scholarly journals Calculation of contact pressure and contact zone in slip pairs of marine diesels

2021 ◽  
Vol 27 (1) ◽  
pp. 84-92
Author(s):  
С.В. Сагін ◽  
М.О. Кривий
Keyword(s):  
Numerical Simulations ◽  
Contact Zone ◽  
Cylinder Liner ◽  
Normal Pressure ◽  
Fundamental Solutions ◽  
Theory Of Elasticity ◽  
Hydrodynamic Characteristics ◽  
Maximum Pressure ◽  
Marine Diesel ◽  
Radial Gap

Annotation – The durability of marine diesels significantly depends on the operation of friction pairs, such as: piston rings - cylinder liner; crankshaft - bearing shell, plunger - sleeve, and others. This is primarily due to the constant contact interaction of the elements of the friction pairs at different temperatures and load. Therefore, the research of normal pressure and the definition of contact areas in the friction pairs, the studying of the influence of the quality of lubricants on these characteristics are important tasks for predicting the longevity of marine diesels. The solution of these problems is based on the application of mathematical models of processes (numerical simulations) that occur in friction pairs. This considers two main processes that occur during the operation of the friction pairs: the research of contact and tangential stresses that occur in friction pairs in the framework of elastic or elastic-plastic contact models; study of hydrodynamic processes in a thin layer of oil between the elements of the friction pairs. The combination of these processes allows to sufficiently assess the influence of the elastic-mechanical properties of the sliding vapor elements and the viscosity and hydrodynamic characteristics of the oils on the durability of the marine diesel unit. The first process is researched in this work. In particular, for the analysis of contact stresses and contact zones in friction pairs, the method of numerical modeling is used, which is based on the differential equations of the theory of elasticity. With the help of fundamental solutions (influence functions), the problem is reduced to an integra-differential equation with the Gilbert’s kernel. The solution of which is constructed using the method of orthogonal polynomials as well as easy-to-use approximation formulas. Numerical simulations were performed, as a result, the maximum pressure and contact zone parameters for some combinations of friction pairs materials of marine diesel engines were determined. In particular, the influence of the radial gap on the pressure distribution and the size of the contact zone between the elements of the friction pairs of marine diesels is established.

Experimental Study of Diesel Engine Cycle-to-Cycle Variation—Part II: Correlation of Ignition Delay and Cylinder Pressure Variation

1989 ◽  
Vol 33 (04) ◽  
pp. 310-317
Author(s):  
M. Soonnadum ◽  
R. Latorre ◽  
D. Charnews
Keyword(s):  
Diesel Engine ◽  
Ignition Delay ◽  
Poor Correlation ◽  
Maximum Pressure ◽  
Cylinder Pressure ◽  
Cylinder Test ◽  
Cycle Variation ◽  
Marine Diesel ◽  
Engine Excitation ◽  
Variation Part

Marine diesel engine excitation can occur from the cycle-to-cycle variation in the engine output. The cycle-to-cycle variation in maximum cylinder pressure is often used to represent this variation. Recent tests indicate a poor correlation between the variation in maximum pressure and variation in pressure impulse (PI). This paper summarizes the results of systematic experiments to determine the cycle-to-cycle variation in maximum cylinder pressure, ignition delay (ID), and corresponding ignition pressure in a single-cylinder test diesel engine at various rpm and compression ratios. Comparisons show that there is a high correlation between the cycle-to-cycle variation in ID and PI. Consequently, the variation in the ignition delays should be used instead of the maximum pressure.

scholarly journals Indentation of an S2 Floating Ice Sheet in the Brittle Range

1983 ◽  
Vol 4 ◽  
pp. 180-187 ◽  
Author(s):  
B. Michel ◽  
D. Blanchet
Keyword(s):  
Aspect Ratio ◽  
Research Work ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Theory Of Elasticity ◽  
Maximum Pressure ◽  
Shear Cracks ◽  
Aspect Ratios ◽  
Two Parameters ◽  
The Impact

