Oil Jet Research Articles

ВПЛИВ УМОВ РОБОТИ НА ТЕМПЕРАТУРНИЙ РЕЖИМ ПІДШИПНИКІВ З МЕТАЛЕВИМИ ТА КЕРАМІЧНИМИ КУЛЬКАМИ

The results of an experimental study of the temperature mode of operation of rolling bearings under different lubrication conditions are presented. Comparative tests of all-metal bearings and similar bearings with rolling elements made of silicon nitride (hybrid bearings) when lubricated with an oil jet and an oil-air mixture in the range of rotor rotation frequencies from 0 to 35000 rpm were carried out. For the experiments, a specially created set was used, which allows you to study the temperature of the bearings and the temperature of the lubricant at the entrance and exit from the bearings. The axial load on the bearings was created with the help of a compression spring, which rested on the outer rings of the bearings. This made it possible to close the load inside the system. During the tests, the load was 0 N, 1000 N, and 2000 N. Tests were carried out for two modes of bearing lubrication: oil jet and oil-air mixture. The method of measuring the temperature of the outer ring of bearings is described. The temperature measurement error was considered as a complex of instrumental error and method error. It was assumed that the temperature error is subject to a normal distribution. The conducted analysis showed that the error of measuring the temperature of the bearing ring was ± 2.8 °C with a confidence probability of 95 %. It has been established that bearings with ceramic balls in the entire studied range behave qualitatively and quantitatively in approximately the same way as with steel ones. The temperature level of hybrid bearings is slightly higher when lubricated with both an oil jet and an oil-air mixture. There is a clear connection between the values of the bearing temperature and the moment of resistance in the bearing: the increase in temperature is observed under the same conditions under which the moment of resistance increases.

Estimation of Piston Surface Temperature During Engine Transient Operation for Emissions Reduction

Abstract Piston surface temperature is an important factor in the reduction of harmful emissions in modern gasoline direct injection (GDI) engines. In transient operation, the piston surface temperature can change rapidly, increasing the risk of fuel puddling. The prediction of the piston surface temperature can provide the means to significantly improve multiple-pulse fuel injection control strategies through the avoidance of fuel puddling. It could also be used to intelligently control the piston cooling jet (PCJ), which is common in modern engines. Considerable research has been undertaken to identify generalized engine heat transfer correlations and to predict piston and cylinder wall surface temperatures during operation. Most of these correlations require in-cylinder combustion pressure as an input, as well as the identification of numerous model parameters. These requirements render such an approach impractical. In this study, the authors have developed a thermodynamic model of piston surface temperature based on the global energy balance (GEB) methodology, which includes the effect of PCJ activation. The advantages are a simple structure and no requirement for in-cylinder pressure data, and only limited experimental tests are needed for model parameter identification. Moreover, the proposed model works well during engine transient operation, with maximum average error of 6.68% during rapid transients. A detailed identification procedure is given. This and the model performance have been demonstrated using experimental piston crown surface temperature data from a prototype 1-liter 3-cylinder turbocharged GDI engine, operated in both engine steady-state and transient conditions with an oil jet used for piston cooling turned both on and off.

Heat transfer on impingement cooled meshing spur gears: Experimental comparison of into-mesh, out-of-mesh and inclined impingement methods

Oil jet impingement cooling is the standard approach to cool high-speed high-power gears. The heat transfer between oil jets and gears is experimentally investigated in this paper. The three established methods of oil jet impingement cooling -into-mesh, out-of-mesh and inclined impingement on one of the gears- are studied. Heat transfer coefficients for these methods are experimentally determined. A loss correction approach is implemented for the evaluation of measurements. For the inclined impingement method, heat transfer on the non-impinged gear and the influence of meshing on the heat transfer coefficient are investigated. Gear meshing has an insignificant effect on the average heat transfer coefficient over the gear tooth. However, the spatial distribution of the heat transfer coefficient depends on the meshing configuration. Significant cooling on the non-impinged gear is observed with the inclined impingement method. The inclined impingement method is superior to the into-mesh and out-of-mesh methods at all measured operating points.

