scholarly journals METHODS OF INCREASING CARRYING CAPACITY OF TRANSPORT CONSTRUCTIONS MADE OF METAL CORRUGATED STRUCTURES UNDER OPERATING CONDITIONS

2021 ◽  
pp. 25-48
Author(s):  
Vitalii Kovalchuk ◽  
◽  
Artur Onyshchenko ◽  
Oleg Fedorenko ◽  
Andriy Pentsak ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Operating Conditions

Computational Fluid Dynamics Thermohydrodynamic Analysis of Three-Dimensional Sector-Pad Thrust Bearings With Rectangular Dimples

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
C. I. Papadopoulos ◽  
L. Kaiktsis ◽  
M. Fillon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Carrying Capacity ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Performance Indices ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Texture Design

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of computational fluid dynamics (CFD) simulations, based on the numerical solution of the Navier–Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth, and texture density on the bearing performance indices (load carrying capacity, friction torque, and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

Static and dynamic performance characteristics of powder lubricated symmetrical three-lobed bearing

2020 ◽  
pp. 135065012092632
Author(s):  
Jijo Jose ◽  
Niranjana Behera
Keyword(s):  
Carrying Capacity ◽  
Elevated Temperatures ◽  
Dynamic Performance ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Oil Degradation ◽  
Static And Dynamic Characteristics ◽  
Load Carrying ◽  
The Coefficient Of Friction ◽  
Ellipticity Ratio

Hydrodynamic oil bearings applied at elevated temperatures and extreme operating conditions are subjected to the problem of oil degradation. In order to overcome such conditions, dry powder lubricants are used as lubricants in the hydrodynamic journal bearings. Thus the problem of thermal degradation of oil at high temperatures can be eliminated. In this work, the static and dynamic characteristics of a symmetric three-lobed bearing lubricated with powdered particles have been predicted. Influence of the ellipticity ratio on the performance of the three-lobed bearing has also been investigated. It is observed that an increase in the ellipticity ratio increases the coefficient of friction and stability, but decreases the side leakage and the load carrying capacity of the three-lobed bearing. Also, it was observed that the large-sized powdered particles induce better load carrying capacity and better stability than the small-sized particles.

scholarly journals Indicator for Assessing Availability of Rolling Stock for Public Urban Passenger Transport

2021 ◽  
Vol 18 (6) ◽  
pp. 220-237
Author(s):  
I. V. Spirin ◽  
Yu. M. Grishaeva ◽  
O. Yu. Matantseva
Keyword(s):  
Carrying Capacity ◽  
Operating Conditions ◽  
Rolling Stock ◽  
Basic Unit ◽  
Passenger Transport ◽  
Environment Analysis ◽  
Urban Mass Transit ◽  
Average Operating ◽  
Main Production

The objective of the article is to develop and to substantiate adequacy of the proposed indicator for assessing availability of rolling stock for urban mass transit or urban passenger transport (UPT). As such an indicator, it is recommended to use a calculated indicator: a conventional one-hundred-seat vehicle. The currently used indicators characterising provision of UPT with vehicles, consider only the physical number of the latter. This does not provide an assessment of carrying capacity of UPT, considering the existing operating conditions (real operating speeds on the routes of UPT, the existing level of the coefficient of the fleet being used on the routes as compared to the total number of fleet units, etc.). The proposed indicator of availability of the rolling stock considers not only the natural number of vehicles, but also their passenger capacity, the indicated significant technical and operational indicators of the vehicle fleet. The basis for assessing the carrying capacity of the rolling stock fleet is a conventional one-hundred-seat bus, which performs transportation on routes with an average operating speed. For real buses, this basic unit is adjusted in accordance with real travel speeds and the prevailing values of technical and operational indicators. A similar adjustment is performed for real trolleybuses and tram cars, which makes it possible to level the operational differences in the rolling stock of various types of UPT to compare them in terms of carrying capacity.The methodology used in preparation of the article is based on the integrated use of scientific knowledge in the fields of applied science on operation of transport, statistics (statistical observation and accounting of the work of UPT), a comparative analysis of indicators used in various industries, in particular, in agriculture to assess the level of provision with the main production vehicles (conventional tractor), benchmarking research and development of Russian and foreign authors on the problem of improving operation of UPT.The indicator is intended for use in development and assessment of the level of implementation of programs for development of UPT and the urban environment, analysis of the quality of transport planning and services provided to passengers, comparisons of provision with vehicles in different cities.

scholarly journals ENVIRONMENTAL MANAGEMENT IN JOINT STREAMS REGULATION BY TWO HYDROELECTRIC COMPLEXES

2017 ◽  
Vol 1 ◽  
pp. 23
Author(s):  
M. I. Balzannikov ◽  
A. A. Mikhasek ◽  
V. M. Yurov
Keyword(s):  
Water Supply ◽  
Carrying Capacity ◽  
Water Storage ◽  
Operating Conditions ◽  
Water Runoff ◽  
Complex Structures ◽  
Modes Of Operation ◽  
Control Structures ◽  
Water Power ◽  
Flood Season

