and remove heat from the running engine makes the average lubricating oil temperature rise to about 140°C in the pistohn ring part. With such a thermal load, changes in the moments of resistance to motion of the engine are difficult to determine in the conditions of engine tests due to difficulties in temperature stabilization. The performance of aircraft engines requires taking into account many variables that are difficult to determine, which may affect changes in the moment of resistance to movement of the engine, especially when using oils of low dynamic viscosity.

Abstract The greatest frictional contributor in an internal combustion engine is the contact between the piston ring pack and cylinder liner. Therefore, an improved lubrication regime has the potential to raise engine efficiency while lowering emissions, aiding to meet environmental regulations. Previous ultrasonic measurements of the oil film thickness (OFT) between piston rings and the cylinder liner in a marine engine have been subject to several unexpected trends. This article refines the measurement to identify and remove these factors, the trends were found to have arisen due to the detection of ultrasonic reflections from the piston ring outside of the expected alignment zone. The extent of these undesired reflections is thought to be due to the liner thickness providing a relatively large distance for spreading of the ultrasonic wavefront.

Abstract The lubricating properties of diesel are an imperative aspect for the optimal functioning of fuel injection components. Regulatory standards followed by refineries utilize accelerated wear testing methodologies. These tests provide indicative results for judging the lubricity but are not conclusive for determining wear in functional applications attributed to higher loads and other environmental factors. In the course of this article, a tribological evaluation was carried out on Low-Sulfur Diesel (LSD) and Ultralow Sulfur Diesel (ULSD) by utilizing modified test parameters incorporating higher loads and a more extensive gradient of temperature on High-Frequency Reciprocating Rig (HFRR) tribotester. The variance in the resultant coefficient of friction (COF) and wear scar concerning the change in parameters was observed as well as a comparative analysis was drawn between both test fuels.

Abstract Low-Speed Pre-Ignition (LSPI) events occur in highly boosted direct-injected gasoline engines when operating at a low-speed and high-load region. The LSPI event appears once per several thousand cycles; once happening, it could last for a few cycles and suddenly returns to normal combustion. These features are coincident with intermittent lubricating oil piston crown scattering behavior, which experiences accumulation and heavy scattering. In this work, the theory originally proposed by Bradley to classify the auto-ignition propagation modes triggered by hot spots is developed to be capable of analyzing the reaction front propagation generated from the lubricating oil clouds, where the auto-ignition is induced by a reactivity gradient. A critical condition related to the interaction between the reaction and acoustic waves is defined with respect to the density gradient that characterizes the oil clouds.

Abstract Possible oil contamination of aircraft bleed air is an ongoing operational issue for commercial aircraft. A sensitive and reliable method to detect contamination, especially at very low levels, has been elusive due, in part, to the lack of information about the physical nature of oil that results when entrained in the bleed air by an engine compressor. While it was expected that high shear rates in the compressors would result in very finely dispersed particles, detailed data on the size characteristics of these droplets were not available, making it difficult to develop reliable detection techniques. The goal of the reported research was to collect experimental data to provide this information. The concentration and size distribution of particles were measured for bleed air with different rates of controlled oil contamination under various engine operating conditions.

Abstract The purpose of this article is to study the antifriction and anti-wear effect of GCr15 bearing steel under paraffin base oil and the base oil with two additives of T405 sulfurized olefin and nano-MoS2 and compare the synergistic lubrication effect of two different additives (MoS2 and T405) in paraffin base oil. The tribological properties of GCr15 bearing steel under different lubrication conditions were tested on a ball-on-disk tribometer. The three-dimensional profile of disk’s worn surfaces and the scanning electron microscope (SEM) micrographs of corresponding steel balls were analyzed at the same time. The wettability of lubricating oils on the surface of friction pairs and the dispersibility of MoS2 in base oil were characterized.

Abstract The global drive to combat climate change is a primary driving force towards producing greener and cleaner marine diesel engines to meet emission legislations. The main cause of an engine’s parasitic frictional loss is the interaction between piston rings and the cylinder liner. Therefore, the piston ring lubricating oil film has been the focus of much prior research, chiefly focusing on small-scale automotive engines. This work employs the ultrasonic reflectometry technique to evaluate the oil film formation resulting from different lubricant injector arrangements on a large two-stroke marine diesel engine. A series of piezoelectric transducers close to the top dead center (TDC) have quantified the oil film thickness (OFT) across three engine loading levels and three injector configurations. The injector configurations compare a more traditional pulse-jet (PJ) injector to a needle lift-type (NLT) injector, which reduces the rate of lubricant atomization.

Abstract Reaching the particle emissions regulatory limits for the combustion engine is a challenge for developers. Particle filters have been the standard solution to reduce particle emissions, but filters are limited in storage capacity and need to be regenerated, a process emitting more carbon dioxide (CO2) as more fuel is consumed to regenerate the filter. In previous research, it was found that the engine can emit large spikes in particle numbers (PNs) under stationary operating conditions. These spikes were several orders of magnitude higher than for the base particle emissions level and occurred seemingly at random. The source of the spikes was believed to be the cylinder-piston-ring system and as 50–99% of the particles stemmed from these spikes, the influence on the particle emissions made it an interesting investigation to find the root cause of it. The experiments were performed for different piston ring loads, locked ring positions, and different oil compositions.

Abstract Lubrication has been a major area of interest in engineering. Especially in vehicle transmissions, lubrication plays a very crucial role because gears and bearings are constantly subjected to heavy loads. Proper lubrication is essential for maintaining system performance and ensuring endurance life. Insufficient lubrication can lead to excessive wear, increased friction, and eventually, failures in the transmission components. However, excess lubrication can result in power losses due to the resistance offered by the excessive lubricant. Therefore, achieving effective lubrication using optimized lubrication system design is vital for ensuring the longevity and efficiency of the transmission system. Majorly, two types of lubrication methods are used in transmissions: splash lubrication and forced lubrication. This article focuses on forced lubrication, where the lubrication system actively delivers the required flow of lubricant to specific locations within the transmission.

Abstract The design of cylinder liners, pistons, and piston rings is subject to different conflicting goals. In addition to a loss-free seal of the combustion chamber, sufficient oil must be present between the friction partners. Both the reduction of piston assembly friction and the minimization of oil consumption are crucial to achieve the strictly defined CO2 and emission standards. To master this challenge and find the best compromise requires a lot of system-specific know-how. The automobile and engine manufacturers focus mainly on friction-reducing measures, which are analyzed with different measuring methods such as the floating-liner method, the strip-down method, or the instantaneous indicated mean effective pressure (IMEP) method. However, the interpretation of the results and the development of realistic simulation models lacks information about the oil film behavior and the film thickness.

Abstract The purpose of this study is to examine the phenomenon of Dynamic Particle Generation in lubricating greases that are used in a variety of critical Aerospace mechanisms. Particle Generation occurs in bearings, ball screws, and other mechanical devices where dynamic conditions are present. This should not be confused with outgassing as particle generation is unrelated to the pressure effects on a system. This is a critical factor in many systems as particle generation can contaminate systems or processes causing them to fail. These failures can lead to excessive costs, production failure, and equipment damage. In this study, several greases made from Multiplyalkylated Cyclopentane and Perfluoropolyether base fluids were tested to evaluate their particle generation properties. This particle generation phenomenon was studied using a custom test rig utilizing a high precision cleanroom ball-screw to simulate true application conditions.