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Technical Paper
2014-11-11
Giovanni Vichi, Luca Romani, Giovanni Ferrara, Luca Carmignani, Francesco Maiani
In the last years, the engineering in the automotive industry has been revolutionized by the continuous research in the reduction of consumption and pollutant emissions. On this topic there is the maximum attention both by the legislative bodies and by the costumers. The more and more severe limitations in pollutant and CO2 emissions imposed by international standards on the engine manufacturers and the increasing price of the fuel force the automotive research to more efficient and ecological engines. The standard approach for the definition of the engine parameters at the beginning of the design process is based on wide open throttle condition although, both in homologation cycles and in the real utilization, engines work mainly in partial load where the efficiency dramatically decreases. This aspect has recently become strongly relevant also for two-wheels vehicles especially for urban purpose. Within this context the authors developed an integrated numerical model, in MatLab Simulink ambient, in order to couple the engine simulation, performed by means of a 1D computer-aided engineering code, with the whole vehicle dynamic behaviour.
Technical Paper
2014-11-11
Rama Subbu, Baskar Anthony Samy, Piyush Mani Sharma, Prasanna Mahendiran
Ride comfort, driving stability and drivability are vital factors in terms of vehicle performance and the customer satisfaction. Crankshaft balancing is the source for the vibration that reduces the vehicle performance and it need to be controlled to some extent such that the vehicle performance will be improved. The IC engine is made up of reciprocating and rotating parts and they produce unbalanced forces during their operation and produce the vibratory output at the vehicle supporting members. The vibration reduction will be possible by minimizing unbalanced forces and by optimizing the crankshaft at the two wheeled vehicle engine design. Many researches were made to find the causes for the vibration and to reduce the vibrations at the engine supports. But still there is a research gap on the testing and simulation of engine components (crankshaft, connecting rod and piston assembly) and the correlation between the testing and simulation. In this work, an attempt is made to represent the engine vibrations and its isolations and to provide a gate way for the future work on it.
Technical Paper
2014-11-11
Mohamed El Morsy, Gabriela Achtenova
Through PULSE platform for vibration analysis, which is developed as an advanced solution for vibration measurements was developed the robust diagnostic concept (RDC). The PULSE setup is designed to help in fault diagnosis of vehicle gearbox -the main part of vehicle powertrain-. Time Domain, Continuous Wavelet Transformation Technique (CWT), FFT and Order analysis measurements are used for detection of an artificial pitting defect in gear by tracking the gearbox response at accelerated speed and different load. The test stand is equipped with three dynamometers; the input dynamometer serves as internal combustion engine, the output dynamometers introduce the load on the flanges of output joint shafts. The pitting defect is manufactured on the tooth side of gear of the fifth speed on the intermediate shaft. Temperature effect on the vibration measurements has been also investigated to study its effect on the fault diagnosis. The presented concept has an important application in the field of mechanical fault diagnosis.
Technical Paper
2014-11-11
Akira Ishibashi, Muneaki Nakamura, Hitoshi Muramatsu
Fuel economy improvement has become the most important issue in automobile engine developments nowadays. For the purpose of improving fuel economy due to the higher thermal efficiency, the enhancement of compression ratio and the reduction of thermal loss through cooling have been conducted widely. Those efforts exerted in the ongoing developments to improve thermal efficiency increase the thermal load on pistons. Considering the reliability of the pistons and anti-knocking capacity of engines, it is necessary to make a better understanding of piston temperature distributions through accurate measurement under various engine operating conditions. Thus, direct and indirect measurement methods have been developed to estimate the actual piston temperature. The direct method, such as linkage-type is not typically available under higher engine speed due to the durability of linkages. The indirect method, such as material hardness-type can neither measure real-time piston temperature nor measure temperature of piston skirts which are thin-walled.    
