DLC-coated spur gears – part I: friction reduction

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Andreas Schwarz ◽  
Martin Ebner ◽  
Thomas Lohner ◽  
Karsten Stahl ◽  
Kirsten Bobzin ◽  
...  
Keyword(s):  
Thermal Insulation ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Experimental Investigations ◽  
Bulk Temperature ◽  
Test Rig ◽  
Dlc Coatings ◽  
Content Type ◽  
Temperature Reduction ◽  
Insulation Effect

Purpose This paper aims to address the influence of diamond-like carbon (DLC) coatings on the frictional power loss of spur gears. It shows potentials for friction and bulk temperature reduction in industrial use. From a scientific point of view, the thermal insulation effect on fluid friction is addressed, which lowers viscosity in the gear contact due to increasing contact temperature. Design/methodology/approach Thermal insulation effect is analyzed in detail by means of the heat balance and micro thermal network of thermal elastohydrodynamic lubrication contacts. Preliminary results at a twin-disk test rig are summarized to categorize friction and bulk temperature reduction by DLC coatings. Based on experiments at a gear efficiency test rig, the frictional power losses and bulk temperatures of DLC-coated gears are investigated, whereby load, speed, oil temperature and coatings are varied. Findings Experimental investigations at the gear efficiency test rig showed friction and bulk temperature reduction for all operating conditions of DLC-coated gears compared to uncoated gears. This effect was most pronounced for high load and high speed. A reduction of the mean gear coefficient of friction on average 25% and maximum 55% was found. A maximum reduction of bulk temperature of 15% was observed. Practical implications DLC-coated gears show a high potential for reducing friction and improving load-carrying capacity. However, the industrial implementation is restrained by the limited durability of coatings on gear flanks. Therefore, a further and overall consideration of key durability factors such as substrate material, pretreatment, coating parameters and gear geometry is necessary. Originality/value Thermal insulation effect of DLC coatings was shown by theoretical analyses and experimental investigations at model test rigs. Although trial tests on gears were conducted in literature, this study proves the friction reduction by DLC-coated gears for the first time systematically in terms of various operating conditions and coatings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0257/

Experimental Study of Water Flow in Full-Size Test Rig for Water-Cooled Turbo-Generator Rotor

1966 ◽  
Vol 181 (1) ◽  
pp. 53-73 ◽  
Author(s):  
I. K. Csillag
Keyword(s):  
Operating Conditions ◽  
Experimental Investigations ◽  
Air Cooling ◽  
Test Rig ◽  
Full Size ◽  
Generator Rotor ◽  
Turbo Generator ◽  
Hydrogen Cooling ◽  
Major Factors ◽  
Design And Manufacture

The demand for electric power has doubled in the last decade. The most economical way to meet this demand is by building large-output generating units. The study of the major factors which determine the output of such generators shows that the only effective way to increase the output is by improving the cooling of their windings. For that reason design has progressed from air-cooling to indirect hydrogen-cooling, then to direct hydrogen-cooling. Now the trend is towards direct water-cooling where the water is in direct contact with the copper windings. The introduction of water into the stator winding was established in 1956 (1)† and was in fact directly responsible for the present increase in unit rating. The introduction of water to a rotating winding presents difficult problems in both design and manufacture. The test rig dealt with in this paper was built to study some of these problems and to carry out experimental investigations on a full size model of the special hydraulic features for a water-cooled turbo-generator rotor. The investigations were concentrated around the following five different problems which are dealt with in detail: (1) increase in pressure drop due to rotation; (2) free-rotating seal (inlet seal) (2); (3) vacuum-breaking device (water outlet) (3); (4) loss-distribution in the rotor; (5) measurement of the rotor vibrations in various operating conditions.

Performance studies of textured race ball bearing

2019 ◽  
Vol 71 (9) ◽  
pp. 1116-1123 ◽  
Author(s):  
Vivek Bhardwaj ◽  
R.K. Pandey ◽  
V.K. Agarwal
Keyword(s):  
Ball Bearing ◽  
Dynamic Performance ◽  
Critical Role ◽  
Operating Conditions ◽  
Frictional Torque ◽  
Bulk Temperature ◽  
Back Side ◽  
Ball Bearings ◽  
Content Type ◽  
Long Duration