Lowland river water power developments are usually built to solve complex tasks on the basis of the requirements of rational use of water resources. First of all, operating conditions of hydroelectric complex structures should provide safety and economic efficiency in their work. Besides, they are aimed to satisfy various demands of water consumers. It is particularly important that behaviour of hydroelectric complex structures should satisfy contemporary requirements of environmental security. The most important task here is to create favourable ecological conditions of life for people who live in settlements located in the zone of influence of two hydroelectric complexes located on different rivers. Here, to achieve environmental targets it is necessary to interlink modes of operation of these water storage control structures. There are two water power developments built in the Republic of Bashkortostan, Russia, in the middle flow of the Belaya River. Both of them have considerable impact on the formation of level mode and different consumers’ water supply. They are Umaguzinskiy and Nugushskiy water power developments. Both hydroelectric complexes and their water reservoirs together satisfy the following generally accepted requirements of water consumers: - they prevent the lowering of the water level in the river Belaya (during low streamflow period) below the minimum values required to ensure proper water supply for industrial enterprises; - they generate electric power and provide industries and cities with electricity. To do that each water-economic complex has its own water reservoir and a set of retaining structures and required culvert installations. In addition, the following environmental requirements are imposed on co-regulation of water runoff: - protection of waterfronts of the towns Meleuz, Salavat, Ishimbay and Sterlitamak from flooding in flood season; -protection of the territories of refineries in flood season (during water rise). Umaguzinskiy water power development has the following water sluices to control water stream: 1) submerged flood-discharge outlet; 2) shore flood spillway; 3) aggregates of powerhouse. General water carrying capacity of hydroelectric complex structures is 3915 м3/c. Nugushskiy hydroelectric complex consists of hydraulic engineering structure power room (1) and left shore spillway (2). Combined water carrying capacity of all hydroelectric complex structures here is 1250 м3/c. The authors investigated operation modes of Nugushskiy and Umaguzinskiy water power developments when linked into one water-economic complex and came to the conclusion that modes of operation of these water storage control structures should be adjusted in accordance with the operational condition of the main pressure installations and of downstream flood-control facilities. In particular, it is necessary to take into account the unfinished state of flood prevention measures in the middle reaches of the river Belaya.

Three-Dimensional Liquid Sloshing Numerical Analysis on a New Designed Tank Container

2019 ◽  
Author(s):  
Wenjun Yue ◽  
Xu Chen
Keyword(s):  
Fluid Flow ◽  
Carrying Capacity ◽  
Impact Force ◽  
Three Dimensional ◽  
Economic Benefits ◽  
Cylindrical Vessel ◽  
Filling Ratio ◽  
Operating Conditions ◽  
New Type ◽  
Maximum Impact Force

Abstract Based on the conventional tank container which has a cylindrical vessel, a new structure of tank container was designed to improve the carrying capacity of the tank. Fluid flow inside the new tank container under different operating conditions (liquid filling ratio K, braking deceleration a, filling medium, no baffle and with baffles) was studied. A volume-of-fluid (VOF) method and a k-epsilon (k-ε) turbulence model were used to simulate the fluid flow. Results showed that all the factors studied in this work had an influence on the tank. The maximum impact force increased with the increasing of a and K. A clear linear positive correlation was found between the maximum impact force and braking deceleration. Besides, the maximum impact force had a relationship with the density of medium. Compared with the conventional tank container, the carrying capacity of the new type tank container increases by 11.8%, which means the new type tank container has better economic benefits.

Paper 1: The Hydrodynamics of Flat Contacts: Friction Studies in the Pin and Disc Machine

1965 ◽  
Vol 180 (11) ◽  
pp. 49-60
Author(s):  
W. G. Robertson ◽  
D. T. Spillman
Keyword(s):  
Carrying Capacity ◽  
Electrical Contact ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Practical Application ◽  
Test Rig ◽  
Mineral Oils ◽  
Wide Range ◽  
Load Carrying ◽  
Flat Steel

The friction of run-in flat steel specimens lubricated with plain mineral oils has been measured in a pin and disc machine over a wide range of operating conditions. The hydrodynamic region was identified with the aid of electrical contact measurements and the corresponding friction data were considered in terms of the various theories which have been proposed to explain hydrodynamic action in nominally flat sliding contacts. It was concluded that the Lewicki inflow, the surface roughness, and the viscosity-density wedge mechanisms could not explain the observed friction; but that it could be explained if the surfaces formed a wedge whose angle was constant over the whole range of operating conditions. It is suggested that the wedge may be formed during the running-in process by mechanical effects such as flexural distortion. Particularly striking is the strength of the hydrodynamics which can occur in such ‘flat’ contacts: in terms of the wedge analysis the contact was operating close to the maximum theoretical load-carrying capacity. The implications with respect to the use of the pin and disc machine as a test rig are discussed and it is suggested that there might be a practical application in the design of ‘self-adjusting‘ slider bearings.