The Enhancement of Oil Delivery and Bearing Performance via a Guiding-Structured Nozzle under Oil–Air Lubrication

The oil–air lubrication method is specifically employed for high or ultra-high-speed spindle rolling bearings. Under high-speed conditions, the air curtain formed inside the bearing cavity obstructs oil delivery, thereby limiting further increases in spindle rotation speed. To enhance oil delivery capability, a guiding-structured nozzle has been developed to concentrate the jet flow and improve penetration through the air curtain. Tests were conducted on an oil–air lubricated bearing test bench to investigate the impact of nozzle structures and oil types on torque and temperature rise. The results demonstrate that compared to conventional nozzles, the guiding-structured nozzle requires smaller optimal amounts of oil supply, indicating its superior ability to deliver oil. Further examination of oil jet patterns and droplet distributions confirms that the guiding-structured nozzle provides a more concentrated jet flow with uniform distribution and smaller droplet sizes in diameter. These characteristics contribute to highly efficient oil delivery. Additionally, synthetic oils reduce droplet size, torque, and temperature rise in mixed lubrication regimes due to their formation of an anti-friction absorption layer on rubbing surfaces.

Experiment and Simulation Study on the Cooling Performance of Oil-Cooling PMSM with Hairpin Winding

In this paper, the cooling performance of oil-cooling PMSM with hairpin winding under various oil parameters is analyzed via a simulation and an experiment. The effects of oil jet positions, oil temperatures, and oil flow rates on the cooling performance are analyzed. It is found that increasing the oil temperature in the range of 20 °C to 60 °C, increasing the flow rate of oil jets whose position angle is from 15° to 45°, and increasing the flow rate in the range of 1 L/min to 2 L/min will significantly improve the cooling performance. The apertures of the oil spray ring are optimized using the Taguchi algorithm. The cooling performance is the best when the flow ratio is m(0°):m(15°):m(30°):m(45°):m(60°):m(75°) = 4%:19%:10%:10%:4%:4%. This study provides a guide for the design of the oil-cooling system for the hairpin winding of the PMSM.

Transient Simulation Analysis of Needle Roller Bearing in Oil Jet Lubrication and Planetary Gearbox Lubrication Conditions Based on Computational Fluid Dynamics

The transient lubrication conditions of rolling bearings are different in gearboxes and bearing testers. It has been observed that samples of qualified rolling bearings tested in rolling bearing testers often fail and do not meet lifespan requirements when employed in other lubrication conditions. This may be caused by different factors affecting the bearing in testing and applying lubrication. Needle roller bearings were selected for this study to investigate the causes of this phenomenon in terms of lubrication. Based on the computational fluid dynamics (CFD) method, fluid domain models for the same type of rolling bearings with different lubrication conditions were established. The transient flow fields of rolling bearings with oil jet lubrication in a tester and splash lubrication in a planetary gearbox were simulated. The air–oil transient distribution of rolling bearings in two kinds of lubrication was analyzed. The results indicate that the rotational speed significantly affected the oil jet lubrication of the needle roller bearing. The average oil volume fraction rose by 0.2 with the increase in the bearing speed from 1200 r/min to 6000 r/min and by 0.06 with the increase in the oil jet velocity from 8 m/s to 16 m/s. The splash lubrication of the bearings in the planetary gearbox was directly related to the immersion depth of the rolling bearings in the initial position. Meanwhile, the splash lubrication of the bearings was also affected by other factors, including the initial layout of the planetary gears. The increase in speed from 1200 r/min to 6000 r/min made the average oil volume fraction of splash lubrication decrease by 4.4%. The average oil volume fraction of the bearings with splash lubrication was better than that with oil jet lubrication by an average of 41.9% when the bearing speed was in the low-speed stage, ranging from 1200 r/min to 3600 r/min. On the contrary, the bearings with oil jet lubrication were better than those with splash lubrication by an average of 31.8% when the bearing speed was in the high-speed stage, ranging from 4800 r/min to 6000 r/min.

