Internal Combustion Engine Cylinder Research Articles

Dynamics of change in the polytropic exponent in the expansion stroke of diesel

In the article is considered the problem of achieving the optimal duration of the working stroke of a diesel engine piston during the expansion process and obtaining the maximum efficiency coefficient (EC). For this purpose, a hypothesis was put forward about the pumping action of the piston on the flow of expanding gases during the power stroke of an diesel internal combustion engine (ICE) as the piston moves from upper dead point (UDP) to bottom dead point (BDP).At a certain moment of expansion, the rate of the flow of expanding gases turns out to be equal to the rate with which the same flow is slowed down by the moving piston.The equality of these rates leads to the formation of a flow break line and has a significant impact on the nature of the change in the polytropic exponent; the value of the exponent becomes equal to one: n = 1. This indicates that the optimum duration of the engine’s working stroke has been achieved and corresponds to the maximum power that can be removed during the diesel engine’s operating cycle. An experimental relation was obtained between the initial p1 and final p2 pressures in the cylinder during gas expansion with the gas flow rate and the rate of deceleration of this flow due to the pumping action of the piston. An equation for the continuity of gas flow has been compiled for the process of gas expansion in the cylinder of an ICE with closed gas exchange organs. Based on this equation, the numericalvalue of the acceleration of gravity in the cylinder of ICE is obtained: gф ≈ 8,7 м/с2 < g, which confirms the pumping action of the piston. A theoretical (and graphical) dependence of the polytropic process exponent on the flow rate of expanding gases is obtained. The dependence allows to calculate the polytropic exponent and establish the gas relaxation period, indicating the achievement of the optimal duration of the piston stroke.

CRITERIA FOR ASSESSING THE EFFECTIVENESS OF TRANSPORT POWER PLANTS DECARBONISATION IN ACCORDANCE WITH IMPLEMENTATION OF THE SUSTAINABLE DEVELOPMENT CONCEPT

The directions of restoration and further development of the energy sector in Ukraine are considered in accordance with power plants with internal combustion engines, taking into account the widespread implementation of the Sustainable Development concept, which allows solving existing modern social, economic and environmental problems. For Ukraine, taking into account the economic opportunities and selected priorities for the chosen path of development, it is necessary at this time to choose gradual and specific directions to implement the Sustainable Development concept. The most priority areas of practical implementation of the concept are determined and it is indicated that the effectiveness of this implementation is associated with the development of the industry on the basis of the fourth and fifth industrial revolutions (Industry 4.0 and Industry 5.0). One of the main tasks in solving the problems of the concept is to ensure the environmental component. Notwithstanding the noted progress in improving the environmental efficiency of internal combustion engines, further attention needs to be paid to the task of spreading the introduction of “green energy”, i.e. decarbonisation – reducing greenhouse gas emissions into the environment (CO2). The issue of decarbonisation in the future should be given the greatest attention both in the development and in the manufacture and operation of engines. It is shown that the assessment of the impact of CO2 emitted with the exhaust gases of internal combustion engines into the environment is carried out taking into account the model of operation of engines and the justification of the introduced adjustments. A new criterion is proposed, which is called: “ICE criterion of environmental thermal pollution”, which is proposed for use in studies to assess the effectiveness of the implementation of decarbonisation strategies in all modes of transport at implementation of the Sustainable Development concept in global transport power plants. A method for determining the efficiency of physical and chemical processes of mixture formation and combustion in internal combustion engine cylinders is proposed when using hybrid fuel with “green hydrogen” as its component, which allows determining the dependence of hydrogen influence on the level of engines effective performance and formation of harmful emissions in exhaust gases.

Influence of Compression Ratio on Pressure in the Cylinder of Internal Combustion Engine

Influence of Compression Ratio on Pressure in the Cylinder of Internal Combustion Engine

Three-dimensional surface temperature measurement using lifetime-based phosphor thermometry

