HYDRODYNAMIC CALCULATION OF A WEDGE-SHAPED SYSTEM «SLIDER – GUIDE» OPERATING ON A COMPRESSIBLE LUBRICANT IN THE PRESENCE OF MELT ON THE SURFACE OF THE GUIDE

2021 ◽  
Vol 2 ◽  
pp. 109-117
Author(s):  
K.S. AKHVERDIEV ◽  
E.A. BOLGOVA ◽  
E.O. LAGUNOVA ◽  
S.V. KUMANIN
Keyword(s):  
Equations Of State ◽  
Hydrodynamic Lubrication ◽  
Extreme Case ◽  
Calculation Model ◽  
Metal Coating ◽  
Scientific Article ◽  
Hydrodynamic Mode ◽  
Support Ring ◽  
Wide Range ◽  
Mathematical Calculation

Recently, various methods have been used to ensure the hydrodynamic mode of lubrication, one of the methods is devoted to this scientific article. In the article, on the basis of the equation of motion of a compressible, truly viscous liquid for a "thin layer", the equations of state, the continuity equation, as well as the equations describing the profile of the molten contour of the surface of the support ring, an asymptotic and self-similar solution is found for the zero (without taking into account the melt) and the first (taking into account the melt) approximation, for determining the velocity field and pressure in the lubricating layer. For the profile of the molten contour and the pressure, the solution is found by the method of sequential approximation, for the extreme and non-extreme case. As a result, a refined mathematical calculation model of a wedge-shaped sliding support with a low-melting metal coating on the movable contact surface is developed, which compensates for the emergency lack of lubricant and provides a stable hydrodynamic lubrication mode, which allows determining the bearing capacity and friction force. As a result of numerical analysis, the obtained refined mathematical calculation model of a wedge-shaped sliding support with a low-melting metal coating on the surface of the support ring, taking into account the compressibility of the liquid lubricant and the coating melt, and experimental research, the effectiveness of the obtained complex of refined models that allow performing both pre-design evaluation and design engineering calculations, in a wide range of operational load-speed modes, as well as the mechanism and stages of transition to lubrication with metal sprays is established, providing an increase in the level of the main tribotechnical parameters and the resource of tribosystems.

scholarly journals Hydrodynamic calculation of wedge-shaped system «slider-guide» operating on compressible lubricant in presence of melt on surface of guide

2021 ◽  
pp. 10-14
Author(s):  
K. S. Akhverdiev ◽  
◽  
E. A. Bolgovа ◽  
E. O. Lagunova ◽  
S. V. Kumanin ◽  
...  
Keyword(s):  
Hydrodynamic Lubrication ◽  
Mechanical Energy ◽  
Extreme Case ◽  
Calculation Model ◽  
Hydrodynamic Calculation ◽  
Self Similar Solution ◽  
Lubrication Mode ◽  
Mechanical Energy Dissipation ◽  
Self Similar ◽  
Compressible Lubricant

In the article on the basis of the equation of motion of the compressible lubricant for the «thin layer», continuity, state, and the equation describing the profile of the molten contour taking into account the formula of mechanical energy dissipation the asymptotic and self-similar solution is found for the extreme (when the speed tends to infinity) and non-extreme case. As a result of solving the problem, a refined mathematical calculation model of a wedgeshaped sliding support with a low-melting metal coating on a movable contact surface is obtained, which compensates for an emergency lack of lubricant and provides a stable hydrodynamic lubrication mode

Wide-range equations of state for organic liquids

2007 ◽  
Vol 5 ◽  
pp. 113-120 ◽  
Author(s):  
R.Kh. Bolotnova
Keyword(s):  
High Pressures ◽  
Equations Of State ◽  
Organic Liquids ◽  
Liquid Phases ◽  
Wide Range ◽  
High Pressures And Temperatures

The method of construction the wide-range equations of state for organic liquids, describing the gas and liquid phases including dissociation and ionization which occurs during an intense collapse of steam bubbles and accompanied by ultra-high pressures and temperatures, is proposed.

