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Technical Paper

Toothed Couplings for Diesel Engines: An Example of Steel Substitution With Fiber Reinforced Plastics

1996-04-01
91A100
The replacement with plastic of an important component, formerly in steel, in the timing drive of a heavily duty diesel engine has been studied and realized. The substituted part is the toothed coupling connecting the injection pump to the timing drive. Torque that stresses the coupling has been measured with laboratory tests. The tooth stresses have been calculated with FEM analysis. Finally, fatigue tests have been carried out directly on the engine at different loadings. The test results are consistent with the predicted behavior of this component.
Journal Article

Experimental Investigation of a Double Magnet EMVA at Key-On Engine: A Mechanical Resonance Based Control Strategy

2010-10-25
2010-01-2223
Nowadays, developing of effective camless engine systems, allowing Variable Valve Actuation (VVA), is one of the fundamental automotive challenge to increase engine power, reduce fuel consumption and pollutant emissions, as well as improve the engine efficiency significantly. Electromechanical devices based on double electromagnets have shown to be a promising solution to actuate engine valves during normal engine cycle due to their efficient working principle. Conversely, this solution requires special care at the key-on engine for the first valve lift, when the valve must be shifted from the middle equilibrium position to the closing one with limited coil currents and power requirements as well. Despite the central role of the first catching problem, few attempts have been done into the existing literature to tackle it systematically.
Technical Paper

Development of Fully-Automatic Parallel Algorithms for Mesh Handling in the OpenFOAM®-2.2.x Technology

2013-09-08
2013-24-0027
The current development to set up an automatic procedure for automatic mesh generation and automatic mesh motion for internal combustion engine simulation in OpenFOAM®-2.2.x is here described. In order to automatically generate high-quality meshes of cylinder geometries, some technical issues need to be addressed: 1) automatic mesh generation should be able to control anisotropy and directionality of the grid; 2) during piston and valve motion, cells and faces must be introduced and removed without varying the overall area and volume of the cells, to avoid conservation errors. In particular, interpolation between discrete fields is frequent in computational physics: the use of adaptive and non-conformal meshes necessitates the interpolation of fields between different mesh regions. Interpolation problems also arise in areas such as model coupling, model initialization and visualisation.
Technical Paper

Physical-Chemical Characteristics of Diesel-Biodiesel Blends with Additives and Their Effects on the Spray Behavior

2013-09-08
2013-24-0035
A set of additives was selected to improve the durability of the physical-chemical and biological characteristics of mineral diesel and its blend with biodiesel. Two biodiesels were used: soybean (SME) and rapeseed (RME). Both physical-chemical properties and fuel dispersion of fuel blends and their mixtures with additives were measured that could have effects on the combustion process in diesel engines. The dispersion of the fuel is affected by the injection nozzle integrity, influencing the capacity of the fuel to vaporize, while the modification of the fuel molecular structure can cause changes in combustion reaction. A 7 hole Common Rail (CR) 2nd generation injector, 136 μm in diameter, was used at 80 MPa and 1.0 ms injection pressure and duration, respectively. The injection rate was determined using the Bosch's Method, while the fuel dispersion was measured by analyzing the images of spray evolving in an optical accessible quiescent vessel.
Technical Paper

Tomography of a GDI Spray by PolyCO Based X-Ray Technique

2013-09-08
2013-24-0040
In this paper the investigation with X-ray Tomography on the structure of a gasoline spray from a GDI injector for automotive applications based on polycapillary optics is reported. Table-top experiment using a microfocus Cu Kα X-ray source for radiography and tomography has been used in combination with a polycapillary halflens and a CCD detector. The GDI injector is inserted in a high-pressure rotating device actuated with angular steps Δθ = 1° at the injection pressure of 8.0 MPa. The sinogram reconstruction of the jets by slices permits a 360° spray access to the fuel downstream the nozzle tip. A spatial distribution of the fuel is reported along the direction of six jets giving a measure of the droplet concentration in a circle of 16 mm2 below the nozzle tip at atmospheric backpressure and ambient temperature.
Journal Article

Functional Requirements to Exceed the 100 kW/l Milestone for High Power Density Automotive Diesel Engines

