Conrod Bearings With an Optimized Narrow Circumferential Oil Groove: Simulated Durability Improvement for Heavy-Duty Applications

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Konstantinos Kalogiannis ◽  
David R. Merritt ◽  
Omar Mian ◽  
Hugh Gibson
Keyword(s):  
Negative Impact ◽  
Elastohydrodynamic Lubrication ◽  
Design Feature ◽  
Operating Conditions ◽  
Temperature Dependent ◽  
Operating Life ◽  
Oil Film ◽  
Significant Temperature ◽  
Bearing Design ◽  
Engine Crankshaft

Under normal operating conditions, engine crankshaft bearings experience variations in oil film temperature due to shearing of the oil film. This can have a negative impact on the bearing operating life since the viscosity of the lubricant is temperature dependent. In the current study, a thermo-elastohydrodynamic lubrication (TEHL) analysis has been conducted using an in-house specialized simulation package called (software for analysis of bearings in reciprocating engines) SABRE-TEHL. This advanced simulation tool has been used to optimize a new bearing design feature leading to a significant temperature reduction, which in turn increases the robustness of the system.

Conrod Bearings With an Optimized Narrow Circumferential Oil Groove: Simulated Durability Improvement for Heavy-Duty Applications

2014 ◽  
Author(s):  
Konstantinos Kalogiannis ◽  
David Merritt ◽  
Omar Mian ◽  
Hugh Gibson
Keyword(s):  
Negative Impact ◽  
Elastohydrodynamic Lubrication ◽  
Design Feature ◽  
Operating Conditions ◽  
Temperature Dependent ◽  
Operating Life ◽  
Oil Film ◽  
Significant Temperature ◽  
Bearing Design ◽  
Engine Crankshaft

Under normal operating conditions, engine crankshaft bearings experience variations in oil film temperature due to shearing of the oil film. This can have a negative impact on the bearing operating life since the viscosity of the lubricant is temperature dependent. In the current study, a thermo-elastohydrodynamic lubrication (TEHL) analysis has been conducted using an in-house specialized simulation package called SABRE-TEHL. This advanced simulation tool has been used to optimize a new bearing design feature leading to a significant temperature reduction, which in turns increases the robustness of the system.

Thermal Elastohydrodynamic Lubrication of Rider Rings

1984 ◽  
Vol 106 (4) ◽  
pp. 492-498 ◽  
Author(s):  
Vilmos Simon
Keyword(s):  
Film Thickness ◽  
Numerical Solution ◽  
Temperature Variation ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Oil Film ◽  
The Real ◽  
Ring Geometry

The full thermal elastohydrodynamic analysis of the lubrication of rider rings is presented. A numerical solution of the coupled Reynolds, elasticity, energy, and Laplace’s equations for the oil film thickness, pressure, and temperature and rider rings temperatures is obtained. The temperature variation across the oil film is included. The real rider ring geometry is treated. The effect of the operating conditions on the performance characteristics is discussed.

Wildhaber-Novikov Circular Arc Gears: Elastohydrodynamics

1993 ◽  
Vol 115 (3) ◽  
pp. 487-492 ◽  
Author(s):  
H. P. Evans ◽  
R. W. Snidle
Keyword(s):  
Film Thickness ◽  
Elastic Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Major Axis ◽  
Operating Conditions ◽  
Circular Arc ◽  
Rolling Velocity ◽  
Oil Film ◽  
Practical Design ◽  
Thinning Effect

The paper describes an elastohydrodynamic lubrication (EHL) analysis of heavily loaded contacts between the teeth of Wildhaber-Novikov (W-N) circular arc gears. The contacts occurring in gears of this type are elliptical in shape with lubricant entrainment in the direction of the major axis of the contact. The results shown refer to a particular practical design and cover a range of operating conditions encountered in practice. Because of the high rolling velocity in W-N gears a relatively thick oil film is predicted over most of the contact. Severe thinning of the film occurs at the sides of the contact, however. Results of the full EHL analysis are compared with predictions using a published film thickness formula based upon analysis of moderately loaded elliptical contacts. It is suggested that the side-thinning effect is dependent upon the relative elastic deformation occurring in the contact.