Legal aspects of the brand protection in Ukraine and world

2020 ◽  
pp. 133-143
Author(s):  
Ivanna Babetska
Keyword(s):  
Public Relations ◽  
Practical Importance ◽  
Legal Protection ◽  
Legal Regulation ◽  
Legal Aspects ◽  
Scientific Article ◽  
Protection Mechanism ◽  
Brand Protection ◽  
Wide Range ◽  
International Regulations

Purpose. The purpose of the scientific article is to establish the ratio of the meanings of the concepts "trademark", "brand" and "well-known" trademark and then to characterize their common and distinctive features. Indicate the gaps in current legislation and the need to refine certain rules in this aspect to determine the aspects of protection and protection of the brand. Methodology. The methodology includes a comprehensive analysis and generalization of the available scientific and theoretical material and the formulation of appropriate conclusions and recommendations. During the research, the following methods of scientific knowledge were used: terminological, dialectical, logical-semantic, logical-normative, system-structural. Results: in the course of the conducted study, the main and optional components of the brand are determined, which make it possible to determine the features of its legal protection. It has been proved that despite a fairly wide range of domestic and international regulations, there are certain shortcomings of the brand protection mechanism. Originality. The study found that a trademark differs from a brand in that a trademark is a designation that is only the basis of the brand, as for the trademark are not essential such properties of the designation as a certain level of information among consumers and quality as a basis. gaining a reputation; the concept of "brand" is an evaluative, conditional concept, and therefore its consolidation at the regulatory level is impractical. It is sufficient to establish the factors on the basis of which the trademark can be considered "well known". A "well-known" trademark is a designation that is familiar to a wide range of consumers through its use to designate certain goods. Practical importance. The results of the study can be used in law-making activities for the purpose of legal regulation of public relations in the sphere of legal protection of the brand.

Bearing profile of sliding tribological systems

2021 ◽  
pp. 53-56
Author(s):  
Keyword(s):  
Hydrodynamic Lubrication ◽  
Surface Profile ◽  
Experimental Methods ◽  
Hydrodynamic Characteristics ◽  
Bearing Surface ◽  
Tabular Data ◽  
Sliding Bearing ◽  
Friction Process ◽  
Operational Characteristics ◽  
Wide Range

The main contours of the bearing surfaces of friction pairs with hydrodynamic lubrication are considered. Analysis of tabular data and graphs obtained by experimental methods made it possible to establish additional parameters of influence on the hydrodynamic characteristics of the friction process and the operational characteristics of tribological systems, in a wide range of load-speed modes. Keywords: sliding bearing, hydrodynamics, bushing, bearing surface, profile, circle, ellipse, wavy contour, wear. [email protected]

Vibration-based fault diagnosis of helical gear pair with tooth surface wear considering time-varying friction coefficient under mixed EHL condition

2021 ◽  
pp. 1-16
Author(s):  
Siyu Wang ◽  
Rupeng Zhu
Keyword(s):  
Dynamic Response ◽  
Hydrodynamic Lubrication ◽  
Helical Gear ◽  
Calculation Model ◽  
Tooth Surface ◽  
Time Varying ◽  
Gear Pair ◽  
Surface Wear ◽  
Mesh Stiffness ◽  
Helical Gear Pair

Abstract Based on “slice method”, the improved time-varying mesh stiffness (TVMS) calculation model of helical gear pair with tooth surface wear is proposed, in which the effect of friction force that obtained under mixed elasto-hydrodynamic lubrication (EHL) is considered in the model. Based on the improved TVMS calculation model, the dynamic model of helical gear system is established, then the influence of tooth wear parameters on the dynamic response is studied. The results illustrate that the varying reduction extents of mesh stiffness along tooth profile under tooth surface wear, in addition, the dynamic response in time-domain and frequency-domain present significant decline in amplitude under deteriorating wear condition.