Abstract In this study, we propose a three-dimensional (3D) surface temperature measurement method based on the principle of stereoscopic 3D reconstruction and the dependence of phosphorescence lifetime on temperature. A 385-nm UV(Ultraviolet) light was used as the excitation light, and two high-speed cameras were used as the detectors. The phosphor MFG (Mg4FGeO6: Mn4+) was mixed with the binder HPC and sprayed onto the tested 3D surface. The natural texture generated by the surface roughness of the phosphor coating was used as a feature for cross-correlation calculations. The digital image correlation (DIC) algorithm was used to match these feature positions in the phosphorescent images from the two cameras. The effects of the excitation angle and detecting angle were analyzed. The results indicate that the temperature measurement based on phosphorescent lifetime was not affected by the excitation and detecting angle. The method was validated on a turbine blade as an example of a 3D surface to demonstrate the capability. A comparison of the measurement results with the thermocouples proves that the current method can successfully measure the temperature on 3D surfaces with a maximum difference of 1.63°C. The spatial accuracy of the method was obtained by comparing with the measurement results of a 3D scanner, which shows that the maximum absolute error of the 3D reconstruction was 0.350 mm. The current study proposes a promising 3D surface temperature measurement method, which is expected to be widely used in gas turbine blades, Internal Combustion (IC) engine cylinders, complex curved heat exchangers, and other fields due to its non-contact measurement, low susceptibility to infrared radiation interference, high measurement accuracy, and ability to withstand harsh environments.

Modeling of thermodynamic processes in internal combustion engine cylinder during cranking in compression measurement tests

The thermodynamics of in-cylinder processes of the internal combustion engine in cranking mode when measuring compression were examined. Analysis of various theoretical models and comparison of known data showed that the problems of constructing mathematical models of the engine operating cycle remain unresolved. The vast majority of practical data and recommendations for measuring cylinder compression are based on empirical knowledge, numerous experiments and tests. In accordance with this, there is a need for computational models of the compression measurement process and their theoretical justification. To solve the identified problems, a mathematical model of the thermodynamic processes in the cylinder was developed. Unlike existing ones, the model describes the processes in the cylinder step by step, taking into account the real nature of the intake-exhaust processes, air leakage through the interfaces of parts and heat exchange with the walls. Using modeling, the main patterns of changes in compression depending on the modes, the nature of damage to the associated parts of the valve mechanism and cylinder-piston group, the amount of leakage and engine temperature were found. Based on the results of the study, the properties of the model which make its use effective in diagnosing and monitoring the technical condition of engines in operation were concluded.

Method for expert evaluation of the technical con-dition of the cylinder-piston group of automotive engines after hydrolock

Problem: The study examines the thermogasdynamic process within an internal combustion engine cylinder during cold cranking mode while measuring compression. Analysis of various models and comparison of known data revealed unresolved challenges in constructing mathematical models of the engine operating cycle. The vast majority of practical data and recommendations for compression measurement in a cylinder are based on empirical knowledge, numerous experiments, and tests. Consequently, there arises a need for computational models of the compression measurement process and their theoretical justification, particularly in cases where engine damage occurs during hydrolock in a cylinder. Methodology. To address the identified issues, a mathematical model of the thermogasdynamic process within the cylinder during cold cranking while measuring compression was developed. Originality. Unlike existing models, this model describes the processes in the cylinder step by step, considering the real nature of intake-exhaust processes, air leakage through part interfaces, and heat exchange with the walls. Through modeling, the main patterns of compression changes depending on the modes and the nature of damage to associated parts of the valve mechanism and the cylinder-piston group were identified, including deformation of the connecting rod during hydraulic lock due to liquid entering the cylinder. Practical value. Based on the study results, it was concluded that the model's properties make it effectively applicable in diagnosing and monitoring the technical condition of automotive engines during operation.

A Two-Time-Scale Turbulence Model and Its Application in Free Shear Flows

A novel three-equation turbulence model has been proposed as a potential solution to overcome some of the issues related to the k–ε models of turbulence. A number of turbulence models found in the literature designed for compressed turbulence within internal combustion engine cylinders tend to exhibit limitations when applied to turbulent shear flows, such as those occurring through intake or exhaust valves of the engine. In the event that the flow is out of equilibrium where Pk deviates from ε, the turbulence models require a separate turbulence time-scale determiner along with the dissipation, ε. In the current research, this is accomplished by resolving an additional equation that accounts for turbulence time scale, τ. After presenting the rationale behind the model, its application to three types of free shear flows were given. It has been shown that the three-equation k–ε–τ model outperforms the standard k–ε model as well as a number of two-equation models in these flows. Initially, the k–ε–τ model handles the issue of the plane jet/round jet anomaly in an effective manner. Secondly, it outperforms the two-equation models in predicting the flow behavior in the case of plane wake, one that is distinguished by its weak shear form.

