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Journal Article

Finite Element Thermo-Structural Methodology for Investigating Diesel Engine Pistons with Thermal Barrier Coating

2018-12-14
Abstract Traditionally, in combustion engine applications, metallic materials have been widely employed due to their properties: castability and machinability with accurate dimensional tolerances, good mechanical strength even at high temperatures, wear resistance, and affordable price. However, the high thermal conductivity of metallic materials is responsible for consistent losses of thermal energy and has a strong influence on pollutant emission. A possible approach for reducing the thermal exchange requires the use of thermal barrier coating (TBC) made by materials with low thermal conductivity and good thermo-mechanical strength. In this work, the effects of a ceramic coating for thermal insulation of the piston crown of a car diesel engine are investigated through a numerical methodology based on finite element analysis. The study is developed by considering firstly a thermal analysis and then a thermo-structural analysis of the component.
Journal Article

1D Numerical and Experimental Investigations of an Ultralean Pre-Chamber Engine

2019-11-19
Abstract In recent years, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations. With this solution, in fact, it is possible to simultaneously reduce NOx raw emissions and fuel consumption due to decreased heat losses, higher thermodynamic efficiency, and enhanced knock resistance. However, the real applicability of this technique is strongly limited by the increase in cyclic variation and the occurrence of misfire, which are typical for the combustion of homogeneous lean air/fuel mixtures. The employment of a Pre-Chamber (PC), in which the combustion begins before proceeding in the main combustion chamber, has already shown the capability of significantly extending the lean-burn limit. In this work, the potential of an ultralean PC SI engine for a decisive improvement of the thermal efficiency is presented by means of numerical and experimental analyses.
Journal Article

An Investigation of the Effects of the Piston Bowl Geometries of a Heavy-Duty Engine on Performance and Emissions Using Direct Dual Fuel Stratification Strategy, and Proposing Two New Piston Profiles

2020-03-16
Abstract Direct dual fuel stratification (DDFS) strategy benefits the advantages of the RCCI and PPC strategies simultaneously. DDFS has improved control over the heat release rate, by injecting a considerable amount of fuel near TDC, compared to RCCI. In addition, the third injection (near TDC) is diffusion-limited. Consequently, piston bowl geometry directly affects the formation of emissions. The modified piston geometry was developed and optimized for RCCI by previous scholars. Since all DDFS experimental tests were performed with the modified piston profile, the other piston profiles need to be investigated for this strategy. In this article, first, a comparative study between the three conventional piston profiles, including the modified, stock, and scaled pistons, was performed. Afterward, the gasoline injector position was shifted to the head cylinder center for the stock piston. NOX emissions were improved; however, soot was increased slightly.
Journal Article

Effects of Stepped-Lip Combustion System Design and Operating Parameters on Turbulent Flow Evolution in a Diesel Engine

2020-01-16
Abstract Interactions between fuel sprays and stepped-lip diesel piston bowls can produce turbulent flow structures that improve efficiency and emissions, but the underlying mechanisms are not well understood. Recent experimental and simulation efforts provide evidence that increased efficiency and reduced smoke emissions coincide with the formation of long-lived, energetic vortices during the mixing-controlled portion of the combustion event. These vortices are believed to promote fuel-air mixing, increase heat-release rates, and improve air utilization, but they become weaker as main injection timing is advanced nearer to the top dead center (TDC). Further efficiency and emissions benefits may be realized if vortex formation can be strengthened for near-TDC injections. This work presents a simulation-based analysis of turbulent flow evolution within a stepped-lip combustion chamber.
Journal Article

A Non-Linear Finite Element Approach Applied to Diesel Piston Combustion Bowl Rim Strength Assessment

2013-04-08
2013-01-0293
The single piece aluminium alloy piston remains the dominant and preferred design offering for highly loaded diesel engines. Piston manufacturers have progressively developed aluminium alloys, machining capability, and design geometries to cope with increasing thermal and mechanical loading. In conjunction with these developments, the methodology used to analyse the pistons has also improved as software and digital computers have advanced. This advancement has permitted larger more detailed models and more sophisticated simulation of the material behaviour, in response to the loading and contact conditions applied to pistons. Transient finite element analysis was first applied to diesel pistons in the late 1970's using a linear elastic approach, coupled with a life assessment based on limited low cycle fatigue data. This methodology gave valuable insights into the mechanism of piston failures, particularly at the combustion bowl rim of diesel pistons.
Technical Paper