CFD Thermohydrodynamic Analysis of 3-D Sector-Pad Thrust Bearings With Rectangular Dimples

2013 ◽  
Author(s):  
C. I. Papadopoulos ◽  
L. Kaiktsis ◽  
M. Fillon
Keyword(s):  
Carrying Capacity ◽  
Thermal Effects ◽  
Computational Study ◽  
Load Capacity ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Performance Indices ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Texture Design

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of Computational Fluid Dynamics (CFD) simulations, based on the numerical solution of the Navier-Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth and texture density on the bearing performance indices (load carrying capacity, friction torque and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

Thermo-EHD Analysis of Lubrication of Helical Gears

1988 ◽  
Vol 110 (3) ◽  
pp. 330-336 ◽  
Author(s):  
V. Simon
Keyword(s):  
Regression Analysis ◽  
Carrying Capacity ◽  
Power Loss ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Helical Gears ◽  
Oil Film ◽  
Gear Teeth ◽  
Temperature Distributions ◽  
Load Carrying

The full thermal elastohydrodynamic analysis of lubrication of helical gears is presented. A numerical solution of the coupled Reynolds, elasticity, energy, and Laplace’s equations for the oil film shape, pressure and temperature distributions in the oil film, and temperature distribution in gear teeth is obtained. The effects of gear parameters and operating conditions on EHD performance characteristics is discussed. Based on the obtained results, by regression analysis, equations are derived to calculate the EHD load carrying capacity, maximum oil temperature, and power loss.

Tilting-Pad Journal Bearing in Hybrid Operation: A Numerical and Experimental Investigation

2018 ◽  
Author(s):  
Nico Buchhorn ◽  
Sebastian Kukla ◽  
Beate Bender ◽  
Marc Neumann
Keyword(s):  
Hydrostatic Pressure ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Oil Supply ◽  
Hybrid Operation ◽  
Tilting Pad ◽  
Load Carrying ◽  
Tilting Pad Journal Bearing

Large turbine bearings are usually equipped with hydrostatic jacking mechanisms to separate bearing and shaft during transient start-stop procedures. They are turned off once hydrodynamic operation is reached. In some cases, under severe operating conditions, the hydrostatic oil supply is kept running although the rotor already runs in full speed. The supplied amount of jacking oil is very small compared to the regular oil supply. However, experimental data of a large tilting-pad bearing shows that this hybrid operation has a considerable impact on the load carrying capacity in terms of lower pad temperature and larger film thickness. In this paper, a theoretical investigation to analyse the effect of increased load carrying capacity of a large tilting-pad journal bearing in hybrid operation is presented. The increase is driven by three different aspects: 1) hydrostatic pressure component, 2) increase in lubricant viscosity due to the injection of cold oil, 3) decrease of temperature gradients and thus thermal pad deformation. Subject of the approach is a ø500 mm five-pad, rocker-pivot tilting-pad journal bearing in flooded lubrication mode. The experiments are carried out on the Bochum test rig for large turbine bearings. The theoretical analyses are performed with a simulation code solving the Reynolds and energy equations for the oil film and calculating the thermomechanical pad deformations simultaneously. By considering each of the three above aspects separately and in combination, their share of load increase can be assessed individually. Contrary to expectations, the results indicate that the increase is not mostly based on the hydrostatic pressure component. Instead, the advantageously decreased pad deformations make the largest contribution to the increased load carrying capacity while the alteration in viscosity shows the least impact.

Melt Time-Temperature Treatment Affecting the Amorphous Ribbons' Properties of the HTS-42 Solder

2013 ◽  
Vol 871 ◽  
pp. 147-151 ◽  
Author(s):  
Vladimir Tsepelev ◽  
Viktor Konashkov ◽  
Vladimir Vyukhin ◽  
Arkadi Povodator ◽  
Ann Latipova
Keyword(s):  
High Temperature ◽  
Thermal Treatment ◽  
Carrying Capacity ◽  
Precipitation Hardening ◽  
Temperature Treatment ◽  
Operating Conditions ◽  
Resource Saving ◽  
Optimal Operating ◽  
Amorphous Ribbons ◽  
High Temperature Solder

The HTS-42 (High Temperature Solder) properties in the liquid state have been studied. The optimal operating conditions for the solder melt time-temperature treatment, used for producing amorphous ribbons having the specified service properties, are recommended based on the analysis of the anomalies properties and temperature polytherms shape. The subsequent thermal treatment of soldered joints is not shown appropriate for soldering homogeneous melts not hardened by age (precipitation) hardening. The strength of such products can be improved by increasing the contact joint area. The HTS-42 solder amorphous ribbons enable, as compared to the powder semi-finished product, reducing its consumption by 2-3 times, improving the carrying capacity of soldered constructions by 20-40 %, which makes the soldering practice resource saving and significantly improves the product reliability.

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