Flow Characteristics of Liquid Jet in Transverse Shear Crossflow

The numerical simulation method was used to investigate the deflection and deformation process of a circular lubricating oil jet in transverse shear airflow. The numerical model was compared and validated against the experimental data. The physical parameters of Mobil jet Oil II were utilized in this simulation with the nozzle diameter ranging from 0.5 to 2.5 mm, the maximum liquid/gas momentum ratios varying from 10.35 to 165.50, and the injection angle ranging from 0 to 30° in the opposite airflow direction. The results show that an increase in the nozzle diameter decreases the degree of jet deflection. The higher airflow velocity causes more fluctuations in the oil-jet trajectory, while the higher oil-injection velocity reduces fluctuations in the trajectory. The parabolic curve equations were used to derive the trajectory equations for the jet column’s pre-disintegration under both vertical incidence and a small angle of reverse airflow. The nozzle diameter and maximum oil/air momentum ratio were used to obtain a formula for the trajectory curve of the lubricating oil. Additionally, a formula for fitting the trajectory curve of oil injected in the opposite airflow direction regarding the injection angle was developed.

Power Loss Analysis of an Oil-Jet Lubricated Angular Contact Ball Bearing: Theoretical and Experimental Investigations

This study presents a theoretical and experimental analysis to quantify the power losses generated by an oil jet lubricated angular contact ball bearing. The analysis is conducted for a moderate speed range (N∙dm product less than 106) and a limited applied load (<5% of the static capacity). The lubrication regime of each ball is studied through a theoretical model and varies from Iso-Viscous Rigid to Elasto-Hydrodynamic. Therefore, the hydrodynamic effects are considered in the power loss calculation. An experimental campaign is carried out and the influence of several parameters (applied load, oil injection temperature, speed, etc.) is studied. A good agreement is found between the developed model and the measurements. It is shown that the radial applied load has no influence on power losses, unlike speed and axial load. This can be explained by the load distribution and the hydrodynamic rolling contribution on the low loaded balls.

The Impact of Motive Nozzle Spacing and Surface Roughness on The Performance of Axial Water- Oil Jet Pumps in an Egyptian Offshore Oil Field: An Experimental and Computational Investigation

The Impact of Motive Nozzle Spacing and Surface Roughness on The Performance of Axial Water- Oil Jet Pumps in an Egyptian Offshore Oil Field: An Experimental and Computational Investigation

Effect of Outlet Shape on Flame Height of Transformer Oil Jet Fire Under External Fire Source

Abstract In this inquiry, we delve into the manner by which disparate orifice configurations exert influence upon the elevation of the jet flame when subjected to an external conflagration, employing empirical simulations. Elaborating upon the empirical dataset, we introduce the derivative of hydraulic diameter alterations and the velocity of material degradation, thereby revising the traditional non-dimensionalized model of flame altitude. The revelations disclose that, across an array of orifice profiles, the conflagration jet within oil-laden apparatus undergoes four discernible phases of evolution, each replete with variable flambeau altitudes. In disparate operational circumstances, the quantified velocity of material degradation during the evolution phase manifests an exponential interrelation with the approximated value of the model. Conversely, the phases of stability and decline adhere to a potency function connection. A quantitative delineation of the pivotal states for each phase of combustion is achieved through the evaluation of the rate of alteration in the velocity of material degradation. Significantly, the pivotal juncture for the proliferation and equilibrium stage is ascertained to be 2 g/s. This scientific inquiry confers invaluable theoretical reinforcement for fire safeguarding and catastrophe evaluation within substations accommodating oil-infused apparatus.