Technical Paper
2014-11-11
Francesco Maiani, Alessio Sisi, Walther Leardini
In recent years the 2-wheelers engines companies are focused on increasing the overall engine efficiency, that can be gained through engine down-speeding, engine down-sizing and by reducing the frictions; however, to maintain or improve vehicle performance, it is necessary to provide a corresponding increase in specific power. In accordance with these trends, the studied approaches and methodologies have been exploited, during the development of the new Piaggio small scooter engine. In this work a multi-target analysis has been applied to the valvetrain system design, in order to optimize engine performance in terms of friction reduction, power curve and dynamic response of the timing system. Along with this optimization methodology, a robust design has been studied and applied to make the peak cranking compression pressure insensitive to engine starting device working. These calculation methodologies was achieved using commercial software as GT–SUITE for engine performance and valvetrain simulation and modeFRONTIER for multiobjective optimization analysis.
Technical Paper
2014-11-11
Toshio Watanabe, Hiroki Sakamoto
It is well known that for high-speed planing craft with outboard motor, cavitation occurs around the lower unit(gear case) and propeller blades. There are several kinds of cavitation; (1)Tip vortex cavitation (2)Hub vortex cavitation (3)Sheet cavitation (4)Cloud cavitation (5)Root cavitation Among them ,Cloud cavitation and root cavitation lead to erosion damage on the surface of lower unit and propeller. To prevent from poor appearance or performance deterioration of outboard motor by erosion damage, It is important to simulate the occurrence of erosion in advance at the design stage. In this paper, we propose the new method of predicting the area that erosion occurs using CFD (computational fluid dynamics). In order to simulate cavitation phenomena, basically, we have implemented the CFD analysis using the barotropic model. But the area that cavitation occurs does not correspond to the position of erosion damage. Therefore, we focus on the bubble nucleus which is due to cavitation. First, we predict cavitation phenomena on the basis of single-bubble motion with Rayleigh plesset model.
Technical Paper
2014-11-11
Tomokazu Nomura, Koichiro Matsushita, Yoshihiko Fujii, Hirofumi Fujiwara
To meet growing demands on the fuel economy, various studies have been made to improve thermal efficiency of engines. In spite of such efforts, approximately 30% of fuel energy is still dissipated to the atmosphere finally as cooling loss, through engine parts, coolant and oil. Therefore, if the heat dissipation from the engine is insufficient, the temperature of engine parts rises. An excessively higher engine temperature causes a degradation of engine performance and a deterioration of material strength. Especially in air-cooled engines, there are contradicting demands between the heat dissipation capacity and the light weighted compactness. Therefore, to realize the optimized design for a light and compact engine, a method of a precise temperature prediction is required in the early stage of the development. A number of studies have been made on the cooling performance and the temperature prediction of engines. In many of such studies, temperature of an engine cannot be directly estimated but heat transfer from the engine to the atmosphere and to the coolant are evaluated on the basis of heat transfer coefficients calculated by 3D-CFD.
Technical Paper
2014-11-11
Tatsuhiko Sato, Hirotaka Kurita, Akemi Ito, Hideyuki Iwasaki
The frictional force generated between an actual monolithic aluminum cylinder block and a piston / a piston-ring in a firing mode was measured with using a newly developed floating liner device for the first case in the world. The improvement of fuel consumption is the most important issue for engine manufactures from the viewpoint of energy and environment conservation. The piston-cylinder system plays quite important role for the reduction of the engine friction. For the improvement of the frictional behavior of the piston-cylinder system, it is beneficial to observe and analyze the frictional waveforms during an engine operation. In order to meet the above-mentioned demand, the renewed floating liner device was developed. In the newly developed floating liner device, the actual cylinder block itself was used as a test specimen, whereas a thin-walled cylindrical sleeve should be used as the test specimen in the conventional floating liner device. The measured single cylinder was an aluminum monolithic type made of hypereutectic Al-17Si alloy using a high pressure die casting process.
Technical Paper
2014-11-11
Jonathan Tenenbaum, Michael Shapiro, Leonid Tartakovsky
Two-phase jets are found in a variety of applications, including ink-jet printers, spray cooling, etc. Fuel sprays in internal combustion engines is an application of particular interest because of its direct influence on engine performance, energy efficiency and pollutants formation. Many phenomenological models have been proposed to quantify the temporal behavior of spray properties such as spray penetration with time, spray dispersion angle and cross-sectional averaged fuel concentration. However, most of the existing models have the limitation of providing a one-dimensional description and are thus unable to adequately describe the spatial point-wise spray distribution, in particular the local fuel concentration and mixture velocity. The aim of this study is to develop a more elaborate spray model which allows for calculation of spatial local fuel concentration and mixture velocity. The model is based on the single-phase steady-state laminar axisymmetric jet flow field solution by Schlichting, which is applied for a two-phase jet in the limit of dilute fuel concentration.
