Diesel Engine Piston Research Articles

Experimental recording of unsteady temperatures in the piston of a high-speed diesel engine under transient conditions

Unsteady thermal loads on combustion chamber parts in a supercharged diesel engine dictate their service life. In practice, it is crucial to know the dynamic behaviour of temperatures and their gradients for automobile and tractor diesels that often change their operating conditions during running. Most reliable information can be obtained by experimental recording of temperatures on a test bench during engine tests. This information is used for mathematical modelling of temperature fields and temperature stresses. The objective of this research effort is the experimental recording of unsteady piston temperatures when the diesel load is increased and reduced rapidly. Thermocouples were chosen, and their thermal response was evaluated to increase the accuracy of recording piston temperatures. In addition, locations for installing thermocouples were chosen. A continuous-type current sensor was developed and refined to connect the hot junctions of the thermocouples with the recording instrumentation. The unsteady temperatures of the piston (aluminium alloy AL 25) in a high-speed diesel engine were recorded experimentally. Piston temperatures were recorded for cases when the load was increased and reduced rapidly. Treatment of experimental data has yielded the basic dynamic characteristics of the temperature fields in the diesel piston).

Experimental recording of unsteady temperatures in the piston of a high-speed diesel engine under transient conditions

Unsteady thermal loads on combustion chamber parts in a supercharged diesel engine dictate their service life. In practice, it is crucial to know the dynamic behaviour of temperatures and their gradients for automobile and tractor diesels that often change their operating conditions during running. Most reliable information can be obtained by experimental recording of temperatures on a test bench during engine tests. This information is used for mathematical modelling of temperature fields and temperature stresses. The objective of this research effort is the experimental recording of unsteady piston temperatures when the diesel load is increased and reduced rapidly. Thermocouples were chosen, and their thermal response was evaluated to increase the accuracy of recording piston temperatures. In addition, locations for installing thermocouples were chosen. A continuous-type current sensor was developed and refined to connect the hot junctions of the thermocouples with the recording instrumentation. The unsteady temperatures of the piston (aluminium alloy AL 25) in a high-speed diesel engine were recorded experimentally. Piston temperatures were recorded for cases when the load was increased and reduced rapidly. Treatment of experimental data has yielded the basic dynamic characteristics of the temperature fields in the diesel piston).

Thermo-mechanical evaluation of plasma sprayed YSZ-based multi-layered thermal barrier coatings

The multi-layered YSZ, NiCoCrAlY, Cr2O3 and Al2O3 coatings of varying thickness (200 μm-400 μm) have been investigated for thermal barrier coating (TBC) application. Plasma spray technique has been utilised on piston crown to optimise the thermal fatigue life in view to reduce the heat losses. Four types of TBC overlay each with a 100 μm NiCrAlY bond coat were deposited on the A336 aluminium alloy substrate cut out of the diesel engine piston. The phase composition of coatings before and after the thermal shock testing was analysed by XRD and the lattice strain analysis was performed by Williamson-Hall analysis. It was observed that among the considered multi-layered coating configurations, those with 300 μm YSZ and 200 μm Cr2O3 top coat exhibited acceptable thermal shock resistance as the specimens sustain up to 298 and 325 thermal cycles respectively. The microstructural analysis suggested against the formation of any major deformity or structural changes at the higher temperature as investigated by thermal shock experiment.

Protection offered by thermal barrier coatings to Al-Si alloys at high temperatures – A microstructural investigation

Abstract Thermal barrier coatings, with ∼50 µm thick Nickel-Aluminide bond coat and ∼250 µm thick Yttria-Stabilized zirconia ceramic top coats were synthesized by Air Plasma Spray coating process on flat plates machined from Al-11Si alloy diesel engine pistons. Coating process parameters and qualifications that were followed were based on previous studies made on the same substrates. The ceramic coatings were subjected to various thermal treatments such as (a) thermal shock cycling tests and (b) continuous heating in a furnace. Uncoated Al-Si samples were simultaneously subjected to the same thermal treatments and used as reference to study the protection offered by the coatings to the base metal substrates. Thermal shock cycles tests involved subjecting the coated and uncoated Al-Si plates to oxy-acetylene flame to allow the ceramic surface to be maintained at 500 °C for 1000 cycles (one cycle comprised of heating for 60 s, withdrawal from flame and forced cooling in ambient air for 60 s) and similar thermal shock cycles in an electric furnace. The specimen were also heated in a furnace at 300 °C for 1000 continuous hours. Stresses induced during thermal shock cycles and oxidation of bond coat-ceramic coat interface during the exposure to heat are the main reasons for the coating’s failure. Details of an investigation on the microstructural changes and oxidation behaviour of the substrate and the ability of the coatings to protect the metal substrates from oxidation are presented. Microstructural studies were carried out by employing a Scanning Electron Microscope attached with Energy Dispersive X-ray spectroscopy facility. The findings were compared on (a) uncoated Al-Si alloy and (b) thermal barrier coated Al-Si alloy with a goal to understand the capability of the coatings to protect the metal from the influences of thermal treatments, at temperatures lower than the melting point of the Al-Si alloy.