Purpose The purpose of this paper is to develop an energy-efficient and dynamically improved thrust ball bearing using textured race. A texture has been used on the stationary race of the test bearing to conduct the long-duration experiment for exploring its tribological and vibrational behaviours under starved lubricating condition using micro size MoS2 blended grease. The performance behaviours of the textured race bearing have been compared with conventional bearing (i.e. having both races without textures) under the identical operating conditions for demonstrating the advantages of textured race. Design/methodology/approach Texture was created on stationary race of the test ball bearing (51308) using nano-second pulsed Nd: YAG laser. Performance parameters (frictional torque, temperature rise and vibrations) of textured ball bearings were measured under severe starved lubricating conditions for understanding the critical role of texture in the long duration of the test. S-type load cell and miniature accelerometer were used for measuring the frictional torque and vibration, respectively. Bulk temperature at stationary races (at the back side) of test bearings was measured in operating conditions using a non-contact infrared thermometer. Findings Significant reduction in frictional torque and decrease in amplitude of vibration with textured ball bearing were found even under the severe starved lubricating condition in comparison to conventional bearing. Originality/value There is dearth of research pertaining to the performance behaviours of ball bearings using textures on the races. Therefore, an attempt has been made in this study to explore the tribo-dynamic performance behaviours of a thrust ball bearing using a texture on its stationary race under severe starved lubricating condition for the longer duration of the test.

Multi-scale surface patterning – an approach to control friction and lubricant migration in lubricated systems

2019 ◽  
Vol 71 (8) ◽  
pp. 1007-1016 ◽  
Author(s):  
Philipp G. Grützmacher ◽  
Andreas Rosenkranz ◽  
Adam Szurdak ◽  
Markus Grüber ◽  
Carsten Gachot ◽  
...  
Keyword(s):  
Laboratory Tests ◽  
Journal Bearing ◽  
Friction Reduction ◽  
Patterned Surfaces ◽  
Test Rig ◽  
Content Type ◽  
Multi Scale ◽  
Surface Patterns ◽  
Lubricant Migration ◽  
Scale Surface

Purpose The paper aims to investigate the possibilities to control friction in lubricated systems by surface patterning, making use of a multi-scale approach. Surface patterns inside the tribological contact zone tend to directly reduce friction, whereas surface patterns located in the close proximity of the contact area can improve the tribological performance by avoiding lubricant starvation and migration. Finally, optimized surface patterns were identified by preliminary laboratory tests and transferred to a journal bearing, thus testing them under more realistic conditions. Design/methodology/approach Surface patterns on a large scale (depth > 10 µm) were fabricated by micro- and roller-coining, whereas surface patterns on a small scale (depth < 2 µm) were produced by direct laser interference patterning. The combination of both techniques resulted in multi-scale surface patterns. Tribologically beneficial surface patterns (verified in ball-on-disk laboratory tests) were transferred onto a journal bearing’s shaft and tested on a special test-rig. To characterize the lubricant spreading behavior, a new test-rig was designed, which allowed for the study of the lubricant’s motion on patterned surfaces under the influence of a precisely controlled temperature gradient. Findings All tested patterns accounted for a pronounced friction reduction and/or an increase in oil film lifetime. The results from the preliminary laboratory tests matched well, with results from the journal bearing test-rig, both tests showing a maximum friction reduction by a factor of 3-4. Numerical investigations, as well as experiments, have shown the possibility to actively guide lubricant over patterned surfaces. Smaller periodicities, as well as greater structural depths and widths, led to a more pronounced anisotropic spreading and/or greater spreading velocities. Multi-scale surfaces demonstrated the strongest effects regarding the lubricant’s spreading behavior. Originality/value Friction, as well as lubricant migration, can be successfully controlled by using micro-coined, laser-patterned and/or multi-scale surfaces. To the best of the authors’ knowledge, the study demonstrates for the first time the unique possibility to transfer results obtained in laboratory tests to a real machine component.

scholarly journals Design and Testing of a 10KW Steam Turbine for Steam Turbochargers

1985 ◽  
Author(s):  
M. Rautenberg ◽  
M. Malobabic ◽  
A. Mobarak ◽  
M. Abdel Kader
Keyword(s):  
Waste Heat ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Exhaust Gas ◽  
Test Rig ◽  
Pelton Turbine ◽  
Partial Admission ◽  
Turbine Design ◽  
Design And Testing

A Clausius-Rankine-cycle has been proposed to recover waste heat from a piston engine. This waste heat is then used to supercharge the cylinders by means of a steam turbocharger. The advantage of using this steam turbocharger system is to avoid the losses due to the engine back pressure which accompany the use of the conventional exhaust gas turbocharger. The mass flow rate of turbines for steam turbochargers in the range from 1 to 10 kW is about 0.03 to 0.08 kg/s. This implies a special turbine design, characterised by partial admission and supersonic flow, which unfortunately leads to low turbine efficiencies. A small Pelton turbine for steam has been designed and produced. The turbine is connected to the radial compressor of a conventional exhaust gas turbocharger which works, in this case, as a brake to dissipate the generated turbine power. A special test rig has been built to carry out the experimental investigations on the proposed Pelton turbine. The test rig is supplied with superheated steam from the University’s power plant. Two different rotors for this Pelton turbine have been tested under the same operating conditions (rotor 2 see Fig. 1). Some experimental test results of a special Pelton turbine are presented and discussed in this report.

