Internal Combustion Engine Piston Research Articles

Three-dimensional CFD-solid mechanics analysis of the hydrogen internal combustion engine piston subjected to thermomechanical loads

Fueling internal combustion engines with hydrogen is one of the most recommended alternative fuels today in order to combat the energy crisis, pollution problems, and climate change. Despite all the advantages of hydrogen fuel, it produces a higher combustion temperature than gasoline. In an internal combustion engine, the piston is among the numerous complex and highly loaded components. Piston surfaces are directly affected by combustion flames, making them critical components of engines. To examine the stress distribution and specify the critical fracture zones in the piston for hydrogen fuel engines, a three-dimensional CFD-solid-mechanics model of the internal combustion engine piston subjected to real thermomechanical loads was analyzed numerically to investigate the distribution of the temperature on the piston body, the interrelated thermomechanical deformations map, and the pattern of the stresses when fueling the engine with hydrogen fuel. With the aid of multiphysics COMSOL software, the CFD-solid-mechanics equations were solved with high accuracy. Despite the increase in pressure on the piston and its temperature when the engine is running on hydrogen fuel, the results show that the hydrogen fuel engine piston can withstand, safely, the thermomechanical loads. In comparison to gasoline fuel, hydrogen fuel caused a deformation of 0.34 mm, an increase of 17%. This deformation is within safe limits, with an average clearance of 0.867 mm between the cylinder liner and piston.

A review on preparation process and tribological performance of coatings for internal combustion engine piston ring

Reducing the energy consumption and exhaust emission, and improving the combustion efficiency of internal combustion engine are important for solving the problems of climate change and environmental pollution. The piston ring-liner system is one of the most serious friction pairs in internal combustion engine, accounting for 26% of the total friction loss. Depositing strengthened coatings on the surface of piston rings is an effective method to reduce the friction coefficient and wear rate. This paper reviews the research progress of several representative technologies for preparing coatings, such as electroplating, physical vapor deposition (PVD), thermal spraying and chemical vapor deposition (CVD), and so on. Various coatings, such as Cr-Al2O3 coating prepared by representative electroplating process, CrN and DLC coatings prepared by physical vapor deposition, and Mo-based and C-based coatings prepared by thermal spraying process, are briefly discussed. Furthermore, the positive and negative aspects of commonly used piston ring coatings are compared, and their development trends are summarized.

Estimation of the degree of internal recirculation in Internal Combustion Engines

The concepts of residual gas and admission (or volumetric efficiency) coefficients are used exclusively by specialists in the field of piston Internal Combustion Engines. However, it is preferable to apply the concepts of volume fractions of components of the working mixture consisting of air, fuel, residual, and recirculating gases, for the evaluation of filling. This simplifies and makes it more easy-to-grasp the influence of individual factors on the results of gas exchange processes. The proposed approach makes it possible to take into account the impact on the engine indicators of the molecular weight of the fuel used and the degree of external recirculation, as well as to reduce the number of independent variables. At the same time, the displacement coefficient A proposed by the author characterizes a decrease in filling when an engine with external mixing is switched to a gaseous fuel with a lower molecular weight. A change in the valve timing made it possible to produce an effect on the composition of the working mixture and, thereby, the environmental characteristics of the engine. In the case of external recirculation, it becomes necessary to estimate the summary fraction of neutral combustion products in the working mixture, on which all engine operation depended. This "overall degree of recirculation" can also be determined using the proposed approach.

Coatings protecting against aviation piston engine seizure

The article presents the basics of manufacturing porous (16%) composite coatings based on phenolic resin reinforced with glassy carbon particles (30 wt%). These coatings, when applied to a steel push rod surface, prepared by sandblasting, of the timing system of an aircraft piston internal combustion engine, prevent seizure of the contact in conditions of lubrication failure up to 10 h (μ≈0.1 by p = 8 MPa, v = 0.5 m/s), extending the last stage of flight time of the aircraft. The reference coating undergone seizure, μ> 1 after 5 h. The conditions and results of laboratory tests on a pin-on-disc tribological tester and tests on an engine test bench are described. The dependencies of the coefficient of friction and wear of the push rod on the glassy carbon content, thinner viscosity and sandblasting pressure, described by the equations of the second degree, allowed the optimal conditions to be determined to the produce coatings. The test results of the developed composite porous coatings were compared with the results of non-porous commercial coatings. The wear of developed coating compared to reference one and matrix coatings was respectively ΔmCC = −1.63 mg (mass increase), ΔmRC = 1.3 mg and ΔmMC = 5.56 mg.