Technical Paper
2014-11-11
Yoshihiro Nakagawa, Shinya Takahashi, Mikihito Masaki, Ranju Imao
In brake squeal analysis using FE models, minimizing differences in natural frequency between the measurement and the simulation in each component are a key issue for improvement in reproducibility of brake squeal. In the evaluations of model-measurement correlations in the study of brake discs, if amounts of shifts in natural frequencies and their deviation orientations, between the measured and simulated, have the same tendency in each vibration mode, the gaps between the measurements and simulations are relatively easy to be corrected to match to each other by adjusting parameters of densities and/or Young’s moduli. However, these tendencies in natural frequency differences vary depending on the situations and the opposite tendencies may appear in some cases. In such cases, the model-measurement gaps in natural frequency cannot be adequately reduced by adjusting densities and/or Young’s moduli. The potential cause of this model-measurement gap was assumed to be the residual stresses, which were imposed during the inductive hardening process of the brake disc to increase the hardness of the sliding surfaces.
Technical Paper
2014-10-13
Nicolò Frapolli, Michele Bolla, Konstantinos Boulouchos, Yuri M. Wright
In this study, numerical simulations of in-cylinder processes associated to fuel post-injection in a diesel engine operated at Low Temperature Combustion (LTC) have been performed. An extended Conditional Moment Closure (CMC) model capable of accounting for an arbitrary number of subsequent injections has been employed: instead of a three-feed system, the problem has been described as a sequential two-feed system, with the conditioning scalar being the total mixture fraction. A reduced n-heptane chemical mechanism coupled with a two-equation soot model is employed. Numerical results have been validated with measurements from the optically accessible heavy-duty diesel engine installed at Sandia National Laboratories, comparing apparent heat release rate (AHRR), in-cylinder soot mass evolution and exhaust filter smoke number (FSN) for a wide range of post injection dwell times. Subsequently, numerical investigations on the effects of different post injection timings on soot formation and oxidation processes is presented, with particular emphasis on the role of the increased mixing by post injections.
Technical Paper
2014-10-13
Balaji Bandaru, L. Navaneetha Rao, P. S. S. Babu, Krishna Kumar Varathan, J. Balaji
Abstract The present work describes an approach to predict the vehicle fuel economy by simulating its engine drive cycle on a transient engine dynamometer in an engine testbed. The driving cycles investigated in the current study were generated from the typical experimental data measured on different vehicles ranging from Intermediate Commercial Vehicle (ICV) to Heavy-duty Commercial Vehicle (HCV) in real-world traffic conditions include various cities, highways and village roads in India. Reliability and robustness of the method was studied on various engines with cubic capacity from 3.8 liters to 8 liters using different drive cycles, and the results were discussed. Later, using same measured drive cycles, vehicle fuel economy was predicted by a vehicle simulation tool (AVL CRUISE) and results were compared with experimental data. In addition, engine coolant temperature effect on fuel economy was investigated.
Technical Paper
2014-10-13
Yongqiang Han, Jianjian Kang, Xianfeng Wang, Yang Chen, Zhichao Hu
Energy saving and environment protection has been two major subjects in the development of automobile industry. In the internal combustion engine, about 40% of fuel energy is released into the atmosphere through waste gas. The recovery and utilization of the heat from waste gas can realize the goals of energy saving and cost reducing. In fieldof waste heat recovery, the organic Rankine cycle (ORC) has good prospects and has been widely used.Turbo has been selected firstly as the expander in traditional ORC. However, turbo has disadvantages of high manufacturing cost and narrow applicable range. In this paper, a new organic Rankinecycle coupling free piston (ORC-FP) system used in theinternal combustion engine (ICE) exhaust heatrecovery is proposed and its working principle is introduced in detail.In this system, the free piston with constant force outputfunctions as expander in ORC and operates reciprocally to output workunder the driven of working fluid R245ca,which absorbs heat from waste gas and provides vapor power.