Elastohydrodynamic Lubrication of Hypoid Gears

1981 ◽  
Vol 103 (1) ◽  
pp. 195-203 ◽  
Author(s):  
V. Simon
Keyword(s):  
Film Thickness ◽  
Numerical Solution ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Temperature Variations ◽  
Hypoid Gears ◽  
Oil Film ◽  
Gear Teeth ◽  
Energy Equations

The full thermal elastohydrodynamic analysis of the lubrication of hypoid gears is presented. A numerical solution of the coupled Reynolds, elasticity and energy equations for the pressure, temperature and film thickness is obtained. The temperature variations across the oil film and in the pinion and gear teeth are included. The real tooth geometry of the modified hypoid gears is treated. The effect of the operating conditions on the performance characteristics is discussed.

scholarly journals Steel quality of rolling contact bearings produced by different manufacturers, used for mining equipment instrumentation

2021 ◽  
Vol 315 ◽  
pp. 03019
Author(s):  
Aleksandr Korotkov ◽  
Lidiya Korotkova ◽  
Stefan Voeth ◽  
Roman Solentsov
Keyword(s):  
Quality Control ◽  
Negative Impact ◽  
Bearing Steel ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Mining Equipment ◽  
Operating Life ◽  
Premature Failure ◽  
Steel Quality

Severe operating conditions of mining equipment have a negative impact on the operating life of the rolling contact bearings used in such equipment. The main reasons for the premature failure of rolling contact bearings include, first of all, poor quality of the bearing steel as delivered and the defects of their subsequent heat treatment. The abovementioned reasons result in splitting of bearings, metal shelling and appearance of potholes on their tracks, as well as intense abrasive wear. Nevertheless, despite the importance of this issue, the quality of bearing steel, either as delivered or in finished bearings, is usually not under control.To solve this problem, the quality of bearing steel was studied, exemplified by the bearings of the Russian, Swedish (SKF) and Japanese (NSK) manufacturers, i.e., main suppliers of rolling contact bearings for mining equipment in Russia. The problem of bearing steel quality control was solved by developing a quality control methodology that took into account the state of the metal after metallurgical treatment and at the stage of bearing production. Based on this methodology, the main types of bearing steel defects affecting the mechanism of bearing failure are identified.It is found that the bearing steel quality of domestic manufacturers is highly competitive with foreign counterparts. A method of nondestructive control is also proposed for detecting possible microstructure defects in bearings, either as delivered or while in operation.

The Influence of Surface Roughness on Elastohydrodynamic Journal Bearing With Non-Newtonian Lubricants

2005 ◽  
Author(s):  
Mongkol Mongkolwongrojn ◽  
Chatchai Aiumpornsin ◽  
Somnuk Yawong
Keyword(s):  
Surface Roughness ◽  
Elastic Deformation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Elastohydrodynamic Lubrication ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Static Characteristics ◽  
Heavy Load ◽  
Oil Film

In this paper, the effect of surface roughness and elastic deformation of bearing liner on the static characteristics of journal bearings are presented. A power law model is developed for the elastohydrodynamic lubrication regime. The modified Reynolds equations with elasticity equation were formulated for the elastohydrodynamic journal bearings under heavy load conditions. Multigrid and multilevel technique with Newton’s method were used to calculated the elastohydrodynamic bearing to obtain the oil film pressure profile, oil film thickness profile, load capacity, attitude angle and friction coefficient at various surface roughness parameters. The static characteristics of the rough elastohydrodynamic journal bearing were compared with that of the rough hydrodynamic journal bearings. The results show that the surface roughness and elastic deformation significantly affect the static characteristics of journal bearings under severe operating conditions.