Effectiveness estimation of turbo-compound scheme application on purpose of indicators increasing of aircraft piston diesel engine of 300 h.p

Effectiveness estimation of turbo-compound scheme application on purpose of indicators increasing of aircraft piston diesel engine of 300 h.p

Energetic Analysis of the Aircraft Diesel Engine

The analysis of the distribution of thermal energy generated during the combustion process in internal combustion engines and the estimation of individual losses are important regarding performance and efficiency. The article analyses the energy balance of the designed two-stroke opposed piston diesel engines with offset, i.e. the angle by which the crankshaft at the side of exhaust ports is ahead of the crankshaft at the side of intake ports. Based on the developed zero-dimensional engine model, a series of simulations were performed in steady-state conditions using the AVL BOOST software. The values of individual energy losses, including cooling losses, exhaust gas losses, friction losses were obtained. The influence of decreasing and increasing the offset on the performance of the tested engine was analysed.

Investigations on ablation for highly-intensified diesel engine piston material

With the improvement of the degree of diesel engine enhancement, the thermal load of the piston is greatly increased, and higher requirements is imposed on the ablation resistance of the piston material. Three kind of piston materials were selected and the ablation performance was analyzed through experiments and simulation calculations, then the ablation mechanism and ablation model of piston materials were analyzed. Results revealed that Ablation mechanisms of piston material are melting ablation and gas flow erosion. Al-Si alloy materials have poor anti-ablative properties. Al2O3 f/Al-Si composites and aluminum borate whisker reinforced Al-Si matrix composites exhibited higher anti-ablation properties, which contributed by the dense structure and high yield strength at high temperature of the composites. Aluminum borate whisker reinforced Al-Si matrix composites has the best anti-ablative properties.

Thermal Analysis of a Zirconium Dioxide Coated Aluminum Alloy Piston

Performance and operating costs are the most important factors in internal combustion engines. It is one of the most commonly used methods to coat pistons with advanced technological ceramic materials in order to improve performance and fatigue life in internal combustion engines. In this study, changes in temperature and heat flux were investigated in various thickness coatings made on a 2500 cc turbo diesel engine piston. As bonding coat, NiCrAl was used in a thickness of 0.2 mm, while ZrO2 (zirconium dioxide) was used in thicknesses of 0.2-0.4-0.6 and 0.8 mm as thermal barrier coating material. The piston was modeled in PTC Creo parametric software and then transferred to ANSYS Workbench environment to create a mathematical model. Engineering calculations were also done using the finite element method. After the calculation, the temperatures at the depth of 5 mm from the combustion chamber upper surface, the binder layer upper surface, the thermal coating upper surface and the combustion chamber upper surface were compared. As a result, it was observed that the combustion chamber and the section at the depth of 5 mm from the combustion chamber had a temperature decrease of 13%.

Design, Optimization and Analysis of a 4-stroke Diesel Engine Piston and Piston rings using Different Materials

Modern Automobiles expect a high performance from its engines, which in turn places its requirements on the piston and cylinder components. Hence the piston has to deal with harsher, and tougher thermal and mechanical conditions. It has to undergo higher operating temperatures and pressures as well as higher speeds and at the same time keeping a check on the emissions. Pistons play a key role in increasing engine efficiency by reducing weight and frictional losses. This has made it essential to devise and search unique and creative concepts and materials for Pistons repeatedly, which offers what the engine demands.In this work Aluminium Alloy-4032 has been selected as the piston material of a 4-Stroke Diesel Engine and the piston rings are made of grey cast iron and alloy steel. Piston is designed by analytical methods taking both thermal and structural effects into consideration, then modelled on CATIA V5 and the analysis of structural deformation due to thermal stresses has been done using Finite Element Analysis of Steady State Thermal and its effect on static structure using Analysis software ANSYS.

Thermal analysis of carbon-carbon piston for commercial vehicle diesel engine using CAE tool

ABSTRACT Experimental studies indicate that the maximum stress acted on the top portion of the piston and stress concentration is also the main cause of fatigue failure. This article discusses the improvement on the piston to endure high structural and thermal stresses and to moderate stress concentration the top portion of the piston. An aluminum alloy piston can be replaced by a carbon-carbon piston which has low thermal stress in same working condition. In this paper, thermal analysis of carbon-carbon composite material on commercial vehicle diesel engine piston was studied and the results were compared with aluminum alloy piston for maximum stress.