2017-09-04
2017-24-0072
The paper describes the challenges and results achieved in developing a new high-speed Diesel combustion system capable of exceeding the imaginative threshold of 100 kW/l. High-performance, state-of-art prototype components from automotive diesel technology were provided in order to set-up a single-cylinder research engine demonstrator. Key design parameters were identified in terms boost, engine speed, fuel injection pressure and injector nozzle flow rates. In this regard, an advanced piezo injection system capable of 3000 bar of maximum injection pressure was selected, coupled to a robust base engine featuring ω-shaped combustion bowl and low swirl intake ports. The matching among the above-described elements has been thoroughly examined and experimentally parameterized.
Technical Paper

A Low Cost System for Active Gear Shift and Clutch Control

2015-04-14
2015-01-0228
The objective of this study is to demonstrate the design and construction of an innovative active gear-shift and clutch for racecars, applied to a Formula Student car, based on the use of DC gear-motors. Racecars require extremely quick gear-shifts and every system to be as light as possible. The proposed solution is designed to reduce energy consumption, weight and improve gear-shift precision compared to traditionally employed electro-hydraulic solutions, although maintaining state of the art performances.
Technical Paper

Effects of Fuel Temperature and Ambient Pressure on a GDI Swirled Injector Spray

2000-06-19
2000-01-1901
The effects of fuel temperature on both the geometry and the droplet size and velocity of a GDI swirled injector spray were investigated by means of visualizations and PDA measurements. Isooctane was used as model fuel and was injected in a quiescent bomb at injection pressure of 7 MPa. Bomb pressure ranged from 40 kPa to 800 kPa with injector nozzle temperature ranging from 293 K to 393 K. A drastic change in spray geometry was observed when conditions above the vaporization curve were reached. The temperature increase has two macroscopic effects on the spray geometry: at the nozzle exit the liquid flash boiling strongly enlarges the spray angle, at a certain distance from the nozzle the air entrainment collapses the spray. Raising the fuel temperature up to flash boiling conditions causes a significant decrease of the average droplet size.
Technical Paper

Effect of Gas Density and Temperature on Air Entrainment in a Transient Diesel Spray

1996-02-01
960862
The air entrainment in a transient diesel spray was studied using laser Doppler anemometry to provide information on the effect of gas density and temperature. The spray was injected vertically into a confined quiescent atmosphere and the entrained mass flow rate was evaluated by measuring the air velocity component normal to a cylindrical geometric surface surrounding the spray, and extending to about 200 nozzle diameters (50 mm). The experimental results, relative to a density range from 0.84 to 7.02 kg/m3 and a temperature range from 293 to 473 K, indicate that the non dimensional entrainment rate, averaged in time over the main injection period, depends on the distance from the nozzle and both gas density and temperature. A first analysis, based on the available data, allowed to quantify the dependence and provided a correlation with such variables.
Technical Paper

An Innovative 4WD Controlled Powertrain for High Performance Vehicle

2007-04-16
2007-01-0926
The potentialities shown by controlled differentials is making the automotive industry to explore this field. While VDC systems can only guarantee a safe behaviour at limit, a controlled differential can also increase the handling performance. The system derives from a RWD driveline with a semi-active differential, to which has been added a controlled wet clutch that directly connects the engine to the front axle. This device allows to distribute the drive torque between the two axles. It can be easily understood that in this device the torque distribution doesn't depend only from the central clutch action, but also from the engaged gear. Because of this particular layout this system can't work in the whole gear because thermal problems due to kinematical reasons. So the central clutch controller has to consider the gear position too.
Technical Paper

Flash Boiling Evidences of a Multi-Hole GDI Spray under Engine Conditions by Mie-Scattering Measurements