The Theory of the Surface Wettability Angle in the Formation of an Oil Film in Internal Combustion Piston Engines

The Theory of the Surface Wettability Angle in the Formation of an Oil Film in Internal Combustion Piston Engines

Analysis of the Welding Process of Steel Pistons of Internal Combustion Engines

The aim of the article is to analyze the friction welding process of steel pistons, due to the small amount of scientific literature on this subject. First, it is necessary to present the design fea-tures of steel pistons and their advantages and disadvantages. Then analyze the types of friction weld-ing processes used in the production of pistons of internal combustion engines with the analysis of their differences. Present two basic methods of welding in the production of steel pistons, i.e. friction butt welding and low pressure friction welding. Finally, a proper analysis of the friction welding pro-cesses of steel pistons of internal combustion engines can be presented. At the end, the conclusions of the analysis are presented and proposals for improving the process are made.

Method and a Device for Testing the Friction Force in Precision Pairs of Injection Apparatus of the Self-Ignition Engines

This article reviews the state of the knowledge and technology in the field of friction-loss measurements in internal combustion piston engines. The dependencies that describe the loss of energy in combustion engines and injection apparatus are presented. Currently, very little can be found in the literature on the study of frictional forces in injection apparatus, but mainly in the piston–cylinder group, so this work significantly fills that gap. The aim of this article is to construct a device and to develop a method for assessing the technical state of injector nozzles to minimize friction losses in internal combustion engines at the stages of evaluation, design, production and operation. This article presents a stand for determining the maximum friction forces due to gravity loading by water-jet control. This article also presents test results on the maximum friction force between a needle and a body of injector nozzles in piston combustion engines on a designed and purpose-built stand outside of the combustion engine. Various designs and injector nozzles are made from various types of alloy steel for marine and automotive piston internal combustion engines fueled with distillation or residual fuels, and are tested. The research concerned conventional elements for the injection apparatus as well as electronically controlled subsystems. Precision pairs of injection equipment are selected for the tests: new ones are employed after the storage period and operated in natural conditions. The elements dismantled from the internal combustion engines are tested in the presence of fuel or calibration oil of similar properties. The maximum static frictional forces under the hydrostatic loading are measured, alongside the parameters for the dynamic movement of the nozzle needles from bodies of the injector nozzle as time, speed, acceleration and dynamic force. The influence of the angular position of the needle in relation to the bodies of the precision pairs conventional internal combustion engines, the diametral clearance between the nozzle body and needle, and the surface conditions on the values of the maximum friction force are also presented. Errors in shape and position result in the uniqueness of the friction force at the mutual angular position of the needle in relation to the nozzle body, and the decrease in diametral clearance and deterioration of the surface state increase the friction losses. A model was elaborated of the influence of various factors on the value of the maximum friction force.

Mechanism analysis of the influence of nanoparticles on the convective heat transfer coefficient of traditional fluids

With the continuous progress of science and technology, the heat transfer performance of electronic chips and internal combustion engine pistons is increasingly required by industry. The traditional pure liquid can hardly meet the current heat transfer requirements, and it is known that the heat transfer performance of solids is always better than that of fluids. Therefore, adding solid particles to the fluid has a positive effect on the heat transfer performance of the fluid. In this paper, an experimental system is established to study the heat transfer performance of SiO2-water nanofluids, and the variation of each physical parameter and convective heat transfer coefficient of SiO2-water nanofluids flowing in a circular tube at different volume fractions is measured. The microscopic mechanism of the enhanced heat transfer of nanofluids is also analyzed from the perspective of nanoparticle's micro-motion by numerical simulation. The results show that the convective heat transfer coefficients of nanofluids gradually increase with increasing volume fraction of nanoparticles under the same conditions. The convective heat transfer coefficients of SiO2-water nanofluids with volume fractions of 0.5 %, 1 %, and 2 % increase by 15.1 %, 25.9 %, and 36.8 %, respectively, compared with pure water. Then the extent of the effect of nanofluid physical parameter changes and nanoparticle micro-motion on the improvement of nanofluid heat transfer performance is analyzed. It is found that the micro-motion of nanoparticles has a greater effect on the enhanced heat transfer of nanofluids compared to the variation of physical parameters. It is also found that the conventional convective heat transfer coefficient formulation for single-phase flow is not applicable to calculate the convective heat transfer coefficient of SiO2-water nanofluids. Therefore, the new formulations based on the convective heat transfer coefficient of SiO2-water nanofluids in different flow regimes are established.