Technical Paper
2014-10-13
Akira Kikusato, Kazuya Kogo, Beini Zhou, Kusaka Jin, Yasuhiro Daisho, Kiyotaka Sato, Hidefumi Fujimoto, Hiroshi Terashima, Youhi Morii
The objective of the present study is to analyze soot formation in diesel engine combustion by using multi-dimensional combustion simulations with a parallelized explicit ODE solver. Diesel engines are characterized by high fuel economy while they are strongly required to reduce emissions. Multi-dimensional simulation with detailed chemical reaction calculations will be more promising and useful to understand the combustion processes, and precisely predict emission characteristics for the essential purpose of meeting future stringent fuel economy and emission regulations. On the other hand, CPU load for detailed chemical reaction calculations is becoming higher because they simultaneously solve the ordinary differential equations in terms of various chemical species derived from the rate of elementary reactions. In fact, series calculations of detailed chemical reactions by using DVODE account for more than 99% of the whole calculation time, which includes the time for solving fuel injection, transport equation and so on.
Technical Paper
2014-10-13
Harun Mohamed Ismail, Hoon Kiat Ng, Suyin Gan, Tommaso Lucchini
Modelling the combustion process of a diesel-biodiesel fuel spray in a 3-dimensional (3D) computational fluid dynamics (CFD) domain remains challenging and time-consuming despite the recent advancement in computing technologies. Accurate representation of the in-cylinder processes is key to the success of CFD studies as they are able to provide invaluable insights into these events, which are limited when using conventional experimental approaches. This is especially true for emerging new fuels such as biodiesels as the fundamental understanding of these fuels under combusting environment is still limited. The reported work here is dedicated to evaluating the Adaptive Local Mesh Refinement (ALMR) approach in OpenFOAM® for accurate simulation of reacting biodiesel-diesel fuel spray. An in-house model for thermo-physical and transport properties is integrated to the code, along with a chemical mechanism comprising 113 species and 399 reactions. Simulation results are compared against data from Chalmers High-Pressure-High-Temperature Constant-Volume Combustion Chamber (HPHT-CVCC) experimental test-bed studies in terms of liquid-droplet penetration length, vapour penetration length and spray temporal distribution.
Technical Paper
2014-10-13
Christopher Bannister
When evaluating the performance of new boosting hardware, it is a challenge to isolate the heat transfer effects inherent within measured turbine and compressor efficiencies. This work documents the construction of a lumped mass turbocharger model in the MatLab Simulink environment capable of predicting turbine and compressor metal and gas outlet temperatures based on measured or simulated inlet conditions. A production turbocharger from a representative 2.2L common rail diesel engine was instrumented to enable accurate gas and wall temperature measurements to be recorded under a variety of engine operating conditions. Initially steady-state testing was undertaken across the engine speed and load range in order that empirical Reynolds-Nusselt heat transfer relationships could be derived and incorporated into the model. Steady state model predictions were validated against further experimental data and an assessment made of the transient performance of the model during tip-in’s and tip-outs.
Technical Paper
2014-10-13
John Thomas
Vehicle manufacturers among others are putting great emphasis on improving fuel economy (FE) of light-duty vehicles in the U.S. market, with significant FE gains being realized in recent years. The U.S. Environmental Protection Agency (EPA) data indicates that the aggregate FE of vehicles produced for the U.S. market has improved by 20% from model year (MY) 2005 to 2013. This steep climb in FE includes changes in vehicle choice, improvements in engine and transmission technology, and reducing aerodynamic drag, rolling resistance, and parasitic losses. The powertrain related improvements focus on optimizing in-use efficiency of the transmission and engine as a system, and may make use of what is termed downsizing and/or downspeeding. This study explores quantifying recent improvements in powertrain efficiency, viewed separately from other vehicle alterations and attributes (noting that most vehicle changes are not completely independent). A methodology is outlined to estimate powertrain efficiency for the U.S city and highway cycle tests using data from the EPA vehicle database.