The problem of a floating ice sheet hitting a structure with a vertical face appears to be a simple one but, in fact, has only been solved for a limited number of cases. Research work on this question usually reports on an indentation coefficient which relates the average pressure on the indenter to the uniaxial crushing strength of the ice. Very few tests have been made in the brittle range of ice failure. In this particular area of study, this paper reports on 27 tests that were conducted in a cold-room water basin where controlled S2floating ice sheets were produced with a surface area of 4 × 4 m, three sides being fully restrained and the other, freely float! no, being submitted to the impact of the moving indenter. All tests were carried out at computed indentation rates varying from 0.017 to 0.34 s-1. In this range this ice would normally be considered to act as a brittle material. The thickness of the ice sheets varied from 1.2 to 9.0 cm and the indenter width from 5 cm to 1 m. Overall, the aspect ratio relating these two parameters could be varied from 0.5 to 83.Results have shown that for aspect ratios <5, there was an important oscillatory effect which caused the formation of pi asti fi ed triangles in front of the indenter, increasing its resistance as it would under ductile conditions. Because of this plastification, an extrusion effect appeared in front of the indenter as the broken ice crystals were blown up and down in front of the fast-moving indenter. The theory of plasticity which gives an indentation coefficient of 2.97 seems to apply in this case. Another mode of failure which occurred with aspect ratios 5 was cleavage in the plane of the ice sheet which also gives a higher indentation coefficient for S2ice, but of the same order of magnitude as previously.For intermediate values of the aspect ratio, between 5 and 20, the theory of elasticity used by Michel (1978) seems to apply well. Shear cracks are first formed on both sides of the square indenter and control the maximum pressure when they propagate inside forming big triangles in front of it.Finally, for aspect ratios ~>20, buckling of the ice occurs, either after or at the same time as the formation of wedges, together with a reduction in the indentation coefficient to a value close to that given by the theory of buckling of a truncated 45° wedge with a hinged edge.

Effects of different surface grooved cylinder liner on the tribological performance for cylinder liner-piston ring components

2019 ◽  
Vol 72 (5) ◽  
pp. 581-588
Author(s):  
Jiazhi Miao ◽  
Yongqing Li ◽  
Xiang Rao ◽  
Libao Zhu ◽  
Zhiwei Guo ◽  
...  
Keyword(s):  
Piston Ring ◽  
Critical Factor ◽  
Cylinder Liner ◽  
Content Type ◽  
Crucial Effect ◽  
Design And Manufacturing ◽  
Marine Engines ◽  
Marine Diesel ◽  
Energy Economy ◽  
Groove Texture

Purpose The emission from marine engines has a crucial effect on energy economy and environment pollution. One of the effective emission reduction schemes is to minimize the friction loss of main friction pairs such as cylinder liner-piston ring (CLPR). Micro-groove textures were designed to accomplish this aim. Design/methodology/approach The authors experimentally investigated the effects of micro-groove textures at different cylinder liner positions. The micro-groove texture was fabricated on samples by chemical etching and cut from the real CLPR pair. Sliding contact tests were conducted by a reciprocation test apparatus. Findings The average friction coefficient of grooves at 30° inclination were reduced up to 58.22% and produced better tribological behavior at most conditions. The operating condition was the critical factor that determined the optimum texture pattern. The surface morphology indicated that textures could produce smoother surfaces and less scratches as compared with the untextured surface. Originality/value Inclined grooves and V-grooves were designed and applied to real CLPR pairs. The knowledge obtained in this study will lead to practical basis for tribological design and manufacturing of CLPR pair in marine diesel engines.

Study on the Hydrodynamic Characteristics for Heave Plate Structure of Truss Spar

2010 ◽  
Author(s):  
Wenjun Shen ◽  
Yougang Tang ◽  
Liqin Liu
Keyword(s):  
Numerical Simulations ◽  
Forced Oscillation ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Hydrodynamic Coefficients ◽  
Plate Structure ◽  
Plate Spacing ◽  
Mesh Method ◽  
Truss Spar ◽  
Heave Plate

The hydrodynamic characteristics of heave plates are studied in this paper. Firstly, different motion amplitudes and plate spacing influencing hydrodynamic coefficients are considered. Secondly, heave plates with different thicknesses are calculated, the case of edges with inclined form for heave plate is also taken into account. Numerical simulations are made for the plate forced oscillation, employing the dynamic mesh method and UDF (User defined functions). The values of Cm and Cd for heave plate are calculated. It is found that, in a certain amplitude range, Cm increases with increasing of amplitudes, Cd decreases with increasing of amplitudes. The values of Cm and Cd increase with increasing of plate spacing. Furthermore with the same effective thickness, the hydrodynamic performance of heave plate with inclined form is improved greatly.

3-D Numerical Simulation and Experiment Study on the Wear of Piston Ring-Cylinder Liner

2010 ◽  
Vol 139-141 ◽  
pp. 1036-1039 ◽  
Author(s):  
Jian Ping Zhang ◽  
Yan Kun Jiang ◽  
Xin Liu ◽  
Zhe Lin Dong
Keyword(s):  
Diesel Engine ◽  
Piston Ring ◽  
Elastohydrodynamic Lubrication ◽  
Cylinder Liner ◽  
Effect Of Temperature ◽  
Wear Loss ◽  
Asperity Contact ◽  
Warm Start ◽  
Deformation Equation ◽  
Marine Diesel

Aiming at a large marine diesel engine, a mathematical model for the 3-D elastohydrodynamic lubrication analysis of piston ring-cylinder liner was presented. The average Reynolds equation and asperity contact approach were combined with the elastic deformation equation. The asymmetry in the circumferential direction, gas blowby and the effect of temperature and pressure on the oil density and viscosity were considered. The 3-D wear simulation of piston ring-cylinder liner was performed when the diesel engine was operated under warm start and cold start conditions, respectively. The 3-D distribution rules show that the first gas ring has the biggest wear loss, and the maximum wear loss of cylinder liner occurs in the vicinity of TDCF. Finally, the results matched well with the wear measurements, and it indicates the present method is effective and can help engineers to improve the tribological performance of the diesel engine.