2015-09-01
2015-01-1945
During an injection process, a fluid undergoes a sudden pressure drop across the nozzle. If the pressure downstream the injector is below the saturation value of the fluid, superheated conditions are reached and thermodynamic instabilities realized. In internal combustion engines, flashing conditions greatly influence atomization and vaporization processes of a fuel as well as the mixture formation and combustion. This paper reports imaging behavior of a fuel under both flash boiling and non-flash boiling conditions. A GDI injector, eight-hole, 15.0 cc/s @ 10 MPa static flow, injected a single-component fluid (iso-octane), generating the spray. Experiments were carried out in an optically-accessible constant-volume quiescent vessel by Mie-scattering technique. A C-Mos high-speed camera was used to acquire cycle-resolved images of the spray evolving in the chamber filled with N2 which pressure ranged between 0.05 and 0.3 MPa.
Technical Paper

Experimental Characterization of Methane Direct Injection from an Outward-Opening Poppet-Valve Injector

2019-09-09
2019-24-0135
The in-cylinder direct injection of natural gas can be a further step towards cleaner and more efficient internal combustion engines (ICE). However, the injector design and its characterization, both experimentally and by numerical simulation, is challenging because of the complex fluid dynamics related to gas compressibility and the small length scale. In this work, the under-expanded flow of methane from an outward-opening poppet-valve injector has been experimentally characterized by high-speed schlieren imaging. The investigation has been performed at ambient temperature and pressure and different nozzle pressure ratios (NPR) ranging from 10 to 18. The gaseous jet has been characterized in terms of its macroscale parameters. A scaling-law analysis of the results has been performed. The gas-dynamic structure at the nozzle exit has been also investigated.
Technical Paper

Development and Application of a Quasi-3D Model for the Simulation of Radial Compressors of Turbochargers for Internal Combustion Engines

2019-09-09
2019-24-0187
In this work the 3Dcell method, a quasi3D approach developed by the Internal Combustion Engine Group at Politecnico di Milano, has been extended and applied to the fluid dynamic simulation of turbocharging devices for internal combustion engines, focusing on the compressor side. The 3Dcell is based on a pseudo-staggered leapfrog method applied to the governing equation of a 1D problem arbitrarily oriented in space. The system of equations is solved referring to the relative system in the rotating zone, whereas the absolute reference system has been used elsewhere. The vaneless diffuser has been modelled resorting to the conservation of the angular momentum of the flow stream in the tangential direction, combined with the solution of the momentum equation in the radial direction.
Technical Paper

Analysis of the Cooling Plant of a High Performance Motorbike Engine

2012-04-16
2012-01-0354
This paper is based on a Research Project of the Department of Mechanical Engineering (DiME) in collaboration with Aprilia, the Italian motorbike manufacturer. In an attempt to simulate the functioning of the cooling plant of the Aprilia RSV-4 motorbike a numerical model was constructed using mono-dimensional and three-dimensional simulation codes. Our ultimate aim was to create a simulation model which could be of assistance to engine designers to improve cooling plant performance, thereby reducing research and development costs. The model allows to simulate the running conditions of the whole cooling circuit upon variations in environmental and running conditions. In particular, the centrifugal pump of the cooling plant was simulated by a 3D commercial software, while the whole circuit was built by a 1D commercial code which allows simulation of all the thermal exchanges and pressure drops in the cooling circuit.
Technical Paper

Experimental and Numerical Analysis of Nozzle Flow Number Impact on Full Load Performance of an Euro5 Automotive Diesel Engine

2012-04-16
2012-01-0679
The present paper describes an experimental and numerical study on the effect of the nozzle flow number (FN) on the full load performance of a modern Euro5 diesel automotive engine, in terms of torque, efficiency and exhaust emissions. The improvement of the diesel engine performance requires a continuous development of the engine components, first of all the injection system and in particular the nozzle design. One of the most crucial factors affecting performance and emissions is the nozzle flow number and its influence becomes more and more important as high performance and low emissions are continuous requirements. Indeed, reducing the nozzle flow number, due to an increase of spray-air mixing, an improvement in PM-NOx trade-off is generally expectable. On the other hand, at full load, where peak firing pressure and exhaust valve temperature become the limiting factors, critical operating conditions can be easily reached reducing the nozzle hole diameter.
Technical Paper

Investigation of Diesel Injector Nozzle Flow Number Impact on Spray Formation and Combustion Evolution by Optical Diagnostics

