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"Lubrication systems"
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All aboard! : Elijah McCoy's steam engine
Simple text and illustrations explore the life of inventor, Elijah McCoy. Includes explanation of the saying, \"The real McCoy.\"
Book
The Impact of the Lubricant Dose on the Reduction of Wear Dies Used in the Forging Process of the Valve Forging
The paper presents the results of research on the influence of the settings of lubrication and cooling system parameters (solenoid valve opening time and lubricant feed pressure in terms of its quantity) in order to select the optimal lubricating conditions and thus reduce the wear of the dies used in the first forging operation of the valve forging made of high-nickel steel. Based on the observation of lubrication in the industrial process, it was found that a significant part of the lubricant fails to reach the die cavity, reaching the outside of it, which causes die wear due to seizure resulting from adhesion of the forging material to the tool surface as well as high lubricant consumption and dirt in the press chamber. The authors proposed their own mobile lubricating and cooling system, which allows for a wide range of adjustments and provided with automatic cleaning procedures of the entire system, unlike the fixed lubrication system used so far in the industrial process. First, tests were carried out in laboratory conditions to determine the highest wettability and the lubricant remaining inside the tool cavity. These tests determined the lubrication system parameter settings that ensured that the greatest amount of lubricant remains in the cold die cavity without the forging process. Then, to verify the obtained results, tests were carried out in the industrial process of hot die forging of valve forgings for short production runs of up to 500 forgings. The results were compared with the measurement of changes in the geometry of tools and forgings based on 3D scanning and surface topography analysis with the use of SEM (Scanning Electron Microscope). For the best results (the variant of the setting of the dose and the time of exposure to lubricant), the forging process was carried out with the use of a new tool up to the maximum service life.
Journal Article
Computational analysis of air bubble-induced frictional drag reduction on ship hulls
About 60% of marine vessels’ power is consumed to overcome friction resistance between the hull and water. Air lubrication can effectively reduce this resistance and lower fuel consumption, and consequently emissions. This study aims to analyze the use of a gas-injected liquid lubrication system (GILLS) to reduce friction resistance in a real-world scenario. A 3D computational fluid dynamics model is adopted to analyse how a full-scale ship (the Sea Transport Solutions Designed Catamaran ROPAX ferry) with a length of 44.9 m and a width of 16.5 m is affected by its speed and draught. The computational model is based on a volume of fluid model using the k-ꞷ shear stress transport turbulence model. Results show that at a 1.5 m draught and 20 knots cruising speed, injecting 0.05 kg/s of compressed air into each GILLS unit reduces friction resistance by 10.45%. A hybrid model of natural air suction and force-compressed air shows a friction resistance reduction of 10.41%, which is a promising solution with less required external power. The proposed technique offers improved fuel efficiency and can help to meet environmental regulations without engine modifications.
Journal Article
Numerical and Experimental Investigations on Oil Supply Characteristics of a Multi-Passage Lubrication System for a Three-Stage Planetary Transmission in a Tracked Vehicle
The multi-passage lubrication system is adopted to meet the demand of the main heat generation parts (gears and bearings) in the three-stage planetary transmission system of a large tracked vehicle. As rotational speed increases, the flow regime inside the passages with multi-oil outlets becomes highly complex. Under high-speed conditions, the flow rate in Zone 2 decreases sharply, and some oil outlets even drop to zero, representing a 100% reduction amplitude, which results in an unstable oil supply for heat generation parts and even potential lubrication cut-off. In the present work, the lubrication characteristics of the oil supply system for the three-stage planetary transmission system are investigated by a combination of CFD (computational fluid dynamics) simulations and experiments. A complete CFD model of the multi-passage lubrication system is established, comprising a stationary oil passage, a main oil passage, and a three-stage variable-speed oil passage. A transient calculation method based on sliding mesh rotation domain control is used to simulate the oil-filling process in the oil passages, and the oil supply characteristics of the variable-speed oil passage are investigated. A test bench for the multi-stage planetary transmission system is designed and constructed to collect oil flow data from outlets of planetary gear sets. The comparison between simulated and experimental results confirms the validity of the proposed numerical method. Additionally, numerical simulations are conducted to investigate the effects of key factors, including input speed, oil supply pressure, and oil temperature, on the oil flow rate of outlets. The results indicate that the rotational speed is the major parameter affecting the oil flow rate at the oil passage outlets. This work provides a practical guidance for optimizing lubrication design in complex multi-stage planetary transmission systems.