Influence of the thermal deformation on the lubricating performance of the piston-gudgeon pin interface in an internal combustion engine

This contribution describes a methodology to evaluate the influence of bellmouth profiles on the elastohydrodynamic behaviour of the contact interface between the gudgeon pin and the piston of a high-performance internal combustion engine. First, a thermo-mechanical simulation is performed to evaluate the piston bosses thermal strains. Consequently, a Multibody elastohydrodynamic model is set up to evaluate the tribological behaviour of this lubricated interface considering a perfectly cylindrical shape of the piston bosses and their thermal deformation. Then, a preliminary bellmouth profile is adopted and a second Multibody model is performed. Nevertheless, the results, together with issues encountered analysing some tested pistons, suggest that modifications of piston bosses have to be introduced. Finally, an optimised bellmouth geometry is proposed and analysed.

Modelling of a Conventional Piston of a Single Cylinder Four-Stroke Diesel Engine by Using SolidWorks

This paper presents a 3D modelling of a conventional piston of a single cylinder four-stroke diesel engine using ZS1115NM diesel engine specification. Piston in internal combustion engine (ICE) is a circular piece of metal which converts the rotary movement of the crankshaft into reciprocating motion thereby exerting a force on the air-fuel mixture in the cylinder. It converts thermal energy into mechanical energy in an internal combustion engine (ICE). The methodology applied was analytical design and modelling of the piston using SOLIDWORKS 2013 3D Computer Aided Design (CAD) software. This method was used because it provided a step by step designing of the various elements of the piston. The material chosen for the piston is an aluminium alloy designated as A92618 or simply A2618, due majorly to its high coefficient of thermal expansion (CTE) which enables the piston withstand high thermal stress without cracking or failure. Another important reason is that it has a high thermal conductivity (approximately 3 times than that of cast iron). It is seen that with given engine specification a suitable material for designing a conventional piston is chosen and the model manufactured. Keywords— 3D modelling, ZS1115NM, Internal combustion engine, SOLIDWORKS 2013, A2618, Coefficient of thermal expansion

Study of technological properties of new aluminum-calcium alloys for pistons of internal combustion engines

The results of studies of the casting properties of aluminum-calcium alloys in comparison with known silumins are presented. The alloys were prepared in a resistance electric furnace based on pure components and ligatures. The pouring was carried out at temperatures of 700 and 780 oC for silumins and aluminum-calcium alloys, respectively, obtaining flat ingots for subsequent remelting and casting of samples. All samples were poured with the same superheat above the liquidus temperature of 100 oC. It is shown that alloys with calcium (both eutectic and hypereutectic) are not inferior to widely used silumins in terms of fluidity, hot brittleness, and form fillability. For the first time, the parameters of difficult shrinkage were determined in a T-shaped sample of aluminum-calcium alloys in comparison with silumins. It is shown that eutectic alloys have comparable values of linear shrinkage with eutectic silumins, and the shrinkage of the hypereutectic alloy Al – 6% Ca – 3% Mn exceeds the shrinkage of the hypereutectic silumin AK18 by 1.5 times (1.5 and 1%, respectively). A high deformation plasticity during hot and cold rolling of the Al6Ca3Mn hypereutectic alloy has been established. The overall reduction ratio after applying both rolling methods exceeded 95%. The primary crystals retained their compact size and shape. It has been established that the strength properties of cold-rolled sheets from the Al6Ca3Mn hypereutectic alloy correspond to the strength values of the AD31 industrial aluminum alloy, which allows to consider it promising in those industries where a combination of high manufacturability with reduced thermal and electrical conductivity is required.

Production process automation of internal combustion engine (ICE) pistons from hypereutectic silumins by injection molding with crystallization under pressure, followed by isothermal forging

A technology for the production of ICE pistons from aluminum alloys with a silicon content of 18 % is proposed. A method for pressing a crystallizing metal by pressure on a horizontal hydraulic press in order to obtain piston blanks for subsequent isothermal forging is developed. The pressing process is controlled by a computer control system embodied through the use of the modern industrial logic controllers and software. An interface for program control is developed. It indicated that the use of modern process control systems makes it possible to control the formation of the final product properties in real time. Keywords automation, computer control system, internal combustion engine pistons, isothermal forging, crystallization, pressure, mechanical properties of metal products