Topology Optimisation of Brake Caliper

2020-10-05
2020-01-1620
The objective of the research is to develop a lightweight yet stiff, 2 piston fixed brake caliper which can be used in formula student race car. To make a race car, its components need to be lighter. To stop a car with minimum stopping distance, it needs to have a sophisticated braking system with well-designed components. The designing of the caliper is carried out on the Altair Inspire software. The topology optimisation algorithm is used to minimise the weight of the caliper without compromising the stiffness. The structural analysis is also carried out on the Altair Inspire. The caliper is also tested for fatigue failure using Ansys.
Technical Paper

Correlation of Experimental Thermal Mapping and FEA Thermal Simulation for Cylinder Head for Diesel Engine Development

2020-09-25
2020-28-0353
For upgrading/new engine development, the piston and cylinder head are the most exposed members due to amplified mechanical and thermal loadings. Mechanical loading is basically due to the combustion gas pressure in the combustion chamber and its scale can be judged in terms of peak cylinder pressure. Thermal loading is due to temperature by heat flux acting on the piston surface, cylinder liner and the cylinder head. The importance of the various loads applied on the head and cylinder block in operation was assessed and a method of predicting their influence on the structural integrity of the components described by doing actual test on engine test bench. Therefore, it’s very important to have thermal survey of the engine. The engine thermal survey test was primarily developed to measure the temperature in the head of the engine to determine if the temperatures that are measured are within the design guidelines for appropriate engine operation.
Technical Paper

Modeling and Simulation of Automotive AC Components (Condenser & Piston) with Experimental Validation

2020-09-25
2020-28-0357
Automotive Air Conditioning is the process of removing the heat and moisture from the interior of an occupied space to improve comfort of occupants. A condenser is a device or unit used to condense refrigerant from its gaseous to its liquid state, by cooling it. In so doing, the latent heat is given up by the substance and transferred to the surrounding environment. It is made of Aluminum Alloy Material and subjected to very high internal stresses due to refrigerant pressure, thermal / inertia and dynamic load. In order to evaluate the structural integrity of the condenser assembly under these loading conditions, operating frequency should be far away from the resonance frequency and component design should be robust to sustain external excitation load coming from the engine & road. The above design evaluation criteria is also applicable for piston of AC’s reciprocating compressor.
Technical Paper

Assessment of the Metallurgical and Mechanical Properties of Stir cum Squeeze Cast A356 with 5wt. % SiC and x wt. % Flyash Hybrid Composites

2020-09-25
2020-28-0397
The forged connecting rod and pin experience a large amount of stresses due to cyclic load for a long period of time induced by the reciprocating movement of the piston. The proposed work focused to produce lightweight composites with high strength using waste flyash and simple manufacturing process. In this context, the proposed experimental work was formulated to develop aluminium alloy hybrid metal matrix composite of A356 alloy with silicon carbide and flyash processed through stir cum squeeze casting process under optimal parametric condition. The samples were subjected to varying flyash content of 0, 5, 10wt.% and SiC of 5wt.% kept constant. Responses like metallography, hardness, impact strength, flexural strength, fatigue strength were observed for the manufactured hybrid composites. There was a significant improvement in the properties with a higher weight percentage addition of 10wt.% flyash and 5wt.% SiC with A356 hybrid composites.
Technical Paper

Design and Couple Field Analysis of Uncoated and Coated Aluminium Metal Matrix Hybrid Composite Piston