scholarly journals Optimization Aspects of an Ejector Type Hypersonic Thrust Nozzle

1992 ◽  
Author(s):  
G. Trittler ◽  
E. Eckert ◽  
M. Göing
Keyword(s):  
High Performance ◽  
Exhaust System ◽  
Vital Role ◽  
Calculation Model ◽  
Nozzle Geometry ◽  
Design Parameters ◽  
Axial Thrust ◽  
Thrust Coefficient ◽  
Wide Range ◽  
Low Performance

Hypersonic aircraft projects are highly dependant on efficient propulsion systems. High performance and integration within the airframe play a vital role in the overall concept. Particular attention must be paid to the exhaust system that is submitted to a wide range of operational requirements. An optimization of the nozzle geometry for high flight Mach numbers will lead to a low performance at the transonic flight regime. The additional use of secondary ejector air flow at transonic speeds is one option to improve the thrust behaviour of the nozzle. In the presented paper performance data of single expansion ramp ejector type nozzles are predicted using a calculation model based on a method-of-characteristics algorithm. For optimization purposes the effects of various design parameters on axial thrust coefficient and thrust vector angle are discussed. The geometric parameters investigated are the length of the lower nozzle wall and its deflection angle as well as the ejector slot location and its cross-section.

Detailed analysis of piston secondary motion and tribological performance

2019 ◽  
Vol 21 (9) ◽  
pp. 1647-1661 ◽  
Author(s):  
Cristiana Delprete ◽  
Abbas Razavykia ◽  
Paolo Baldissera
Keyword(s):  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Tribological Performance ◽  
System Of Nonlinear Equations ◽  
Piston Skirt ◽  
Wide Range ◽  
Secondary Motion ◽  
Piston Ring Pack ◽  
Ring Pack

This article presents a detailed analytical model to evaluate piston skirt tribology under hydrodynamic lubrication. The contribution of the piston ring pack lubrication has been taken into account to study piston secondary motion and tribological performance. A system of nonlinear equations comprising Reynolds equation and force equilibrium is solved to calculate piston ring pack friction force and its moment about wrist pin axis. Instantaneous minimum oil film thickness at piston ring/liner interface has been estimated considering different boundary conditions: full Sommerfeld, oil separation, and Reynolds cavitation and reformation. The ring pack model has capability to be used for a wide range of ring face profiles under boundary and hydrodynamic lubrication. Piston secondary motion is evaluated using lubrication theory and equilibrium of forces and moments, to examine the effect of wrist pin location, piston skirt/liner clearance, and oil rheology. Numerical method and finite difference scheme have been used to define piston eccentricity and hydrodynamic pressure acting over the skirt.

Lubrication at point contacts

1961 ◽  
Vol 261 (1307) ◽  
pp. 532-550 ◽  
Keyword(s):  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Single Point ◽  
Applied Pressure ◽  
Hydrodynamic Theory ◽  
Radius Of Curvature ◽  
Point Contacts ◽  
Wide Range ◽  
Electrical Capacity ◽  
Classical Hydrodynamic

Measurements have been made of the friction, electrical resistance, and electrical capacity between rotating steel cylinders with their axes mutually at right angles. The lubricant was a plain hydrocarbon mineral oil. Nominally the surfaces come together at a single point and the apparatus is designed to ensure that this condition is maintained even if the cylinders wear. It is shown that hydrodynamic lubrication exists over a wide range of conditions. At loads of a few kilograms it persists even when the speed falls below 1 cm/s and at higher speeds (~ 100 cm/s) it is maintained even when the load becomes large enough to cause bulk plastic flow of hardened steel. Hitherto it has been considered that only boundary lubrication could occur under these extreme conditions. At very light loads classical hydrodynamic theory applies but as the load is increased a departure from classical theory occurs because the viscosity of the oil increases under the applied pressure. At heavier loads the pressures become large enough to cause appreciable elastic deformation of the surfaces and a state of elasto-hydrodynamic lubrication is achieved. Under elasto-hydrodynamic conditions the film thickness can be deduced from the measure­ments of electrical capacity. A simplified theory of elasto-hydrodynamic lubrication at point contacts is developed, and the measured values of film thickness are in fairly good agreement with those derived from the theory. However, the variations of film thick­ness with viscosity, speed and radius of curvature forecast by the theory differ significantly from those obtained experimentally. The values of the film thickness range from 2 x 10 -6 cm to more than 1 x 10 -4 cm. The results, over the whole range, conform to a regular pattern and there is no evidence of any disturbing influence of the surface molecular fields, even with the thinnest films.