Дослідження напружено-деформованого стану іонноазотованих зразків із покриттям в умовах ізотермічної та термоциклічної повзучості методом кінцево-елементного аналізу

One of the advanced methods of increasing the thermal stability of the pistons of internal combustion engines is ionic nitriding (ion-plasma nitriding). At the same time, the study of the stress - strain state of a sample of aluminum alloy with heat - protective diffusion ion - nitrided layers under conditions of thermocyclic loading (simultaneous action of load and temperature) is an urgent task. The application of the finite element analysis method makes it possible to predict the operation of the parts of the cylinder-piston group, namely the time and place of the crack when the load and temperature change. When calculating the stress-strain state, the peculiarities of their geometric parameters, properties of structural material, type of calculation (static, thermal, etc.), and conditions of force and temperature load acting on them were taken into account. The calculation was performed using real experimental samples. The method of calculating the stress-strain state of the composition "base - coating" taking into account operational and technological factors consists of several stages: solving the problem of non-stationary thermal conductivity to determine the residual stresses resulting from coating; determination of stresses from power and temperature load; obtaining the stress-strain state by the method of superposition. Using the finite element analysis method, the stress-strain state of the aluminum sample was evaluated, both without hardening and with a heat-protective diffusion ion-nitrided surface layer from simultaneous exposure to load and temperature, namely under conditions of thermocyclic creep. To more accurately determine the equivalent stresses, the calculations were performed on 1/8 of the sample. Comparative evaluation of the stress-strain state of 1/8 of the sample of aluminum alloy AL21 and with a reinforced surface layer was performed using the software package NASTR. Thus, based on the analysis of the stress - strain state of the aluminum alloy sample with heat - protective diffusion ion - nitrided layers under thermocyclic loading (simultaneous action of load and temperature) it is established that a significant part of equivalent stresses is perceived by the strengthened surface layer. This confirms the increase in the resistance of the composition "base-coating" of both isothermal and thermocyclic creep. In addition, with the help of the finite element analysis method, it is possible to predict the operation of the parts of the cylinder-piston group, namely the time and place of the crack when the load and temperature change.

A stochastic topology optimization algorithm for improved fluid dynamics systems

Abstract The use of topology optimization in the design of fluid dynamics systems is still in its infancy. With the decreasing cost of additive manufacture, the application of topology optimization in the design of structural components has begun to increase. This paper provides a method for using topology optimization to reduce the power dissipation of fluid dynamics systems, with the novelty of it being the first application of stochastic mechanisms in the design of 3D fluid–solid geometrical interfaces. The optimization algorithm uses the continuous adjoint method for sensitivity analysis and is optimized against an objective function for fluid power dissipation. The paper details the methodology behind a vanilla gradient descent approach before introducing stochastic behavior through a minibatch-based system. Both algorithms are then applied to a novel case study for an internal combustion engine's piston cooling gallery before the performance of each algorithm's resulting geometry is analyzed and compared. The vanilla gradient descent algorithm achieves an 8.9% improvement in pressure loss through the case study, and this is surpassed by the stochastic descent algorithm which achieved a 9.9% improvement, however this improvement came with a large time cost. Both approaches produced similarly unintuitive geometry solutions to successfully improve the performance of the cooling gallery.

Design Considerations and Performance Estimation of Free Piston Internal Combustion Engines in Catalytic and Small-scale Environments

Design Considerations and Performance Estimation of Free Piston Internal Combustion Engines in Catalytic and Small-scale Environments

Технические и экологические аспекты новых требований к эксплуатационным свойствам перспективных моторных масел

The modern development of transport is at the stage of energy transition to its zero-carbon operation with the use of alternative energy sources instead of traditional liquid fuel. It is assumed that the operation of transport using electric motors and hydrogen fuel cells in the future will be able to represent a significant segment of the global economy. Manufacturers of heavy-duty vehicles and buses are currently actively investing in so-called carbon neutrality technologies and are activating the technical capabilities of options for using electric vehicles for heavy operating conditions. At the same time, along with the electrification of vehicles, the popularity of traditional piston internal combustion engines remains, including in hybrid car models. The new environmental regulations Euro-7, which are part of the European "Green Agreement", include stricter emission standards for all gasoline and diesel cars, vans, trucks and buses. This is part of the EU's commitment to support the goal of achieving carbon neutrality by 2050. In connection with the latest achievements in the design of diesel engines, the development of a new category of PC-12 engine oil for heavy-duty diesel engines is officially underway in order to replace the oils of the existing categories CK-4 and FA-4 according to API. The category of oils in the projected specification is planned to be divided into subcategories that provide conditions for their use in heavy-duty transport: off-road conditions, including those with a high temperature load, assuming a high oil viscosity at 150 oC and a shear rate of 106 s-1 (High Temperature High Shear - HTHS), and highway operation. It is assumed that the new PC-12 specification will provide increased thermal-oxidative stability of oils and improved compatibility with elastomers in both subcategories, as well as wear tests with the inclusion of new methods.