High-strength Pistons for Diesel Engines

High-strength Pistons for Diesel Engines

ОПТИМИЗАЦИЯ УГАРА МОТОРНОГО МАСЛА В СУДОВОМ ДИЗЕЛЕ С ВЫСОКИМ НАДДУВОМ ПО КРИТЕРИЮ ИЗНАШИВАНИЯ

The results of modeling the impact of oil burning on the condition of the ship forced trunk piston diesel engine when using lubricants with different operating properties. The dependence of wear rate on oil fume, the quality of used lubricants and marine diesel forcing is obtained by modeling wear using the theory of planning experiments. The area of minimal wear has been determined. There has been detected the most efficient waste oil providing favorable conditions for resource-saving operation of the internal combustion engine. It is inferred that reduction of engine oil fume changes the main parameters of its aging. At the same time, the intensity of oil aging in main directions and of engine wear reduce from 0.75 to 2.25 g/(kW∙h), whereas the fume increases. Its further increase is accompanied by an increase in the rate of oil aging and engine wear. The detected "fracture" depending on И( g y) after passing the border g yopt = 2.25-2.5 g/(kW∙h) is stipulated by different ratio of oil exchange in the lubrication system and the ingress of gases into the crankcase. There has been determined the degree of oil burning, at which sludging and lacquer formation of the internal combustion engine is least intense. The smallest carbon deposits on pistons and in the crankcase of the engine can be observed when the diesel engine is operating in the zone of optimal carbonation. Experimentally, the dependence of tribotechnical properties, in particular, wear of insoluble products of oil aging has been detected at different degrees of oil burning. It is revealed that these characteristics also depend on the quality of the used fuels and lubricants and the conditions of formation and turnover of the oil film on the mirror of the cylinder, the thermal effect on it of the engine workflow. The result of simulation is the prediction of resource-saving operation of marine trunk diesel engines by maintaining oil fume at the optimal level.

Design, Optimization and Analysis of a 4-stroke Diesel Engine Piston and Piston rings using Different Materials

Modern Automobiles expect a high performance from its engines, which in turn places its requirements on the piston and cylinder components. Hence the piston has to deal with harsher, and tougher thermal and mechanical conditions. It has to undergo higher operating temperatures and pressures as well as higher speeds and at the same time keeping a check on the emissions. Pistons play a key role in increasing engine efficiency by reducing weight and frictional losses. This has made it essential to devise and search unique and creative concepts and materials for Pistons repeatedly, which offers what the engine demands. In this work Aluminium Alloy-4032 has been selected as the piston material of a 4-Stroke Diesel Engine and the piston rings are made of grey cast iron and alloy steel. Piston is designed by analytical methods taking both thermal and structural effects into consideration, then modelled on CATIA V5 and the analysis of structural deformation due to thermal stresses has been done using Finite Element Analysis of Steady State Thermal and its effect on static structure using Analysis software ANSYS

Fretting fatigue optimization of piston skirt top surface of marine diesel engine

Composite pistons are often used in highly rated marine diesel engines. Fretting usually occurs on the mating surfaces of piston crown and skirt due to alternating loads. A finite element contact model is introduced to calculate the temperature and stress distribution in the composite piston of a marine diesel engine. The Archard model and Smith–Watson–Topper parameter (a prediction parameter of fretting fatigue, also called SWT parameter for short), which is used as fretting wear and fatigue criteria, are calculated according to the stress and strain variation and relative slip on the contact surface. The model has been validated by previous cylindrical–flat contact experiments. The effects of shape of contact face and pretension of bolts on fretting performance have been analyzed. To reduce the possibility of fretting failure of the composite piston, the expression of the generating line of the piston skirt contact surface has been designed by Theory of elasticity. The parameters of the generating line have been optimized with nonlinear sequential quadratic programming and finite element mesh updating method. The optimization results show that the fretting fatigue parameter SWT on the optimized contact surface can be reduced by more than 35.6%, which means the longer fatigue life of the pistons. Some suggestions for designing contact surfaces have also been proposed. In the end, the design was proved by durability tests of the engine.

Microscopical Characterization of Cast Hypereutectic Al-Si Alloys Reinforced with Graphene Nanosheets

This paper illustrates the effects of stirring and graphene nanosheet (GNS) addition on the microstructure and mechanical behaviour of 393 hypereutectic Al-Si alloys used in the diesel engine pistons. Two processing routes were applied to fabricate hypereutectic Al-Si alloys: The first route mainly depends on stirring Al-Si alloys for 12 minutes at 400 rpm. The second one involves stirring Al-Si alloys for 2 minutes and then adding graphene nanosheets into the vortex, and consequently continue stirring for 10 minutes at 400 rpm. Results show that the distribution of the primary silicon was improved significantly in stir casting at both the edge and the center of the samples with relative reduction of 34% and 37% in the average particle size respectively. This average primary silicon size was further reduced by 17% with the addition of 1 wt% GNSs. GNS embedding into Al-Si alloy matrix resulted in remarkable increase in hardness values of the nanocomposites compared to the cast alloy.