Numerical and Experimental Investigations to Assess the Impact of an Oil Jet Nozzle with Double Orifices on the Oil Capture Performance of a Radial Oil Scoop

To study the influence of orifice spacing on the oil–air two-phase flow and the oil capture efficiency of an oil scoop in an under-race lubrication system, an experimental platform for under-race lubrication was built, and a calculation model for the oil–air two-phase flow field was established. The rationality of the experiment and the validity of the numerical model were verified by comparing the experimental and numerical results. The results showed that under the same oil supply pressure, the captured oil mass flow rate of the double-orifice structure was much higher than that of the single-orifice structure, though it was still less than twice that of the single-orifice structure. When applying a tandem layout structure of double orifices to an under-race lubrication system, the orifice spacing of the tandem layout structure should be determined based on a full evaluation of the influence of the orifice spacing and working condition parameters on the oil capture performance. Otherwise, it may lead to a decrease in oil capture efficiency, with the maximum reduction even reaching 12%.

Self-driven oil/water separator with super-high separation rate

Oil/water separation is of great significance due to the severe threats of oily wastewater to the environment and human health. However, the existing methods still cannot spontaneously and continuously separate the oil/water mixture with high rates and low costs. Here, a novel oil/water separation method based on a self-driven oil jet phenomenon was proposed to resolve the aforementioned problem. We designed a self-driven oil/water separator (SOWS) composed of an oil container with some oil and a water container with some water. The oil container, whose whole bottom was covered with underwater superoleophilic pores, underwater superoleophilic ring region, and other underwater superoleophobic region, was fixed in the water container. The underwater oil droplet was easily captured by the superoleophilic region and spontaneously penetrated the pore, generating an oil jet. The resultant force from Laplace pressure and hydrostatic pressure drove the droplet to generate the jet and affected the droplet flow rate. Based on the self-driven oil jet and suitable optimization, the SOWS realized the spontaneous and continuous oil/water separation with the separation rate of 42929.4 L∙m−2∙h−1 which was much faster than the reported oil/water separation methods. Moreover, the SOWS could efficiently separate the oil/water mixture with different oil content and oil viscosity. This method shows an outstanding practical application prospect in the oily wastewater treatment.

A New Experimental Methodology to Study Convective Heat Transfer in Oil Jet Lubricated Gear Units

The purpose of this study is to generate some experimental data associated with the thermal heat exchange between an oil jet flow and a rotating gear. To this end, a specific test bench was designed. The principle of this test bench is to inject oil heated to a temperature of about 80 °C onto a rotating test sample at ambient temperature. Temperature measurements of the oil via injection nozzles and the rotating component allow the determination of the heat flow between these elements using a numerical method developed to this end. This test rig enables the study of the parameters that may affect heat exchange, such as oil flow rate and injection temperature, nozzle geometry and position, gear rotational speed and tooth geometry, or oil characteristics. In this study, three of these parameters were investigated, namely the test sample rotational speed, the oil flow rate, and the oil jet velocity. The experiments were conducted on an aluminum disc and spur gear. Subsequently, the experimental results were compared with existing models that represent the convective exchanges between oil and a gear. Some discrepancies between existing models and experimental results appear at high rotational speeds, underlining that the convective heat transfer does not always increase with this parameter.

Research of the combustion process in a tractor diesel engine when operating on alcohol and vegetable oil