scholarly journals A general existence result for isothermal two-phase flows with phase transition

2019 ◽  
Vol 16 (04) ◽  
pp. 595-637
Author(s):  
Maren Hantke ◽  
Ferdinand Thein
Keyword(s):  
Phase Transition ◽  
Euler Equations ◽  
Equations Of State ◽  
Linear Equations ◽  
Two Phase Flows ◽  
Kinetic Relation ◽  
Two Phase ◽  
Uniqueness Results ◽  
Wide Range ◽  
Isothermal Euler Equations

Liquid–vapor flows with phase transitions have a wide range of applications. Isothermal two-phase flows described by a single set of isothermal Euler equations, where the mass transfer is modeled by a kinetic relation, have been investigated analytically in [M. Hantke, W. Dreyer and G. Warnecke, Exact solutions to the Riemann problem for compressible isothermal Euler equations for two-phase flows with and without phase transition, Quart. Appl. Math. 71(3) (2013) 509–540]. This work was restricted to liquid water and its vapor modeled by linear equations of state. The focus of this work lies on the generalization of the primary results to arbitrary substances, arbitrary equations of state and thus a more general kinetic relation. We prove existence and uniqueness results for Riemann problems. In particular, nucleation and cavitation are discussed.

Performance of Graphite and Boron-Nitride-Silicone Based Lubricants and Associated Lubrication Mechanisms in Warm Forging of Aluminum

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Gracious Ngaile ◽  
Frank Botz
Keyword(s):  
Boron Nitride ◽  
Thermal Degradation ◽  
Thermal Oxidation ◽  
Silicone Oil ◽  
Hydrodynamic Lubrication ◽  
Polydimethyl Siloxane ◽  
Wide Range ◽  
Significant Difference ◽  
Warm Forging ◽  
Lubrication Mechanisms

Although water/oil-graphite emulsions are widely used in warm forging processes, they carry environmental concerns. In an attempt to replace graphite-based lubricants in warm forging of aluminum alloys, two variants of boron-nitride-silicone lubricants were formulated. The two variants were made by dispersing boron nitride powder in polydimethyl siloxane oil at concentrations of 1% and 8%. The formulated lubricants were initially tested for their thermal degradation characteristics using a thermogravimetric analyzer and compared to the thermal degradation behavior of graphite and silicone oil lubricants. Ring compression tests were then carried out at 260°C and 370°C. Boron-nitride-silicone lubricant variants did not show significant difference in performance as die temperature was increased from 260°Cto370°C. This is in contrast to graphite, which performed much better at 260°C than at 370°C, due to thermal oxidation. On the other hand, silicone oil exhibited the worst performance at 260°C and the best performance at 370°C. In both boron nitride lubricant variants, the polydimethyl siloxane facilitated hydrostatic/hydrodynamic lubrication at 260°C, with boron nitride acting as a barrier film that reduced friction. However, the lubrication mechanisms changed at 370°C, where the depolymerization of polydimethyl siloxane led to formation of silica due to thermal oxidation. Silica, together with boron nitride, acted as a film barrier with low shear strength. The dual lubrication mechanisms make boron-nitride-silicone lubricants suitable for a wide range of aluminum forging temperatures.

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