2020-09-25
2020-28-0391
Piston is the most imperative part of an automotive engine in which it exchanges drive due to expanding gas in the cylinder to the crankshaft through the piston rod. During the combustion of fuel charge inside the ignition chamber, high pressure and temperature are developed and the piston is imperiled to high mechanical and thermal stresses. The main objective of the proposed work is to analyse the stress distributions and thermal behaviour of uncoated A356 with 5wt% SiC and 10wt% Fly Ash HMMC piston crown and Plasma sprayed Yttrium Stabilized Zirconia (Y-PSZ) coated A356 with 5wt% SiC and 10wt% Fly Ash HMMC piston crown. A356 with 5wt% SiC and 10wt% Fly Ash HMMC were fabricated via squeeze casting to improve the performance of a petrol engine. A structural model of an HMMC piston crown was made using CREO software and structural and thermal analysis was done using ANSYS. Further coupled field analysis is done to find the stress and temperature distribution on the piston.
Technical Paper

Heat Flux between Impinged Diesel Spray and Flat Wall

1991-11-01
912460
In a high-speed DI diesel engine, fuel sprays impinge surely on a wall of a piston cavity. Then the phenomenon of the heat transfer between the impinged spray and the wall appears and it has the strong effect on the combustion processes of the engine. The purpose of this study are to clarify basically the heat transfer characteristics. In the experiments, the fuel was injected into the quiescent inert atmosphere with a high temperature under high pressure field, and an evaporative single diesel spray was impinging upon a flat wall. And, the temperature distribution on the wall surface in a radial direction was detected by the Loex-Constantan thin film thermo-couples. Thus, the heat flux between the impinged spray and the wall surface was calculated from the temperature profile within the wall by Fourier's equation using the finite difference method, under the assumption of the one-dimensional heat conduction.
Technical Paper

A Visualized Study for the Effect of Swirl Strength on SI Engine Combustion Characteristics

1991-11-01
912455
Tests were performed in an actual engine with swirl and without to understand charge swirl effect for an 1.5l, 4-cyl and 4-stroke SI engine. Swirling inlet flow resulted in the improvement of the engine performance at engine speed of up to 4,000rpm, however, it was reversed at higher engine speed, compared with that of ordinary non-swirling case. Additionally, a single shot visualized engine driven by a rapid compression expansion machine was built separately to inspect the swirl effect on combustion process. In the visualization study, stoichiometric LPG -air mixture was used at three different levels of swirl strength, where the equivalent engine speed was set at 1500, 2500 and 3500 rpm and taken by shadowgraph technique with a high speed camera. A visualized tests supported the combustion rate increasing phenomena excited by swirl by observations on equivalent flame radii and, also, by energy release fractions and cyclic variations.
Technical Paper

A 400HP Truck Engine Operating on Natural Gas

1991-11-01
912476
A 14 litre turbo charged intercooled diesel engine has been re-engineered to operate as a spark ignition engine fuelled with natural gas. The design targets were for an efficient engine with low emissions using the lean burn capability of natural gas but without sacrificing power output. The resulting ultra lean burn spark ignition engine achieves diesel engine thermal efficiency, with a much reduced NOx emissions though higher NMHC emissions. The engine changes included revised compression ratio, and combustion chamber shape, inlet system modifications to increase turbulence during combustion, i.e., a “smart burn” system, and a new engine management strategy using a “drive by wire” computer control of fuel and throttle and spark timing. The engine has begun duty in an articulated truck in a short haul parts delivery operation, and monitoring of the in service performance has begun.
Technical Paper

The STM4 - 120RH and STM4 - 120DH Stirling Engines Performance Comparison

1991-11-01
912478
Stirling Thermal Motors, Inc., (STM) of Ann Arbor, Michigan, has been developing a general purpose Stirling engine designated the STM4-120.* The configuration of the STM4-120 was based on the Ford/Philips automotive Stirling engine which was successfully demonstrated in a 4500 pound Ford Torino in 1976. This engine, designated the 4-215, was a four-cycle, double-acting engine with a fixed angle swashplate drive and produced 175 horsepower (128 kW). During the Ford program, three obstacles to mass production were identified: the complexity of the mean pressure power control, the life and reliability of the rod seals, and the complex geometry and manufacturability of the heater heads. In the conceptual design phase of the STM4-120, effort was concentrated on addressing and overcoming these obstacles.
Technical Paper