Lubrication state identification of the line contact tribo-pair under a pure rolling condition with ultrasonic method

2021 ◽  
pp. 135065012110337
Author(s):  
Zhihe Duan ◽  
Tonghai Wu
Keyword(s):  
Theoretical Analysis ◽  
Film Thickness ◽  
Ultrasonic Method ◽  
Elastohydrodynamic Lubrication ◽  
Theoretical Models ◽  
Lubrication Theory ◽  
Operating Conditions ◽  
Line Contact ◽  
Oil Film ◽  
Pure Rolling

A line contact tribo-pair is a key mechanism unit in rolling bearings, which is often characterized by ultra-high contact pressure and ultra-thin oil film. Elastohydrodynamic lubrication is often adopted to characterize the lubrication state of such a tribo-pair. As a primary parameter for elastohydrodynamic lubrication, the oil film thickness is often evaluated with simplified theoretical models or complicated measurements. So far, a comprehensive verification of the lubrication states in a real line-contact tribo-pair, however, is rarely reported. Focusing on the roller/ring tribo-pair of a wet-lubricated rolling bearing under pure rolling conditions, this study investigates the lubrication states by integrating multiple theories. Five regions including isoviscous hydrodynamic, piezoviscous hydrodynamic, elastohydrodynamic lubrication, mixture lubrication, and boundary lubrication regions can be identified using the framework. Then, validation experiments are carried out on a line contact tribo-pair test rig under the same operating conditions applied in the theoretical analysis. The oil film thickness is measured by the ultrasonic method. The analysis results demonstrate that only two regions, the elastohydrodynamic lubrication and mixture lubrication regions, can be identified using the experimental data. The identified elastohydrodynamic lubrication and mixture lubrication regions are consistent with theoretical analysis; and the Blok equation and elastohydrodynamic lubrication theory are suggested to calculate the oil film thickness in the elastohydrodynamic lubrication and mixture lubrication regions, respectively. Moreover, the oil film thickness calculated by the Dowson equation is larger than that based on the elastohydrodynamic lubrication theory due to a different viscous pressure equation.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

scholarly journals The importance of species interactions in eco-evolutionary community dynamics under climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anna Åkesson ◽  
Alva Curtsdotter ◽  
Anna Eklöf ◽  
Bo Ebenman ◽  
Jon Norberg ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Interactions ◽  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Negative Impact ◽  
Trophic Levels ◽  
Temperature Dependent ◽  
Modeling Framework ◽  
Impact Of Climate Change ◽  
The Impact

AbstractEco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species’ interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes.

Flow Coefficient Evaluation of Poppet Valves Used in Reciprocating Compressors for LDPE

2008 ◽  
Author(s):  
Enzo Giacomelli ◽  
Massimo Schiavone ◽  
Fabio Manfrone ◽  
Andrea Raggi
Keyword(s):  
Pressure Drop ◽  
Time Pressure ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Operating Life ◽  
High Fatigue ◽  
Strongly Connected ◽  
And Performance ◽  
Poppet Valves

Poppet valves have been used for a long time for very high pressure reciprocating compressors, as for example in the case of Low Density Polyethylene. These applications are very critical because the final pressure can reach 350 MPa and the evaluation of the performance of the machines is strongly connected to the proper operation and performance of the valve itself. The arrangement of cylinders requires generally a certain compactness of valve to withstand high fatigue stresses, but at the same time pressure drop and operating life are very important. In recent years the reliability of the machines has been improving over and over and the customers’ needs are very stringent. Therefore the use of poppet valves has been extended to other cases. In general the mentioned applications are heavy duty services and the simulation of the valves require some coefficients to be used in the differential equations, able to describe the movement of plate/disk or poppet and the flow and related pressure drop through the valves. Such coefficients are often determined in an experimental way in order to have a simulation closer to the real operating conditions. For the flow coefficients it is also possible today to use theoretical programs capable of determining the needed values in a quick and economical way. Some investigations have been carried out to determine the values for certain geometries of poppet valves. The results of the theory have been compared with some experimental tests. The good agreement between the various methods indicates the most suitable procedure to be applied in order to have reliable data. The advantage is evident as the time necessary for the theoretical procedure is faster and less expensive. This is of significant importance at the time of the design and also in case of a need to provide timely technical support for the operating behavior of the valves. Particularly for LDPE, the optimization of all the parameters is strongly necessary. The fatigue stresses of cylinder heads and valve bodies have to match in fact with gas passage turbulence and pressure drop, added to the mechanical behavior of the poppet valve components.

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