Evaluation of a New Design Concept for a Ceramic Flame Tube Under Engine Conditions

1996 ◽  
Author(s):  
S. Münz ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Gas Turbine ◽  
Thermal Load ◽  
Operating Conditions ◽  
Design Concept ◽  
Experimental Investigations ◽  
Test Bed ◽  
Test Rig ◽  
Ceramic Structure ◽  
Flame Tube ◽  
Design Concepts

At the Institut für Thermische Strömungsmaschinen in Karlsruhe new design concepts for thermally high-loaded ceramic gas turbine components were developed. The present concept is based on a load-oriented segmentation in combination with a flexible suspension and thermal insulation of the ceramic structure. The concept was applied to a flame tube for a small gas turbine. In order to ensure real operating conditions, a Klöckner Humboldt Deutz T216 type gas turbine was used as test bed for the ceramic combustor. The paper gives a description of the combustor and the test rig. Furthermore, experimental results of the engine tests with special emphasis on the liner wall temperature distribution for various steady and transient operating conditions are presented. A major result of the tests is that the design concept proved to be reliable under real engine conditions. After more than 100 hours no failure of the ceramic parts occured. In order to determine the thermal load of the ceramic flame tube under real conditions, the experimental investigations are supported by numerical calculations.

Experimental and numerical investigation on single dent with marginal bump in EHL point contacts

2017 ◽  
Vol 69 (5) ◽  
pp. 798-807
Author(s):  
Xue-feng Wang ◽  
R.F. Hu ◽  
Weiyan Shang ◽  
Fuzhou Zhao
Keyword(s):  
Applied Load ◽  
Surface Defects ◽  
Contact Region ◽  
Point Contact ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Point Contacts ◽  
Content Type ◽  
Entrainment Velocity ◽  
Static Conditions

Purpose The dent is one of typical surface defects on the surfaces of the machine elements and it is not in fact inerratic. This work aims to investigate the effect of a single dent with a marginal bump on the film shape in elastohydrodynamic lubrication (EHL) point contacts. Design/methodology/approach The experimental investigations of a single dent with marginal bump were carried out using multi-beam interferometry in EHL point contacts. In the meantime, its numerical simulation was also finished using multi-level method and multilevel multi-integration method. The effects of the entrainment velocity and the applied load as well as the slide-roll ratio on the film were chiefly discussed. Meanwhile, the comparison of films between smooth and dented surfaces was conducted under simple sliding conditions. Findings Under pure sliding conditions, the minimum film thickness presents itself near the marginal bump at lower entrainment velocity. The inlet dimple before the marginal bump is subjected to the operating conditions. Under pure rolling conditions, the shape of the dent is almost unchanged when it is passing through the contact region at lower entrainment velocity. The dent depth hardly depends on the applied load under static conditions. However, larger load enhances the inlet dimple and the elastic deformation of the dent with the marginal bump under pure sliding conditions. Originality/value This work is helpful to understanding the effect of the marginal bump before the single dent on point contact EHL films.

Experimental study of starvation in grease-lubricated finite line contacts

2017 ◽  
Vol 69 (6) ◽  
pp. 963-969 ◽  
Author(s):  
Zhijian Wang ◽  
Xuejin Shen ◽  
Xiaoyang Chen ◽  
Qiang Han ◽  
Lei Shi
Keyword(s):  
Film Thickness ◽  
High Viscosity ◽  
Operating Conditions ◽  
Test Rig ◽  
Oil Viscosity ◽  
Content Type ◽  
Base Oil ◽  
Optical Test ◽  
Line Contacts ◽  
Finite Line

Purpose The purpose of this paper is to study starvation in grease-lubricated finite line contacts and to understand film-forming mechanisms of grease-lubricated finite line contacts. Design/methodology/approach A multiple-contact optical elastohydrodynamic (EHL) test rig is constructed to investigate the influences of lubricant properties on film thickness and lubrication conditions at different working conditions. The film thickness is calculated according to the relative light intensity principle. The degree of starvation is evaluated by the air–oil meniscus distance and the corresponding film thickness. Findings The experimental results show that for greases with high-viscosity base oil, the high-frequency fluctuation of film thickness is observed in low-speed operating conditions. Reducing the viscosity of the base oil and improving running speed can weaken the fluctuation of film thickness. The degree of starvation increases with increasing base oil viscosity, rolling speed and the crown drop. In addition, reducing the replenishment time by reducing the gap between the rollers also can increase the degree of starvation. Originality/value Starvation is often to occur in finite line contacts, such as roller bearings and gears; there are still limited finite line contact EHL test rigs, much less multiple-contact optical test rigs. Therefore, the present work is undertaken to construct the multiple-contact test rig and to evaluate the mechanism of starvation in finite line contacts.

