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Technical Paper

3D Modeling Applied to the Development of a DI Diesel Engine: Effect of Piston Bowl Shape

1997-05-01
971599
Multidimensional computations are carried out to aid in the development of a direct injection Diesel engine. Intake, compression, injection and combustion processes are calculated for a turbo-charged direct injection Diesel engine with a single intake valve. The effects of engine speed and engine load, as well as the influence of exhaust gas recirculation are compared to experimental measurements. The influence of piston bowl shape is investigated. Three dimensional calculations are performed using a mesh built from the complete CAD definition of the engine, intake port, cylinder and piston bowl. The injection characteristics are found to be of primary importance in the control of the combustion process. At a given injection set, piston bowl shape can be optimized for fluid dynamic and combustion.
Technical Paper

3D Vortex Simulation of Intake Flow in a Port-Cylinder with a Valve Seat and a Moving Piston

1996-05-01
961195
A Lagrangian random vortex-boundary element method has been developed for the simulation of unsteady incompressible flow inside three-dimensional domains with time-dependent boundaries, similar to IC engines. The solution method is entirely grid-free in the fluid domain and eliminates the difficult task of volumetric meshing of the complex engine geometry. Furthermore, due to the Lagrangian evaluation of the convective processes, numerical viscosity is virtually removed; thus permitting the direct simulation of flow at high Reynolds numbers. In this paper, a brief description of the numerical methodology is given, followed by an example of induction flow in an off-centered port-cylinder assembly with a harmonically driven piston and a valve seat situated directly below the port. The predicted flow is shown to resemble the flow visualization results of a laboratory experiment, despite the crude approximation used to represent the geometry.
Technical Paper

3d-Elastohydrodynamic Simulation Model for Structure-Borne Noise Analyses of a DI Diesel Engine

2016-06-15
2016-01-1854
The present article is concerned with the investigation of the engine noise induced by the piston slap of an actual passenger car Diesel engine. The focus is put on the coherence of piston secondary movement, impact of the piston on the cylinder liner, generated structure-borne noise excitation of the engine structure and the occurring acceleration on the engine surface. Additionally, the influence of a varying piston-pin offset and piston clearance is evaluated. The analyses are conducted using an elastohydrodynamic multi-body simulation model, taking into account geometry, stiffness and mass information of the single components as well as considering elastic and hydrodynamic behavior of the piston-liner contact. A detailed description of the simulation model will be introduced in the article. The obtained results illustrate the piston secondary motion and the related structure-borne noise on the engine surface for several piston-pin offsets and piston clearances.
Journal Article

4 L Light Duty LPG Engine Evaluated for Heavy Duty Application

2010-05-05
2010-01-1463
Many applications of liquefied petroleum gas (LPG) to commercial vehicles have used their corresponding diesel engine counterparts for their basic architecture. Here a review is made of the application to commercial vehicle operation of a robust 4 L, light-duty, 6-cylinder in-line engine produced by Ford Australia on a unique long-term production line. Since 2000 it has had a dedicated LPG pick-up truck and cab-chassis variant. A sequence of research programs has focused on optimizing this engine for low carbon dioxide (CO₂) emissions. Best results (from steady state engine maps) suggest reductions in CO₂ emissions of over 30% are possible in New European Drive Cycle (NEDC) light-duty tests compared with the base gasoline engine counterpart. This has been achieved through increasing compression ratio to 12, running lean burn (to λ = 1.6) and careful study (through CFD and bench tests) of the injected LPG-air mixing system.
Technical Paper

50cc Two-Stroke Engines for Mopeds, Chainsaws and Motorcycles with Catalysts

1990-09-01
901598
4 different engine concepts with Catalyst have been developed in regard to pollutant emission, fuel efficiency and performance. Despite the wide power range from 1,2 HP to 12 HP and the different applications of these engines to Mopeds, Chainsaws and Motorcycles, the problems to solve have been similar. Internal measures such as optimized carburetion, cooling, piston shape and clearance, scavenging and tuning of the exhaust must enable the engine to run on the lean side. This is imperative to supply sufficient oxygen for the exothermal reaction and to keep the energy to be converted in the Oxidation Catalyst at a minimum. Secondary measures have been taken to shorten the Catalyst's light-off and to keep the temperature range in limits.
Technical Paper

59 The Rotating Cylinder Valve 4-Stroke Engine A Practical Alternative

2002-10-29
2002-32-1828
The Rotating Cylinder Valve (RCV) Engine is a novel 4 cycle engine that is a practical alternative to conventional 2 and 4 stroke designs, in particular for small capacity single cylinder applications. It is primarily intended to address applications where emissions legislation is forcing manufacturers to abandon the traditional carburetted 2 stroke. It has particular benefits for the moped/light motorcycle market. The engine operates on a simple principle. The cylinder liner is rotated around the piston at half engine speed via a pair of bevel gears. A port in the side of this cylinder indexes with inlet and exhaust ports in the surrounding casing. This rotary valve serves the cylinder as the engine cycles through the conventional 4 stroke cycle. The main technical issue that has been addressed is the design of a practical rotary valve seal.
Technical Paper