BACKGROUND:Tractor diesels are widely used in agriculture, industry and transport due to their high efficiency, reliability, manufacturability and economy. Nevertheless, the ever-increasing tractor fleet is one of the main causes of environmental pollution and the increase in the consumption of petroleum motor fuel. The paper substantiates the use of an alternative fuel, suitable in its physical and chemical characteristics and properties for efficient and environmentally friendly combustion in a tractor diesel, such as ethanol and rapeseed oil. AIMS:Research of the combustion process in a tractor diesel engine operating on ethanol and rapeseed oil, establishment the dependencies of the influence of tractor diesel operating modes on the combustion process indicators and determination of their numerical characteristics. METHODS:An experimental sample of a tractor diesel engine was converted for operation on ethanol and rapeseed oil. Ethanol was used as the main fuel and was ignited with a jet of rapeseed oil entering the diesel combustion chamber. Ethanol has a lower calorific value compared to diesel fuel, therefore, there was a need to determine the optimal cyclic supply of the ignition portion of rapeseed oil and to study the indicators of the combustion process. RESULTS:The results of experimental studies of the effect of the use of ethanol and rapeseed oil as a pilot fuel on the indicators of the combustion process of tractor diesel are presented. The optimal value of the cyclic supply of rapeseed oil has been determined, a decrease in the value of which from the optimal value leads to an increase in exhaust gas temperature, specific effective and total fuel consumption, worsens the combustion process, while an increase of it worsens the environmental performance of a tractor diesel engine, including the smokiness of exhaust gases. The results of scientific research on the determination of optimal installation angles of advance injection of ethanol and rapeseed oil are presented. CONCLUSIONS:The complete replacement of petroleum diesel fuel with alternative fuels has been achieved without making significant changes to the design of a tractor diesel engine, improving its environmental characteristics while maintaining power indicators at the level of a serial diesel. On the basis of the conducted studies of the operating process of a tractor diesel engine on ethanol and rapeseed oil, the dependencies of the influence of its operating modes on the indicators of the combustion process are established and their numerical characteristics are determined.

Advanced Lubrication Simulations of an Entire Test Rig: Optimization of the Nozzle Orientation to Maximize the Lubrication Capability

In the framework of the H2020 project IDERPLANE, aimed at providing innovative, effective, and validated criteria for the design and assessment of more reliable planet bearings for aerospace application analyzing the problem from a damage tolerance perspective, the present paper presents the numerical study and optimization of a test rig specifically designed for the experiments on the full-test article. Specifically, for the first time ever, an entire system including shafts, gears and bearings with all the rolling elements have been studied with a Finite Volume Computational Fluid Dynamics approach. This ambitious challenge was addressed with the implementation of a new mesh handling technique, namely the Global Remeshing Approach with Mesh Clustering (GRAMC). The aim was to optimize the lubrication of the test article to avoid unexpected failures during the experimental campaign. Three different oil jet directions have been studied and the most effective one, namely the axial one, was selected for the final test rig design.

Development of a Temperature Distribution Measurement System for Transmission Oil for Transportation Equipment

In this study, an optical sensor using thermo-sensitive phosphor and its measurement system for visualizing and measuring the temperature distribution in an arbitrary cross-section of transmission oil using one type of phosphor, whose peak wavelength changes with temperature, is proposed. Because the intensity of the excitation light is gradually attenuated by the scattering of the laser light owing to microscopic impurities in the oil, we attempted to reduce the scattering effect by increasing the excitation light wavelength. Therefore, Pyrromethene 597 was selected as the optical sensor using thermo-sensitive phosphor, and a DPSS (Diode Pumped Solid State) laser with a wavelength of 532 nm was used as the excitation light. Using this measurement system, we measured the temperature distribution of a vertical buoyant jet of transmission oil and validated the measurement method. In addition, it was shown that this measurement system could be applied to the measurement of the temperature distribution in transmission oil with cavitation foaming.

VORTEX CHAMBER PUMP CHARACTERISTICS DURING OIL PUMPING WITH DIFFERENT SUCTION PRESSURES

Improving the efficiency of oil pumping is an urgent and difficult task due to the significant variety of composition, physical properties and impurities that can enter the oil. Among the means of oil transportation, jet pumps and technologies are gaining popularity. Jet machines and devices have highreliability indicators due to the absence of moving bodies at low efficiency, which is associated with the energy transfer between jets, and vortex chamber superchargers stand out among other jet-type pumps by combining the positive qualities of centrifugal and jet pumps. The aim of the work is to determine the characteristics of vortex chamber pumps (VCP) during oil pumping with different conditions of oil suction. The study was carried out numerically by solving the Reynolds-averaged Navier-Stokes equations. The sensitivity analysis of the calculation results was carried out for three grids using the Shear Stress Transport (SST) turbulence model. For the first time, on the basis of analytical studies, the dependences of changes in the main integral parameters of the VCP operation efficiency on the gauge pressure in the suction channel were obtained. Increasing the suction gauge pressure allows to increase the maximum suction flow rate by 44 %, and the maximum relative efficiency by 14 %. Increasing the pressure in the suction channels reduces the relative effective pressure at the pump outlet by 30 %. There is a linear decrease in the relative effective pressure at the pump outlet in the absence of outlet static pressure. Also, there is an almost linear increase in suction flow rate, but with a greater angle of characteristic inclination, which leads to an increase in relative efficiency. Along with an increase in the efficiency of the VKN in comparison with a serial direct-flow jet pump, the linear overall size has been reduced by more than 3 times.

