1,721,058 research outputs found
MotoGP 2007: Criteria for Engine Optimization
No full textThe paper proposes some design criteria for the MotoGP engines, complying with the FIM 2007 Technical Regulations. Five configurations have been considered: 3-cylinder in-line, 4-cylinder in-line, and three V-engines with 4, 5 and 6 cylinders. All the analyzed solutions have been optimized from a fluid-dynamic point of view, by means of 1D engine cycle simulations. Then, the engines are compared in terms of full load performance, at steady conditions. Finally, the influence of engine performance, along with operations regularity and motorbike weight, is assessed by means of a lap time simulator, developed by the author on the base of real data. The best configurations turned out to be the 4-cylinder engines, while 3-cylinder and 5-cylinder are quite penalizing
MotoGP 2007: Criteria for Engine Optimization
No full textThe paper proposes some design criteria for the MotoGP engines, complying with the FIM 2007 Technical Regulations.Five configurations have been considered: 3-cylinder in-line, 4-cylinder in-line, and three V-engines with 4, 5 and 6 cylinders.All the analyzed solutions have been optimized from a fluid-dynamic point of view, by means of 1D engine cycle simulations. Then, the engines are compared in terms of full load performance, at steady conditions.Finally, the influence of engine performance, along with operations regularity and motorbike weight, is assessed by means of a lap time simulator, developed by the author on the base of real data. The best configurations turned out to be the 4-cylinder engines, while 3-cylinder and 5-cylinder are quite penalizing.The key of the 4-cylinder success is the good breathing capability and mechanical efficiency at high speed, yielding an optimum power to weight ratio, associated to a good engine regularity, i.e. a smooth response to throttle angle variations
Virtual design of a novel two-stroke high-speed direct-injection diesel engine
No full textThe paper reviews the virtual design process of an automotive HSDI 2-Stroke Diesel engine, developed at the Department of Mechanical and Civil Engineering (DIMeC) of the University of Modena and Reggio Emilia. The new concept of the engine is the tumble supported and spray controlled combustion system, which enables the adoption of loop scavenging without valves, and the use of a very simple and compact combustion chamber, carved in the engine headThe concept has been applied to a 3 cylinder engine, with a capacity of 1050 cm3, supercharged by means of a Roots compressor and a variable geometry turbocharger. Some alternative configurations have been defined.Integrated 1D and multi-dimensional CFD simulations have been performed in order to optimize the main engine parameters, as well as to predict brake performance and emissions, in comparison to a reference four stroke automobile Diesel engine.Simulations results demonstrate the potential of the concept, which may be applied to develop a new generation of ultra-compact and clean automotive Diesel engine
Comparison among different 2-Stage Supercharging systems for HSDI Diesel engines
No full text2-stage supercharging applied to HSDI Diesel engines appears a promising solution for enhancing rated power, low end torque, transient response and hence the launch characteristics of a vehicle. However, many open points still remain, in particular about the impact on emissions control and fuel economy at partial load conditions, generally requiring both high airflow and high EGR rates.The paper analyzes and compares two types of 2-stage supercharging systems: a) two turbochargers of different size; b) one turbocharger coupled to a positive displacement compressor. The goal of the paper is to assess pro and cons of the most feasible configurations for a typical automobile Diesel engine, complying with Euro V regulations and beyond.The base engine is the 2.8L, 4 cylinder in-line unit produced by VM Motori (Cento, Italy), equipped by a standard variable geometry turbocharger. A 1D thermo-fluid-dynamic model of the Euro V version of the engine was built and calibrated against experiments at the dynamometer bench, at both full and partial load.Using the computational model as a starting base, a large set of alternative supercharging systems has been analyzed. The three best configurations are compared to the base engine at full load, under both steady and transient operations. Also a set of steady points, representing the operations in the NEUDC for a vehicle complying with Euro V regulations is simulated, in order to assess the influence of the supercharging system on fuel consumption and emissions
Comparison between two combustion chambers for a motorcycle racing engine