71 Scavenging system layout of a 25 cc two-stroke engine intended for stratified scavenging

2002-10-29
2002-32-1840
A sequentially stratified scavenged engine is characterised by the principle that the cylinder is first scavenged by pure air, followed by the air/fuel mixture. The air is introduced into the upper part of the scavenging ducts through a piston port or a reed valve. To take full advantage of the stratified scavenged principle, the scavenging ducts have to be designed in a way, so that they can accommodate all the air that is delivered into the scavenging ducts. When converting a conventional two-stroke engine into a stratified scavenging engine, it is also important that the tuning and basic scavenging characteristics of the standard engine are not deteriorated. In this paper it is shown how these two aspects can be combined. Together with a theoretical approach for dimensioning the volume and length of the scavenging ducts, it gives a guideline on how to design the basic engine layout, for a stratified scavenged two-stroke engine.
Technical Paper

A 3D-CFD Methodology for Combustion Modeling in Active Prechamber SI Engines Operating with Natural Gas

2022-03-29
2022-01-0470
Active prechamber combustion systems for SI engines represent a feasible and effective solution in reducing fuel consumption and pollutant emissions for both marine and ground heavy-duty engines. However, reliable and low-cost numerical approaches need to be developed to support and speed-up their industrial design considering their geometry complexity and the involved multiple flow length scales. This work presents a CFD methodology based on the RANS approach for the simulation of active prechamber spark-ignition engines. To reduce the computational time, the gas exchange process is computed only in the prechamber region to correctly describe the flow and mixture distributions, while the whole cylinder geometry is considered only for the power-cycle (compression, combustion and expansion). Outside the prechamber the in-cylinder flow field at IVC is estimated from the measured swirl ratio.
Technical Paper

A 3D-Simulation with Detailed Chemical Kinetics of Combustion and Quenching in an HCCI Engine

2008-06-23
2008-01-1655
A 3D-CFD model with detailed chemical kinetics was developed to investigate the combustion characteristics of HCCI engines, especially those fueled with hydrogen and n-heptane. The effects of changes in some of the key important variables that included compression ratio and chamber surface temperature on the combustion processes were investigated. Particular attention was given, while using a finer 3-D mesh, to the development of combustion within the chamber crevices between the piston top-land and cylinder wall. It is shown that changes in the combustion chamber wall surface temperature values influence greatly the autoignition timing and location of its first occurrence within the chamber. With high chamber wall temperatures, autoignition takes place first at regions near the cylinder wall while with low surface temperatures; autoignition takes place closer to the central region of the mixture charge.
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

A 7 -Cylinder IVD Compressor for Automotive Air Conditioning

1989-02-01
890309
A 7-cylinder, wobble plate type, infinitely variable displacement, (IVD), compressor has been developed to meet the following requirements as set forth by the world automotive manufacturers: 1 Wide range of capacity control to eliminate clutch cycling which causes temperature and humidity fluctuations of louver outlet air and unexpected engine load variations 2 Near perfect protection of the evaporator against icing 3 Reliability under all field operating conditions 4 Quiet operation in a compact and lightweight package to suit the new trends in automotive design. A simpler mechanism has been applied to the variable angle cam drive and wobble plate rotation prevention method than with the conventional IVD compressor. The 7-cylinder design, with fewer parts for the piston drive mechanism, enables a quiet compressor of 161.3 cc displacement in a 118 mm diameter casing. An internal control valve is integrated in the center of the valve plate assembly.
Technical Paper

A Basic Study on Reduction of Cylinder Block Vibrations for Small Diesel Cars

2000-03-06
2000-01-0527
The production unit number of small diesel engine cars tends to decline except recreational vehicles in Japanese market in recent years, while the production unit number in Europe market keeps on increasing owing to the merits of the durability and the fuel consumption. The small diesel engines will have to be improved in the near future by solving major problems such as noise and vibration pollution, environmental pollution, improvement in performance of diesel engines, in order to expand the production of the engines. This paper refers to a basic study on the experimental and analytical methods for the reduction of resonant vibration in each vibration mode on some cylinder blocks of small high-speed diesel engines in rated engine speed range. Hammering test method, which is easy and useful for measuring frequency response functions, is carried out in the experiments.
Technical Paper

A Basis for Estimating Mechanical Efficiency and Life of a Diesel Engine from its Size, Load Factor and Piston Speed

2011-09-13
2011-01-2211
Parameters like brake mean effective pressure, mean velocity of the piston, hardness of the wear surface, oil film thickness, and surface areas of critical wear parts are similar for all the diesel engines. The mean piston velocity at the rated speed is nearly the same for all the diesel engines. The mechanical efficiency normalized to an arbitrary brake mean effective pressure (bmep) is dependent on the size of the engine. The engine life seems to be proportional directly to the square of a characteristic dimension namely, cylinder bore of the engine and inversely to speed and load factor for engines varying widely in sizes and ratings.
Technical Paper