Friction Resistance between Valve Made of TiAl Alloy and its Guide Made of Phosphor Bronze

2013 ◽  
Vol 404 ◽  
pp. 220-227 ◽  
Author(s):  
Adam Rylski ◽  
Krzysztof Siczek
Keyword(s):  
Contact Zone ◽  
Coefficient Of Friction ◽  
Tial Alloy ◽  
Normal Pressure ◽  
Sound Level ◽  
Friction Resistance ◽  
Pin On Disc ◽  
Material Sample ◽  
Rotating Plate ◽  
Plate Assembly

A lightweight valve is often made of TiAl alloys and its stem can be solid or hollow. Such valves can mate with guides made of cast iron or of phosphor bronze at different conditions in their contact zone valve/quide. The aim of the research was to measure the friction force in the sliding contact between the valve stem made of TiAl alloy and its guide made of phosphor bronze, in the absence of oil. The experiment was conducted at room temperature and in static air under normal pressure. The investigations were conducted with use of the tester, which is presented in this article. The loading of contact zone has varied periodically during series. The displacement and acceleration of valve and the force during its impact into seat insert have been measured during tests. Additionally the sound level has been measured, either. Tests have been provided for different frequency of driving force. Additionally, researches on the tribotester pin-on-disc, presented in the article, have been provided, with the pin made of Ti6Al4V alloy and the disc made of phosphor bronze. The model of research stand has been elaborated for the simulation of dynamics for the material sample rotating plate assembly. The aim of such researches has been to obtain values of coefficient of friction for such tribological pair and to simulate dynamics of the material sample rotating plate assembly, characteristic for used research stand. The obtained courses of coefficient of friction vs. loading, slide velocity, duration of motion of material sample in respect to the rotating plate have been presented in the article. On the base of simulation results the values of damping coefficient have been estimated, which allow to obtain the value for the amplitude of the modeled motion for the material sample in respect to the rotating plate near to the value of the amplitude for the real motion. Such estimation allows forecasting the dynamics of the mentioned assembly for other values of velocity and loading.

scholarly journals Characteristics of modeling hydrodynamic processes of fuel supply in operation of marine diesel using water-fuel emulsion

2020 ◽  
Vol 2020 (2) ◽  
pp. 54-61
Author(s):  
Gennady Bentsianovich Gorelik ◽  
Oleg Nikolaevich Mozolev
Keyword(s):  
High Pressure ◽  
Steady State ◽  
Diesel Fuel ◽  
Alternative Fuels ◽  
Alternative Fuel ◽  
Telegraph Equation ◽  
Maximum Pressure ◽  
Fuel Supply ◽  
Marine Diesel

The article presents the results of mathematical modeling of the fuel supply process of a marine diesel working on diesel fuel and water-fuel emulsion with a water content of 30% as an alternative fuel. There have been found the specific features of fuel supply and the influence of the alternative fuel on the injection characteristics of standard fuel supply equipment during operation in nominal and partial modes. In evaluating the quality of fuel equipment operation on a water-fuel emulsion there were taken into account the following facts: changing of the fuel supply characteristics; changing injection parameters; type of fuel spraying in the initial and final phases of injection and reduction of fuel proportion supplied during the needle landing period; greater stability of successive injection cycles by increasing the active stroke of the plunger by 25-30%; features of injection processes due to thermal explosion effect. The telegraph equation for the unsteady fuel motion in a high pressure pipeline is obtained. The operation parameters of a marine diesel engine 6CHSPN2A 18/22 (DRA-300) are considered in nominal mode according to the screw characteristic for diesel fuel and water-fuel emulsion: plunger stroke of the high-pressure fuel pump; maximum pressure of the steady state in the connecting pipe; average integral pressure of the steady state in the nozzle, which determines the quality of spraying, the speed of landing of the sprayer needle on the saddle; amount of fuel supplied during the needle landing period; cyclic fuel supply; duration of the main injection; stability criterion of fuel supply processes in successive cycles, etc. It has been inferred that water-fuel emulsions can take a separate place in the list of alternative fuels, which will contribute to improving the quality of traditional fuels, productive burnout of hydrocarbon, nitrogen-hydrogen mixture, spirit mixtures, etc. due to the rational introducing additives into fuel, increasing the reliability indicators of cylinder-piston parts, etc.

Sign in / Sign up

Export Citation Format

Share Document