No full textAn experimental and computational analysis has been performed on the combustion chamber of a two cylinder, four stroke, four valve, spark ignition engine developed by Ducati Motor SpA for the Super Sport Championship. Two cylinder head configurations have been analyzed by using a three dimensional CFD code. Port and valve assemblies do not change. Only the combustion chamber surface changes in order to improve the intake flow. Head flow performances in terms of permeability have been determined by computing the steady discharge coefficients at different valve lifts. These values have also been measured on a steady flow test bench. Head flow performances in terms of flow conditioning, i.e. the attitude to promote tumbling and enhance combustion, have been determined by computing the equivalent solid body tumbling number of the flow field at intake bottom dead center. The modified cylinder head combustion chamber surface produces higher steady discharge coefficients and intake bottom dead center tumbling number. Volumetric efficiency and brake mean effective pressure and specific fuel consumption for the steady, wide open throttle operation of the engine have been measured on a steady engine test bench. The full load test has been also simulated by a one dimensional engine cycle code. This simulation provided further information to integrate experimental results
Potential of thermal engine encapsulation on automotive diesel engines - SAE Technical Paper Series 2005-20-067
No full textThermal Engine Encapsulation (TEE) is a technique for reducing heat loss from an engine after it has been switched off, in order to get a warmer re-start. This practice yields benefits in terms of fuel economy, emissions and wear, especially for vehicles used for short journeys in cold weathers and with engines warming up slowly.In this study, the encapsulation of a small automotive Diesel engine is investigated by means of theoretical and experimental analyses. In particular, the influence of oil temperature on brake specific fuel consumption and emissions is calculated. Furthermore, the thermal behavior of the engine has been simulated by a lumped-capacitance model, in order to assess the correlation between encapsulation thickness and cool-down time.Finally, the 0-D thermal model and the 1-D engine model have been coupled in order to predict the influence of engine cranking temperature on fuel consumption and pollutant emissions, considering a B-class vehicle running a short journey (15 minutes) at medium speed and load and very low external temperature (0°C)
The Modular Engine Concept: a Cost Effective Way to Reduce Pollutant Emissions and Fuel Consumption
No full textA promising technique to enhance fuel efficiency of large capacity S.I. engines is the de-activation of some cylinders at partial load, through the cut-out of fuel metering and a specific control of the airflow. Thanks to the ensuing reduction of throttling losses (the active cylinders operate at a much higher load), fuel consumption can be reduced, without any negative perception from the driver. Such a technique has been already applied successfully on some production engines, at the cost of some additional complication on the valve-train system.The application analyzed in this study is a little bit different, being aimed to reduce both fuel consumption and emissions, with a minimum impact on engine design. Larger fuel savings may be obtained by coupling the cylinder de-activation with VVT.However, the most important advantage of the modular engine concept proposed in this paper is in terms of emissions: this study demonstrates that the light-off time of the catalysts may be strongly reduced, and a further improvement is obtained by doubling the effective surface of the catalytic bed.The study has been carried out on a conventional SI 4.2L V8 engine. The first step of the analysis has been the experimental validation of a 1D-CFD model of the engine, achieved with a very good accuracy at both full and partial load. Then, the engine has been simulated on a grid of 15 operating points, representing the usage in the New European Driving cycle. The following configurations have been analyzed and compared to the base engine: 4 active cylinders, 3 active cylinders; 4 active cylinders and optimization of valve timings; 3 active cylinders and optimization of valve timings
On the Numerical Optimization of Acoustic and Brake Engine Performance
No full textOne dimensional CFD codes are standard tools for engine development, in particular for the optimization of intake and exhaust systems. However, the accurate prediction of both engine brake performance and acoustic outputs is not that trivial. A quite critical issue is the modeling of complex engine components, such as air cleaners, plenums, exhaust junctions, silencers, etc. A trade-off is required in order to balance the accuracy of the acoustic analysis and the computational cost, particularly when DOE techniques have to be applie
On the flow modeling through the valve assembly in engine cycle simulations
No full textIn this paper the 1-D modeling of flow through the assembly of valve and port in internal combustion engines is discussed. Three dimensional effects and flow losses close to the valve are accounted for through the experimental effective area, determined at a steady flow bench. The steady flow bench is standard equipment, widely used for engine design and development. The classic method is adequate to the purpose as long as the objective of measuring the effective area is a comparative process for the experimental improvement of the flow through the valves. On the contrary, if the effective area is used for engine cycle simulation, the experimental results must be considered with care
Virtual optimization of a 2-Stroke GDI Range Extender engine
No full textVirtual optimization of a 2-Stroke GDI Range Extender engin
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