Contributions towards improving the displacement and strain responses of an internal combustion engine piston through topology optimisation

State-of-the-art parts require state-of-the-art engineering. On this occasion, in this research paper, contributions towards improving the displacement and strain responses of an internal combustion engine piston are presented. The load case scenario and the topology constraints are established in the beginning. In the following stage, the reference values are defined with the means of an FEA simulation. Afterwards, the topology of the piston is optimised. To quantify the improvements, a comparison analysis was made in the ending part of this paper. This study aims to reduce the displacement and strain responses of an internal combustion engine piston through topology optimisation.

Improving the performance of cast iron bushings of small-sized marine diesel engines

An increase in the performance and wear resistance, a decrease in the running-in time of piston internal combustion engines of high-speed marine small-sized diesel engines by applying boron-containing coating and copper coating to the cylinder surface are considered. An processing unit was designed for applying pastes when boriding the working surface of the sleeve with laser heating. Keywords: friction pair, internal combustion engine cylinder, piston sleeve, wear resistance, performance, surface roughness, running-in. nurik909@mail.ru

Assessment of Computer-Aided Design Tools for Topology Optimization of Additively Manufactured Automotive Components

The use of Topology Optimization techniques has seen a great development since the last decade. The principal contributor to this trend is the widespread use of Additive Manufacturing technologies to effectively build complex and performant structures over different settings. Nevertheless, the use of Topology Optimization in Design for Additive Manufacturing processes is not simple and research aims to fill the gap between theory and practice by evolving at the same time both approaches, workflows, and design software that allow their implementation. Since a strong connection between methodologies and tools exists, this work proposes a method to assess computer-aided design tools or platforms. This can be applied to sustain the key phase for selection and adoption of the computer-aided tools in industrial settings embracing Additive Manufacturing. The workflow for Topology Optimization implementation, the structure of the proposed evaluation approach, and its application, are presented to demonstrate effective usability. The automotive case study is the redesign of internal combustion engine piston to benefit of metal Additive Manufacturing based enhanced product performance. A preliminary finite element model is defined and a Topology Optimization based redesign is concurrently set up through four different commercial computer-based platforms. The method accounting for the assessment of required operations for the design optimization is applied to perform the tools selection phase.

Experimental Analysis of the Influence of the Application of TiN, TiAlN, CrN and DLC1 Coatings on the Friction Losses in an Aviation Internal Combustion Engine Intended for the Propulsion of Ultralight Aircraft

Currently, there are many methods of reducing the friction losses of the main components of an internal combustion piston engine. The operating conditions of internal combustion piston engines intended for the propulsion of ultralight aircraft differ significantly from those prevailing in the case of using these engines for the propulsion of vehicles. There are many studies on the influence of selected anti-wear coatings on the friction coefficients when using various lubricants, measured via tribometers. Unfortunately, the conditions obtained in the laboratory significantly differ from those prevailing in an engine operating under external conditions. The study investigated the influence of a change in the tribological parameters of TiN, TiAlN, CrN and DLC1 anti-wear coatings on the moment of resistance to the piston movement of an aircraft engine. The operating parameters of a real engine working in an aircraft were simulated. The main focus was on the coating layers of the sliding surfaces of the piston rings and the cylinder running surface. The properties of the coatings affect the correlation of the scale of the adhesion and cohesion phenomena of the oil to the opposite planes, and this determines the nature of the changes in the moment of resistance to engine motion. As it is commonly known, with an increase in the value of the maximum pressure of the working medium in the combustion chamber, the share of mixed friction in liquid friction increases, similar to the high oil temperatures occurring in aircraft engines. Therefore, there is a justified need to supplement the research in the field of analyzing the characteristics of the torque of resistance to motion for these engines, in particular in the field of the usable rotational speeds of the crankshaft. Applicable anti-wear systems based on selected coatings can significantly improve operational safety and noticeably reduce fuel consumption.