A Big Size Rapid Compression Machine for Fundamental Studies of Diesel Combustion

1981-09-01
811004
As a basic tool for fundamental studies on combustion and heat transfer in diesel engines, a new rapid compression machine with a cylinder bore of 200 mm was developed which can realize in it a free diesel flame in a quiescent atmosphere, a diesel flame in a swirl, and a diesel flame impinging on the wall. The piston of this machine is driven by high pressure nitrogen, and its speed is controlled by a sophisticated hydraulic system. This paper describes the details of the mechanism and performances of the machine, and presents some examples of studies conducted with this machine.
Technical Paper

A CNG Specific Fuel Injector Using Latching Solenoid Technology

1995-08-01
951914
An advanced fuel injector designed specifically for low energy density gaseous fuels has been developed which demonstrates compelling performance advantages over fuel injectors utilizing conventional solenoid technology. The injector incorporates design features that are necessary to optimize the performance for fuels such as CNG, LNG, and propane. This paper provides a background of magnetic latching technology and addresses the application of the technology to an advanced, pressure balanced, gaseous fuel injector. Performance of the injector will be discussed in detail as will features of the injector specifically adapted for gaseous applications. The ability of the injector to solve fuel metering problems facing the industry, such as turn down ratio limitations, accuracy, durability, and compatibility with existing engine electronics, are addressed.
Technical Paper

A CNG Two Stroke Cycle S.I. Engine Using Intermittent Low Pressure Fuel Injection from Scavenging Ports

2008-01-09
2008-28-0004
Performance of a CNG (Compressed natural gas) two stroke cycle S.I. engine using intermittent low pressure fuel injection from scavenging ports is investigated experimentally. The test engine is a two cylinder, 398 cm3, two stroke cycle spark ignition engine. Gaseous fuel injectors are attached at the engine block, and a CNG is injected into the scavenging passage through a fuel injection pipe. The fuel injection pressure is set at 0.255 MPa, and the fuel is injected intermittently during the scavenging process. The length and tip geometry of the fuel injection pipe are varied, and the effect on the engine performance is investigated. Using the scavenging port fuel injection, the BSFC is reduced by 25 %, and the lean burn limit extends from λ = 1.2 to 1.46, at the maximum. The peak of the NOx emission shifts to leaner side, and the THC emission is reduced by 47 % at the maximum.
Technical Paper

A COHERENCE MODEL FOR PISTON-IMPACT GENERATED NOISE

1979-02-01
790274
An experimental study was conducted to investigate piston-impact generated noise in diesel engines. A coherence model was used to represent the noise generating mechanisms of the engine. The model was applied to an in-line turbo-charged diesel engine. Frequency response functions were measured between the cylinder liner vibration and the engine noise, and between the combustion pressure and the engine noise. The noise coherent with piston impacts was separated from the noise coherent with combustion. Guidelines are presented showing how the results of the coherence model may be used for engine design and noise prediction.
Technical Paper

A Chemical Base for Engine Coolant / Antifreeze with Improved Thermal Stability Properties

2001-03-05
2001-01-1182
Increasingly challenging international engine emissions reductions have resulted in some advances in engine emissions technologies that may motivate a change from the customary ethylene glycol and/or propylene glycol bases that have been the mainstay of engine antifreeze formulations for almost a century. The new engines' components, especially exhaust gas recirculation (EGR) devices, generate much greater thermal stress on the engine coolant. The oxidation of ethylene glycol and propylene glycol may be accelerated dramatically, resulting in coolant unsuitable for continued use in as little as a few months. The industry has been working towards extended engine coolant service intervals1,2,3,4, with some recommendations for service extended to as long as five years. It follows, therefore, that a requirement for coolant change at four to six month intervals (due to accelerated oxidation & aging) would be unacceptable to vehicle owners.
Technical Paper

A Combustion Model for Analyzing the Effects of Natural Gas Composition on the Operation of a Spark Ignition Engine

2002-07-09
2002-01-2236
The combustion of natural gas under lean premixed conditions is of current interest because it has properties that can lead to a potential decrease in pollutant formation and a high efficiency. The composition of the fuel mixture can vary depending upon its origin and can bring about significant changes in the combustion characteristics. This paper presents the experimental results of a single cylinder spark ignition engine fuelled with various natural gas compositions in lean mixture, and describes a numerical model that accounts for variations in concentrations of the fuel components. The diagnostic combustion model is based on the conventional one-zone approach. This thermodynamic analysis is coupled with a numerical resolution of energy and species conservation equations, which incorporates a detailed chemical kinetics. The numerical results demonstrate the influence of the fuel mixture composition on mass burn rates and burning velocities.
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