Cooling enhancement for engine parts using jet impingement

A computational study has been performed to evaluate the use of jet impingement for cooling applications in the automotive industry. The current study uses an entire internal combustion engine cylinder with its components as a computational domain. An unsteady numerical solution for the Navier-Stokes equations was carried out using Improved Delayed Detached Eddy Simulation (IDDES). The volume of fluid approach is proposed to track and locate the liquid jet surface that is in contact with the air. The conjugate heat transfer approach is used to link the heat transfer solution between the fluid and the solid. The boundary conditions that are employed in the study are provided from lab experiments and one-dimensional simulations. The cooling jet in this study targets the hottest region in the piston, i.e., the region underneath the exhaust valve. Three nozzle sizes with flows at different Reynolds numbers are chosen to examine the thermal characteristics of the cooling jet. The computational study reveals that for a specific Reynolds number, the smaller diameter nozzle provides the highest heat transfer coefficient around the impingement point. The maximum relative velocity location at the impingement point slightly leads the location of the maximum Nusselt number. The maximum temperature in the piston decreases by 7% to 11% as the nozzle diameter changes from 1.0 to 3.0 mm for a jet Reynolds number of 4,500. If a correct selection is made for the nozzle size, the cooling jet can be efficiently used to reduce the temperature and alleviate the thermal stresses in the piston in the region underneath the exhaust valve where the maximum temperature occurs.

Test bench development and implementation for experimental determination of mechanical losses in single cylinder internal combustion engines

As mechanical efficiency has great relevance in the alternative engine performance, the authors research in the development of testing facilities to characterize the sources of engine mechanical losses. The present paper deals with the realization of a hardware platform to conduct experimental studies in small combustion engines to experimentally characterize the mechanical losses of a single-cylinder internal combustion engine by means of the indicated diagram and motoring methods. The system was completed by means of an electrical motor-generator coupled to a single-cylinder air-cooled spark ignition engine, a self-developed electronic hardware control, and a PC-based instrumentation and data acquisition system. Specifications of load-motoring-starting system, including the description of the proprietary electronic load regulation system, are detailed. Also, the instrumentation system of in-cylinder and intake pressures; Temperatures of intake air, exhaust gases, lubricant oil, and engine block; effective torque and crankshaft position are described, including the signal acquisition system. The methodologies for indicated diagram and motoring method are described, mentioning the required measurements to apply each method and the engine load-temperature considerations when an engine is tested in fired or motored conditions. The platform was used to study the mechanical losses of the engine under motored and fired conditions under a wide range of rotational speeds and throttle openings, allowing to draw conclusions about the operating features of the developed test bench in itself, and also about the mechanical losses of the engine tested. Initially, samples of cylinder pressure, torque, intake pressure as function of crank angle and indicate diagram were obtained, showing similar waveforms present in related literature. Then, variations of the aforementioned temperatures against rotation speed and throttle opening and results for the mechanical losses determined by indicated diagram and motoring methods are shown. Finally, two empirical correlations are proposed to estimate the mechanical losses. In the future the hardware platform will be utilized to investigate in-cylinder engine parameters, detailed thermal and mechanical engine performance

A Novel Neural Network with the Ability to Express the Extreme Points Distribution Features of Higher Derivatives of Physical Processes

Higher derivatives are important to interpret the physical process. However, higher derivatives calculated from measured data often deviate from the real ones because of measurement errors. A novel method for data fitting without higher derivatives violating the real physical process is developed in this paper. Firstly, the research on errors’ influence on higher derivatives and the typical functions’ extreme points distribution were conducted, which demonstrates the necessity and feasibility of adopting extreme points distribution features in neural networks. Then, we proposed a new neural network considering the extreme points distribution features, namely, the extreme-points-distribution-based neural network (EDNN), which contains a sample error calculator (SEC) and extreme points distribution error calculator (EDEC). With recursive automatic differentiation, a model calculating the higher derivatives of the EDNN was established. Additionally, a loss function, embedded with the extreme points distribution features, was introduced. Finally, the EDNN was applied to two specific cases to reduce the noise in a second-order damped free oscillation signal and an internal combustion engine cylinder pressure trace signal. It was found that the EDNN could obtain higher derivatives that are more compatible with physical trends without detailed differentiation equations. The standard deviation of derivatives’ error of the EDNN is less than 62.5 percent of that of traditional neural networks. The EDNN provides a novel method for the analysis of physical processes with higher derivatives compatible with real physical trends.