Journal Article
Current carrying tribological properties of multi arc ion plated titanium nitride doped silver coating
Sliding electrical contact materials play a crucial role in the transmission and conversion of electrical energy, but due to various factors such as force, electricity, and heat, the interface exhibits complex wear behavior. A single solid or liquid lubrication system can no longer meet the growing performance requirements of current carrying tribology. In this study, a TiN-Ag coating was prepared using multi arc ion plating technology, and a solid–liquid composite lubrication system was formed with ionic liquid and polyurea grease, respectively. Through current carrying friction and wear tests, their tribological properties, electrical contact resistance(ECR) values, and stability were tested, and compared with the results obtained during dry friction. The coating and worn surfaces were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results indicated that compared with dry friction, TiN-Ag coatings lubricated with ionic liquids and polyurea grease showed higher friction reduction, wear resistance, and conductivity, especially the synergistic effect between ionic liquids and coatings is prominent. The behavior of ionic liquids under voltage was analyzed, and it was found that ionic liquids formed a physical adsorption film composed of a mixture of anions and cations on the worn surface. The ordered layered structure improved the tribological performance of the system.
Journal Article
Green-Emitting Carbon Quantum Dots: Highly Sensitive Temperature Sensing Probe in Nanocomposite and Lubrication System
Carbon quantum dots (CQDs) have already demonstrated their utility as lubricant additives, and non-contact temperature sensing based on CQDs offers considerable potential for condition monitoring in mechanical, electrical, and other fields, as well as lubrication-temperature multifunctional applications in lubricants. In this paper, we have successfully synthesized and designed high-brightness carbon quantum dots/polyvinyl alcohol (PVA) temperature sensor thin film and dispersions of CQDs in a liquid paraffin lubrication system. Based on fluorescence intensity and the fluorescence intensity ratio, the carbon quantum dot/PVA film exhibited exponential temperature-dependent properties with a wide applicability range, a high goodness of fit (R2 > 0.99), and high relative thermal sensitivity (relative sensitivities of 1.74% K−1 and 1.39% K−1 for fluorescence intensity and fluorescence intensity ratio, respectively). In addition, based on the fluorescence intensity, the CQDs exhibited a wide temperature range (20–90 °C), a high goodness of fit (R2 > 0.99), and higher sensitivity (2.84% K−1) in a liquid paraffin lubrication system, which reflects the temperature responsive properties of carbon quantum dots as additives in lubrication systems. These findings provide convenient and effective possibilities for the sensing and monitoring of carbon quantum dots and their multifunctional applications under lubrication systems.
Journal Article
Computational Analysis of Air Lubrication System for Commercial Shipping and Impacts on Fuel Consumption
Our study presents the computational implementation of an air lubrication system on a commercial ship with 154,800 m3 Liquified Natural Gas capacity. The air lubrication reduces the skin friction between the ship’s wetted area and sea water. We analyze the real operating conditions as well as the assumptions, that will approach the problem as accurately as possible. The computational analysis is performed with the ANSYS FLUENT software. Two separate geometries (two different models) are drawn for a ship’s hull: with and without an air lubrication system. Our aim is to extract two different skin friction coefficients, which affect the fuel consumption and the CO2 emissions of the ship. A ship’s hull has never been designed before in real scale with air lubrication injectors adjusted in a computational environment, in order to simulate the function of air lubrication system. The system’s impact on the minimization of LNG transfer cost and on the reduction in fuel consumption and CO2 emissions is also examined. The study demonstrates the way to install the entire system in a new building. Fuel consumption can be reduced by up to 8%, and daily savings could reach up to EUR 8000 per travelling day.