A Temperature Controller for Glow Plugs and its Usage in an Engine

1991-11-01
912510
Increased power outputs in high performance diesel engines are being obtained by the use of increased boost pressures obtained from the engine's turbochargers. Reduced compression ratio because of high boost tends to cause cold starting problems and white smoke at idle and light load, especially with a cold engine. One method of alleviating these problems is to make use of glow plugs in the engine cylinders. Applications of glow plugs include a glow plug ignited natural gas engine, methanol DI engine, and IDI and DI diesel engines. This paper describes a glow plug control system that actually controls the glow plug temperature directly. This new control system is better than the systems currently fitted to IDI diesel vehicles. The glow plug controller maintains a constant temperature at the glow plug without the use of any sensor external to the glow plug.
Technical Paper

Heat Transfer Studies in an Adiabatic Diesel Engine

1991-11-01
912502
Numerical calculation based on finite element method are carried out to calculate the temperature field in an adiabatic diesel engine piston having diameter. 127 mm and made of aluminum alloy. The engine cylinder wall have the coated externally by a thin layer of very high grade ceramic insulating material. The isothermic distribution in the piston body and the heat flow rates to the cooling media at different loads have been depicted for both cases with and without insulation coating. The paper first reviews the current state of development of ‘adiabatic’ diesel engine in Europe, U.S.A and the Japan. This review section is followed by a brief description of the common element of hostile features, then comes the experimental program on thermally insulated components for single cylinder engine in the research center of Tabriz and finally by a theoretical section dealing with the performance potential of composed engine schemes based on ‘adiabatic’ engine operation.
Technical Paper

An Analytical Solution for Spherical Joint Mechanism Including Coulomb Friction

1991-11-01
912499
This paper introduces the friction sphere concepts to consider the effects of friction in the spherical joint and presents a new effective numerical solution method for the analysis of multibody systems with spherical joint under Coulomb friction. Complete equations of motion and reaction forces are derived for dynamic analysis of multibody systems by using Lagrangian formulation. The numerical solutions of the new method are illustrated by its applications to the variable displacement car air conditioning compressor, which has five pistons connected to the wobble plate by five actuating rods with spherical joints at both ends. The new method successively accomplishes the solutions of the equations of motion and reaction forces of the compressor in less computing time than the conventional method.
Technical Paper

Natural Gas for Vehicles (NGV)

1991-11-01
912558
The NGV industry in Australia is developing and has as its objective heavy vehicle fuel replacement. Security of fuel supply and national economic benefits have caused the Government to encourage the use of alternative fuels, such as NGV. Significant progress has been achieved in the development of vehicle conversion technology, refuelling stations and marketing plans. Demonstration activities of 3 different vehicles types have proved the economic viability for the fleet operator. The progress toward fleet usage of NGV is encouraging and a summary of market penetration in various sectors is provided.
Technical Paper

A Study on Performance Improvement of Natural Gas Engine

1991-11-01
912559
Natural gas possesses several characteristics that make it desirable as an engine fuel; 1)lower production cost, 2)abundant commodity and 3)leaner energy source than gasoline. Due to the physical characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of 10-20% when compared to a normal gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of compression ratio, air/fuel ratio, spark advance and supercharging. It emphasizes how to improve the power characteristics of a natural gas engine. Combustion characteristics are also studied using an ion probe. The ion probe is applied to measure flame speed of gasoline and methane fuels.
Technical Paper

Purification Characteristics of Catalytic Converters for Natural Gas Fueled Automotive Engine

1991-11-01
912599
The purification performances of some kinds of catalytic converters ( Pt, Rh, Pd, Pd/Rh, Pd/Pt, Pt/Rh/Pd, Pt_Pd and Pd_Cu) were investigated to select suitable catalytic converters for natural gas fueled automotive engines. Pd series catalysts showed better performance among the noble metal catalysts for oxidation of unburned methane in exhaust gas. The optimum loading of Pd catalyst is the range of 1.6 to 3.2 g/L. The dual-bed catalyst, Pt_Pd, consisting of a Pt catalyst in the front and a Pd catalyst in the rear, showed a performance better than Pd series catalysts. When aged to an accumulated running distance of 50000 miles, the catalytic activity of the Rh catalysts is much reduced, but those of Pd and Pt catalyst are affected little by aging. The aged Pd/Rh catalyst showed superior emissions' purification performance at the stoichiometric condition, but poor at lean mixture conditions.
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