Synergy Study Between a Lubricant Oil Layer and a Microstructural Graphite to Reduce Friction and Wear of a Thermally Modified Low-Carbon Gray Cast-Iron Cylinder Liner

The results of a sliding wear tests on base and thermal treated gray cast iron (GCI) samples from internal combustion engine cylinder liner are reported here for dry and lubricated conditions. A thermal treatment was applied to samples of 10 x 10 mm to avoid the effect of residual stress and to obtain the microstructure of interest. Tribological tests were carried out up to 27000 cycles at room temperature. A frequency of 15 Hz, a stroke amplitude of 6 mm, and a maximum contact pressure of 1.12 GPa were selected. Under the unlubricated settings, a noticeable decrease in friction coefficient and specific wear rate are attributed to the appearance of irregular graphite nodules in the heating–quenching process. The significance of thermal treatment applied to low carbon cast iron in the derived self-lubricating function and its synergistic role with the oil lubricant is discussed. In this context, this work illustrates, for the first time, how the change in the morphology from flake graphite to irregular nodule graphite positively determines the reliability of gray casting irons.

Effect of the helical-spiral shroud intake valve on flow in cylinder of internal combustion engine

In this paper, we proposed a method to increase the mixing performance of gasoline and intake air by attaching a helical-spiral shroud to the intake valve. The effect of the height and revolution number of helical-spiral shroud on the generation of swirl in the engine cylinder are analyzed. The height is 20 and 25 mm, and the revolution number is changed to 1 and 1.5 turns. A three-dimensional simulation model using the shear stress transport k–ω model is used as the turbulence model to predict the air flow characteristics through the intake valve and engine cylinder in the intake and compression strokes. As a result, the helical-spiral shroud intake valve (HSSIV) generally increases the swirl ratio compared to the general valve, and the swirl ratio in the HSSIV with a height of 20 mm and revolution number of one turn has a maximum value of 77 around 90CAD. It also shows that HSSIV has little effect on the volumetric efficiency reduction while increasing the swirl ratio from different geometrical properties than the conventional shroud valves.

LES-Predicted Flow Patterning in a Newly-Designed Reference Test Sample with Relevance to IC Engine-Related Cooling Channels

<div class="section abstract"><div class="htmlview paragraph">A test sample configuration with a circular cross-section has been conceptualized to reproduce all geometrically relevant flow-guided elements - straight segments, deflections, bifurcations, impingement regions, confluence - as they can also be found in the cooling systems of realistic Internal Combustion (IC) engines. This newly-designed reference test sample is termed as Water Spider Geometry (WSG), with the shape inspired by the flow guidance around an IC engine cylinder head. Computational investigations are carried out within the framework of a BMWi (German Federal Ministry for Economic Affairs and Energy) project by applying a well-resolved, highly comprehensive Large Eddy Simulation aiming at providing a meaningful assessment of the isothermal flow topology within the WSG. The basis forms a fully-hexahedral, block-structured grid arrangement comprising 290 million cells with the results considered to be a reference solution for further investigations.</div></div>

Analytical study regarding topological optimisation of an internal combustion engine cylinder block

The continuous rush for development has led the world of automotive engineering to progress that seemed unimaginable just a few years ago. This research paper examined the impact of a topological optimisation of an internal combustion engine block. Starting with the initial conditions, a constraint and load case scenario was established, after which a FEA simulation was conducted to set the reference values. In the last part of the research paper, test results are head-to-head compared to determine and quantify the improvements. This study aims to reduce the volume of the optimised part and increase its overall rigidity. The topology optimisation process represents a good solution for “what if” scenarios. By varying optimisation constraints, the designers can quickly check if the mass reduction of the analysed part is worth the changes.

Smart Modulation for Control Systems with High Regulation Capabilities for Cooling Systems Optimisation and Carbon Footprint Reduction in Industry