Journal Article
Studying the Temperature Characteristics of Oil at the Outlet From the K27-145 Turbocharger Rotor Bearing
Turbocharging is a promising solution for increasing the specific power of motor-and-tractor equipment, which allows increasing power up to 50%. At the same time, a significant growth of speed, load, and temperature modes leads to a significant increase in the number of failures and a decrease in reliability by 2–3 times. Theoretical and experimental studies established that the temperature of the bearing and oil at the turbocharger drain changes under the influence of the inlet oil temperature to the TCR bearing, the TCR rotor shaft speed, and the change in the oil pressure at the input to the TCR bearing. This allows setting the limits of the TCR bearing performance in extreme operating conditions. The installation of an autonomous TCR lubricating and braking device maintains the required reliability level and increases failure-free operation. The hydraulic accumulator installed in the lubrication system of the engine turbocharger regulars lubricates and cools the rotor bearings when the ICE crankshaft speed drops. The incorporation of a braking device reduces the rundown time of the rotor and thereby prevents oil starvation and dry friction of the rotor bearing. The combined use of the hydraulic accumulator and the braking device minimizes the risk of dry friction and accidental failure of the turbocharger. We proved that the braking device of the TCR rotor built into the intake system of an ICE with the calculated design parameters reduces the rotor rundown time by 30–35%. This reduces the dimensions and operating time of the hydraulic accumulator and simultaneously eliminates surges in the compressor section of the TCR and any breakage of its parts. In these conditions, it is relevant to develop independent systems to lubricate the TCR bearings and replenish them using built-in hydraulic accumulators during start-up, significant loads at minimum crankshaft speeds, and engine stalling.
Journal Article
Efficiency and Sustainability Analysis of the Repair and Maintenance Operations of UNS M11917 Magnesium Alloy Parts of the Aeronautical Industry Made by Intermittent Facing
This paper analyzes the efficiency and sustainability of facing operations that are required within maintenance operations in the aeronautical industry. Due to the elevated cost and environmental impact of such processes, reducing the operating time while repairing parts is required. In this work, an experimental study of intermittent facing carried out on a magnesium alloy rod was developed. The experiment resembles real repair and maintenance machining operations, where an intermittent facing represents a more realistic scenario and where the results obtained in continuous turning studies are not always applicable. The work was performed with different cooling and lubrication systems and various cutting conditions, also considering the size of the interruption to analyze their impact in the surface roughness. To this end, surface finished in different measuring zones was studied. The aims of the study are to get a better understanding of the intermittent facing process in magnesium alloys typically employed in aeronautical applications and find the most efficient cutting parameters to obtain an improved surface under the safest and most environmentally respectful conditions.
Journal Article
Transient, Three Dimensional CFD Model of the Complete Engine Lubrication System
This paper reports on a comprehensive, crank-angle transient, three dimensional, computational fluid dynamics (CFD) model of the complete lubrication system of a multi-cylinder engine using the CFD software Simerics-Sys / PumpLinx. This work represents an advance in system-level modeling of the engine lubrication system over the current state of the art of one-dimensional models. The model was applied to a 16 cylinder, reciprocating internal combustion engine lubrication system. The computational domain includes the positive displacement gear pump, the pressure regulation valve, bearings, piston pins, piston cooling jets, the oil cooler, the oil filter etc… The motion of the regulation valve was predicted by strongly coupling a rigorous force balance on the valve to the flow. The results show that the majority of the system pressure drop and flow rates occur in bearings, lifters and piston cooling jets, confirming the importance of a three-dimensional treatment for these components versus a relatively empirical zero or one-dimensional treatment. The newly developed CFD capability is timely because it can also drive the development of system-level models in adjacent design areas of topical interest such as engine oil warm up, interaction between lube oil and coolant temperatures, engine oil temperature distribution (which can impact oil life), uncovering of oil pick up tube, oil pump priming, bearing cavitation and dry spots, oil aeration, piston cooling jets, variable displacement vane pump and other related topics.
Journal Article