2012-04-16
2012-01-0701
The present paper describes an experimental investigation over the impact of diesel injector nozzle flow number on spray formation and combustion evolution for a modern EURO5 light-duty diesel engine. The analysis has been carried out by coupling the investigations in non evaporative spray bomb to tests in optical single cylinder engine in firing conditions. The research activity, which is the result of a collaborative project between Istituto Motori Napoli - CNR and GM Powertrain Europe, is devoted to understanding the basic operating behaviour of low flow number nozzles which are showing promising improvements in diesel engine behaviour at partial load. In fact, because of the compelling need to push further emission, efficiency, combustion noise and power density capabilities of the last-generation diesel engines, the combination of high injection pressure fuel pumps and low flow number nozzles is general trend among major OEMs.
Technical Paper

Analysis of Diesel Injector Nozzle Flow Number Impact on Emissions and Performance of a Euro5 Automotive Diesel Engine

2012-04-16
2012-01-0891
The present paper describes the results of a research project aimed at studying the impact of nozzle flow number on a Euro5 automotive diesel engine, featuring Closed-Loop Combustion Control. In order to optimize the trade-offs between fuel economy, combustion noise, emissions and power density for the next generation diesel engines, general trend among OEMs is lowering nozzle flow number and, as a consequence, nozzle hole size. In this context, three nozzle configurations have been characterized on a 2.0L Euro5 Common Rail Diesel engine, coupling experimental activities performed on multi-cylinder and optical single cylinder engines to analysis on spray bomb and injector test rigs. More in detail, this paper deeply describes the investigation carried out on the multi-cylinder engine, specifically devoted to the combustion evolution and engine performance analysis, varying the injector flow number.
Technical Paper

CFD Optimization of n-Butanol Mixture Preparation and Combustion in an Research GDI Engine

2017-09-04
2017-24-0063
The recent interest in alternative non-fossil fuels has led researchers to evaluate several alcohol-based formulations. However, one of the main requirements for innovative fuels is to be compatible with existing units’ hardware, so that full replacement or smart flexible-fuel strategies can be smoothly adopted. n-Butanol is considered as a promising candidate to replace commercial gasoline, given its ease of production from bio-mass and its main physical and chemical properties similar to those of Gasoline. The compared behavior of n-butanol and gasoline was analyzed in an optically-accessible DISI engine in a previous paper [1]. CFD simulations explained the main outcomes of the experimental campaign in terms of combustion behavior for two operating conditions. In particular, the first-order role of the slower evaporation rate of n-butanol compared to gasoline was highlighted when the two fuels were operated under the same injection phasing.
Technical Paper

Analysis of a Prototype High-Pressure “Hollow Cone Spray” Diesel Injector Performance in Optical and Metal Research Engines

2017-09-04
2017-24-0073
Technologies for direct injection of fuel in compression ignition engines are in continuous development. One of the most investigated components of this system is the injector; in particular, main attention is given to the nozzle characteristics as hole diameter, number, internal shape, and opening angle. The reduction of nozzle hole diameter seems the simplest way to increase the average fuel velocity and to promote the atomization process. On the other hand, the number of holes must increase to keep the desired mass flow rate. On this basis, a new logic has been applied for the development of the next generation of injectors. The tendency to increase the nozzle number and to reduce the diameter has led to the replacement of the nozzle with a circular plate that moves vertically. The plate motion allows to obtain an annulus area for the delivery of the fuel on 360 degrees; while the plate lift permits to vary the atomization level of the spray.
Technical Paper

Statistical Determination of Local Driving Cycles Based on Experimental Campaign as WLTC Real Approach

2017-09-04
2017-24-0138
In the context of a transport sustainability, some solutions could be proposed from the integration of many disciplines, architects, environmentalists, policy makers, and consequently it may be addressed with different approaches. These solutions would be applied at different geographical levels, i.e. national, regional or urban scale. Moreover, the assessment of cars emissions in real use plays a fundamental role for their reductions. This is also the direction of the new harmonized test procedures (WLTP). Furthermore, it is fundamental to keep in mind that the new WLTC cycle will reproduce a situation closer to the reality comparing to the EUDC/NEDC driving cycle. In this paper, we will be focused on vehicle kinematic evaluation aimed at valuation of traffic situation and emissions.
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