Microstructural Analysis and Transport Properties of Thermally Sprayed Multiple-Layer Ceramic Coatings

Multilayer, graded ceramic/metal coatings were prepared by an air plasma spray method on Ti-6Al-4V, 4140 steel and graphite substrates. The coatings were designed to provide thermal barriers for diesel engine pistons to operate at higher temperatures with improved thermal efficiency and cleaner emissions. A systematic, progressive variation in the mixture of yttria-stabilized zirconia and bondcoat alloys (NiCoCrAlYHfSi) was designed to provide better thermal expansion match with the substrate and to improve thermal shock resistance and cycle life. Heat transfer through the layers was evaluated by a flash diffusivity technique based on a model of one-dimensional heat flow. The aging effect of the as-sprayed coatings was captured during diffusivity measurements, which included one heating and cooling cycle. The hysteresis of thermal diffusivity due to aging was not observed after 100-h annealing at 800 °C. The measurements of coatings on substrate and freestanding coatings allowed the influence of interface resistance to be evaluated. The microstructure of the multilayer coating was examined using scanning electron microscope and electron probe microanalysis.

Design and Analysis of a Heavy-Duty Diesel Engine Piston

Design and Analysis of a Heavy-Duty Diesel Engine Piston

Thermal analysis of Cr2O3 coated diesel engine piston using FEA

Powder metallurgy is one of the effective composite processing techniques in recent years. For production of hybrid nano composites powder metallurgy is one of the effective technique that gives the proper understanding of role of reinforcement, effect of grain size and compaction capability of the metal matrix nano composites. When it is more effective by addition of two or more different reinforcing materials in it. To understand the particle distribution, volume fraction, grain size, porosity, density of metal matrix composites it is necessary to undergo characterization. Metal matrix nano composite are very attractive for automotive, aerospace, military and tribological applications. This article is an attempt to understand the process of powder metallurgy and its effect on different properties of composites.

Quasi-dynamic and thermal analysis of a diesel engine piston under variable compression

Due to ever increasing demand for high speeds of automobiles and high gas loads, the piston of an IC engine is subjected to large thermal and structural stresses. The authors have therefore embarked upon evaluating the stresses induced in the piston and also study the effect of compression ratio on it. An experimental setup consisting of a computerized variable compression ratio diesel engine test rig with necessary instrumentation was established. A comprehensive load history in terms of pressure vs. crank angle(p-Θ) diagram and (pressure vs. gas volume), speed, fuel and air consumption rates, turning moment etc., were obtained at compression ratios of 16.5,17.5 and 18.5 from the experimentation. Part one is heat transfer analysis for evaluating the thermal boundary conditions like heat transfer coefficients and heat flux. Further the mean temperature of the working fluid is also obtained from thermodynamic analysis. Part two is dynamic analysis by using the equations of equilibrium for slider-crank mechanism. Part three is stress analysis using finite element method coupled field at critical angles of crank rotation where either inertia forces or wrist pin forces are maximum. The results in the form of von-mises stresses and deformation are presented. Further, factor of safety is evaluated. It was observed that increasing compression ratio has an appreciable effect on the stresses. It was interestingly observed that the mean temperature of gases is higher at compression ratio of 17.5. Stresses developed due to differential thermal expansion in the piston form a significant part of the total stresses.

Chemical Reaction Processes of Fuel Reformation by Diesel Engine Piston Compression of Rich Homogeneous Air-Fuel Mixture

<div class="section abstract"><div class="htmlview paragraph">To extend the operational range of premixed diesel combustion, fuel reformation by piston induced compression of rich homogeneous air-fuel mixtures was conducted in this study. Reformed gas compositions and chemical processes were first simulated with the chemistry dynamics simulation, CHEMKIN Pro, by changing the intake oxygen content, intake air temperature, and compression ratio. A single cylinder diesel engine was utilized to verify the simulation results. With the simulation and experiments, the characteristics of the reformed gas with respect to the reformer cylinder operating condition were obtained. Further, the thermal decomposition and partial oxidation reaction mechanisms of the fuel in extremely low oxygen concentrations were obtained with the characteristics of the gas production at the various reaction temperatures.</div><div class="htmlview paragraph">The main reformed products were hydrogen (H<sub>2</sub>), carbon monoxide (CO), carbon dioxide (CO<sub>2</sub>), methane (CH<sub>4</sub>), and ethylene (C<sub>2</sub>H<sub>4</sub>) and the results indicated that the reforming depends on the maximum temperature in the cylinder, however, the amount of reformed gas is lower than the values predicted by the CHEMKIN simulation.</div></div>