Nowadays, every large enterprise is concerned about reducing CO2 emissions. Along with legislation, management, packaging, and transportation decisions, optimising the operation of automated systems in the industry is important. Overheating processes or large cooling systems of one machine during product assembly may seem minor but at the industry level it is quite significant. Either an optimisation of cooling systems or an intelligent machine control which will prevent heat strokes and allow the transition to passive cooling of the whole system is an important issue for improving machine tools efficiency and contributing therefore to CO2 reduction in the industry sector. This research is a transitional phase from the creation of a control system to solve the problems of resonance in the control of systems with parallel piezo kinematics, which were designed to automate the iterative process of non-circular drilling with a precise shape and the subsequent research on the implementation of smart control to optimise the cooling of industrial machines. The total dynamics of the example system in this research is unknown and consists of the dynamics of electrical converters, piezo kinematics, and mechanics. The control signal of this system is generated by the model of the system state with assumptions and simplifications in combination with machine learning techniques considering the previous errors of the transient characteristics with the possibility of re-drilling without damaging the workpiece and with possibility of further trainings to eliminate the iterative process in general. Algorithms for further training at different resonances with a drilling depth change for cylinders of internal combustion engines are offered. These algorithms are proposed for accurate transmission of the input signal amplitude even in resonant situations, power optimisation, increase the system efficiency, as well as reducing the carbon footprint when used in industry in specific applications.

Effects of Temperature on the Evolution of Yield Surface and Stress Asymmetry in A356-T7 Cast Aluminium Alloy.

As the electrification of vehicle powertrains takes prominence to meet stringent emission norms, parts of internal combustion engines like cylinder heads are subjected to an increased number of thermal load cycles. The cost-effective design of such structures subjected to cyclic thermo-mechanical loads relies on the development of accurate material models capable of describing the continuum deformation behaviour of the material. This study investigates the effect of temperature on the evolution of flow stress under cyclic loading in A356-T7 + 0.5% Cu cast aluminium alloy commonly used in modern internal combustion engine cylinder heads. The material exhibits peak stress and flow stress asymmetry with the stress response and flow stress of the material under compressive loading higher than under tension. This peak and flow stress asymmetry decrease with an increase in temperature. To compare this stress asymmetry against conventional steel, cyclic strain-controlled fatigue tests are run on fully pearlitic R260 railway steel material. To study the effect of mean strain on the cyclic mean stress evolution and fatigue behaviour of the alloy, tests with tensile and compressive mean strains of +0.2% and −0.2% are compared against fully reversed (Rε = −1) strain-controlled tests. The material exhibits greater stress asymmetry between the peak tensile and peak compressive stresses for the strain-controlled tests with a compressive mean strain than the tests with an identical magnitude tensile mean strain. The material exhibits mean stress relaxation at all temperatures. Reduced durability of the material is observed for the tests with tensile mean strains at lower test temperatures of up to 150 °C. The tensile mean strains at elevated temperatures do not exhibit such a detrimental effect on the endurance limit of the material.

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

Developing technology of creating wear-resistant ceramic coating for internal combustion engine cylinder sleeve

This paper presents the results of testing a wear-resistant ceramic coating on the work surface of an internal combustion engine (ICE) cylinder’s sleeve. A combined coating formation technology is described that consists in applying an aluminum layer to the sleeve’s work face by gas dynamic spraying and then covering this face with a ceramic layer by microarc oxidation (MAO). A tenfold reduction in the reinforced sleeve has been determined by the accelerated comparative wear rig tests of reference (new) sleeve-piston ring coupling specimens and reinforced specimens with a combined coating. The supplementation of nanoparticle admixture to MAO coating reduces the friction factor between the cylinder sleeve face and the piston ring by 25-30%. The proposed technology can be used to reinforce work surfaces of new cylinder sleeves and recover worn out ones.

Improving Tribological Behavior of ICE’s Cylinder Surface by Laser Surface Texturing (LST)

This study investigates the effect of laser surface texturing (LST) on the friction and wear behavior of grey cast iron (GCI) of internal combustion engine (ICE) cylinder in lubricated conditions. The dimples having diameter of about (58-60) μm and depth of about 10 μm were created on the surface with various dimple densities ranging from 5 to 50%. A ball-on-disc friction tests were performed for all the specimens under 5W30 and 15W50 oils with different viscosities. The tests were carried out at a load of 5N and speed of 5cm/s. The coefficient of friction of the dimpled specimen was reduced significantly by approximately 32% as compared to the polished speciemen. Specimen with 15% dimples exhibits the lowest coefficient of friction of all the dimpled specimens in both low and high viscous oils. The high viscous oil found to be more efficient regarding coefficeint of friction compared to the low viscous oil. The degree of wear of the specimens was analyzed on the basis of wear scar developed on the counter surface as it supplements the wear during the friction tests. The resistance to wear of the sliding specimens was found to be increased in high viscous oil compared to that in low viscous oil.

Gaseous Lubricant in the Cylinders of Internal Combustion Engines

Gaseous Lubricant in the Cylinders of Internal Combustion Engines