scholarly journals Experimental investigations and analysis on churning losses of splash lubricated spiral bevel gears

2017 ◽  
Vol 18 (4) ◽  
pp. 412 ◽  
Author(s):  
S. Laruelle ◽  
C. Fossier ◽  
C. Changenet ◽  
F. Ville ◽  
S. Koechlin
Keyword(s):  
Experimental Tests ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Spiral Bevel Gear ◽  
Power Losses ◽  
Test Rig ◽  
Specific Test ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Spiral Bevel

Churning losses are a complex phenomenon which generates significant power losses when considering splash lubrication of gear units. However, only few works deal with bevel gears dipped lubrication losses. The objective of this study is to provide a wide variety of experimental tests on churning losses, especially getting interested in geometry of spiral bevel gears influence. A specific test rig was used in order to study a single spiral bevel gear partially immersed in an oil bath. Experiments have been conducted for several operating conditions in terms of speeds, lubricants, temperatures and gear geometries to study their impact on splash lubrication power losses. These experimental results are compared with the predictions from various literature sources. As the results did not agree well with the predictions for all operating conditions, an extended equation derived from previous works is introduced to estimate churning losses of bevel gears.

Thermal insulation effect on EHL of coated cam/tappet contact during start up

2018 ◽  
Vol 70 (6) ◽  
pp. 917-926 ◽  
Author(s):  
Xianghui Meng ◽  
Changya Yu ◽  
Youbai Xie ◽  
Benfu Mei
Keyword(s):  
Thermal Insulation ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Cold Start ◽  
Content Type ◽  
Friction Power ◽  
Warm Start ◽  
Start Up ◽  
Lubrication Performance ◽  
Insulation Effect

Purpose This paper aims to investigate the lubrication performance of cam/tappet contact during start up. Especially, the thermal insulation effects of coating on the lubrication performance during cold start up process and warm start up process are studied. Design/methodology/approach A numerical model for the analysis of thermal elastohydrodynamic lubrication of coated cam/tappet contact is presented. In this model, the Reynolds equation and the energy equations are discretized by the finite difference method and solved jointly. Findings During start up, the contact force at cam nose-to-tappet contact decreases with increasing time, while the absolute entrainment velocity has the upward trend. The minimum film thickness, maximum average temperature and friction power loss increase with increasing time, while the coefficient of friction decreases during start up. Because of the thermal insulation effect, the coating can significantly increase the degree of temperature rise. Compared with the uncoated case, the coated cam/tappet results in a lower friction power loss. Generally, the friction power loss in the cold start up process is much higher than that in the warm start up process. Originality/value By this study, the lubrication performance and the kinematics and the dynamics of the cam/tappet during start up process are investigated. Meanwhile, the thermal insulation effect of coating is also illustrated. The difference of lubrication performance between cold start up process and warm start up process is analyzed. The results and thermal elastohydrodynamic lubrication method presented in this study can be a guidance in the design of the coated cam/tappet.

scholarly journals The Flex-OeCoS—a Novel Optically Accessible Test Rig for the Investigation of Advanced Combustion Processes under Engine-Like Conditions

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1794
Author(s):  
Bruno Schneider ◽  
Christian Schürch ◽  
Konstantinos Boulouchos ◽  
Stefan Herzig ◽  
Marc Hangartner ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Modular Design ◽  
Operating Conditions ◽  
Valve Train ◽  
Experimental Investigations ◽  
Test Rig ◽  
Optical Engine ◽  
Advanced Combustion ◽  
Wide Range ◽  
Combustion Processes

A new test rig has been designed, built and commissioned, and is now jointly pursued to facilitate experimental investigations into advanced combustion processes (i.e., dual fuel, multi-mode) under turbulent conditions at high, engine-like temperature and pressure levels. Based on a standard diesel engine block, it offers much improved optical access to the in-cylinder processes due to its separated and rotated arrangement of the compression volume and combustion chamber, respectively. A fully variable pneumatic valve train and the appropriate preconditioning of the intake air allows it to represent a wide range of engine-like in-cylinder conditions regarding pressures, temperatures and turbulence levels. The modular design of the test rig facilitates easy optimizations of the combustion chamber/cylinder head design regarding different experimental requirements. The name of the new test rig, Flex-OeCoS, denotes its Flexibility regarding Optical engine Combustion diagnostics and/or the development of corresponding Sensing devices and applications. Measurements regarding in-cylinder gas pressures, temperatures and the flow field under typical operating conditions are presented to complete the description and assessment of the new test rig.

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