Generalized analytical model for evaluating the gear power losses transition changing from windage to churning behavior

Although splash lubrication is usually adopted in the intermediate or tail gearbox of helicopters at low or moderate speed, and it appears that the oil jet lubrication used in a high-speed main reducer of helicopters would be turned into the splash lubrication that only a small part of gears is immersed in the oil sump due to the lubricating oil deposition by the mismatch between the oil feed and return. The classic drag power losses model is either used for the churning behavior of common splash lubrication or the windage behavior of oil jet lubrication, and is no longer suitable for this transition phenomenon of these two behaviors coexist. In this paper, a theoretical analytical method by introducing the windage contribution factor and air-oil ratio evolution model is proposed to predict the associated power losses for one single spur gear rotating partially immersed in an oil bath. To verify the accuracy and correctness, the theoretical calculations are then compared with the existing experimental data from Quiban et al. [33]. Based on this method, a generalized analytical model to evaluate the gear drag power losses for the windage, churning phenomenon and their transition behavior are established.

Oil jets piston cooling: A numerical methodology for the estimation of heat transfer coefficients and optimization of the piston temperature field through a genetic algorithm

High-efficiency internal combustion engines need specific methodologies to be developed for the design improvement of the components. Predicting and reducing the thermal loadings on the parts are critical tasks to be addressed. This contribution focuses on the thermal management of the piston through oil jets. The operating temperature of the piston deeply affects its thermo-mechanical behavior, thus possibly jeopardizing the structural integrity of the component. The design of piston cooling jets is usually addressed through Computational Fluid Dynamics, which can guarantee accurate results, usually at a high computational cost. In this contribution, a faster tool is derived to grasp the effect of the cooling jets on the temperature of the piston. Empirical correlations are applied to predict the instantaneous heat transfer coefficients on the piston. The reciprocating motion of the piston is considered since it affects the interaction between the surface and the oil jets. Instantaneous coefficients are cycle-averaged and used to estimate the temperature of the piston through a Finite Element thermal analysis. Finally, an optimization code is developed to find the best jet configuration capable to minimize the temperature of the piston. This methodology is a powerful tool to select the optimal oil jet nozzles for piston cooling.

Microalgal Feedstock for Biofuel Production: Recent Advances, Challenges, and Future Perspective

Globally, nations are trying to address environmental issues such as global warming and climate change, along with the burden of declining fossil fuel reserves. Furthermore, countries aim to reach zero carbon emissions within the existing and rising global energy crisis. Therefore, bio-based alternative sustainable feedstocks are being explored for producing bioenergy. One such renewable energy resource is microalgae; these are photosynthetic microorganisms that grow on non-arable land, in extreme climatic conditions, and have the ability to thrive even in sea and wastewater. Microalgae have high photosynthetic efficiencies and biomass productivity compared to other terrestrial plants. Whole microalgae biomass or their extracted metabolites can be converted to various biofuels such as bioethanol, biodiesel, biocrude oil, pyrolytic bio-oil, biomethane, biohydrogen, and bio jet fuel. However, several challenges still exist before faster and broader commercial application of microalgae as a sustainable bioenergy feedstock for biofuel production. Selection of appropriate microalgal strains, development of biomass pre-concentrating techniques, and utilization of wet microalgal biomass for biofuel production, coupled with an integrated biorefinery approach for producing value-added products, could improve the environmental sustainability and economic viability of microalgal biofuel. This article will review the current status of research on microalgal biofuels and their future perspective.