Technical Paper
2014-10-13
Jacek Andrzej Czarnigowski
The search for environmentally friendly fuels and ways of reducing carbon dioxide emissions is the main cause of a growing interest in gaseous fuels and corresponding fuel systems for internal combustion engines. To assure the expected environmental advantages with no detriment to the engine performance, these fuel systems need to be equipped with precise actuators – the gas injectors. The key input required in the process of designing and calibrating such fuel systems are precise characteristics of the injectors and understanding what affects these characteristics. The paper presents the results of experiments on the effects of supply pressure and supply voltage on the pulse gas injector opening time. Two characteristics have been investigated into: the opening lag time and the opening time. The opening lag was defined as the time between the occurence of a control signal and the moment of the valve’s starting to move. The lag determines the minimal duration of the control signal that can be executed by the injector, and thus the injector’s applicability.
Technical Paper
2014-10-13
Hiew Mun Poon, Hoon Kiat Ng, Suyin Gan, Kar Mun Pang, Jesper Schramm
This is an extension to the previous work conducted by the authors that the chemical kinetic mechanism reduction scheme was improved for large-scale mechanisms. In this work, Perfectly Stirred Reactor (PSR) was added as a criterion of data source for mechanism reduction instead of using auto-ignition condition only in the previous work. The detailed n-hexadecane mechanism with 2116 species and 8130 elementary reactions for diesel fuel surrogate was chosen to perform mechanism reduction. Operating conditions with equivalence ratio ranging from 0.5 to 2, initial pressure ranging from 40 bar to 80 bar, initial temperature ranging from 650 K to 1350 K for auto-ignition and 300 K for PSR as well as residence time covering the ignition and extinction ranges were sampled. As a result, a reduced n-hexadecane mechanism with 79 species for diesel fuel surrogate was successfully derived from the detailed mechanism. Following that, the reduced n-hexadecane mechanism was validated under auto-ignition and PSR conditions using zero-dimensional (0-D) closed homogeneous batch reactor in CHEMKIN-PRO software.
Technical Paper
2014-10-13
Michal Bialy, Miroslaw Wendeker, Pawel Magryta, Zbigniew Czyz, Rafal Sochaczewski
The article presents results of the 3D-CFD modeling of mixture creation process in the cylinder of diesel engine. The simulation was performed using the AVL Fire software. Based on the geometry of the ADCR engine, produced by Andoria-Mot Company, a 3D-CFD model of combustion chamber, channels in the engine head and CNG injector nozzle were created. This model prevented the simulation of the filling, compression and mixture creation process. Specially prepared CNG injector has been placed in the socket of the glow plug, to minimize interference with the structure of the engine. With this solution full functionality of the original fuel supply system was retained with the ability to work with one or two fuels. During studies the location of the gas injector nozzle was changed. The results of simulation are presented for three variants of CNG injector locations. Simulation studies prevented the determination of the degree of stratification and the distribution of fuel in the cylinder of the engine.
Technical Paper
2014-10-13
Zhi Wang, Fang Wang, Shi-Jin Shuai
This paper studied the knock combustionprocess in gasoline HCCI engines. The complex chemical kinetics wasimplemented into the three-dimensional CFD code with LES (Largeeddy simulation) to study the origin of the knock in HCCIcombustion process. The model was validated using the experimentaldata from cylinder pressure measurement and combustion analysis.3D-CFD with LES method gives detailed turbulence, species,temperature and pressure distribution during gasoline HCCIcombustion process. The simulation results indicate that HCCIengine knock originates from random multipoint auto-ignition incombustion chamber due to slight inhomogeneity. It is induced bythe significantly different heat release rate of high temperatureoxidation (HTO) and low temperature oxidation (LTO) and theirinteractions. Pressure wave occurrence can be explained by the factof significant pressure gradients in HCCI combustion field, whichcaused by multipoint auto-ignition in constant-volume like heatrelease. For instance, slightly higher temperature spots wereformed before ignition due to wall heat transfer and turbulenceconversion.
Technical Paper
2014-10-13
Tenghua Shieh, Kiyotaka Yamashita, Oana Nitulescu, Satoshi Hirano, Norio Inami, Hiroshi Moritani
This paper focuses on the fuel contribution to oil degradation especially from the degraded fuel. The polymerization of degraded fuel is responsible for the formation of insoluble which is considered for the cause of low temperature sludge, piston ring deposit and turbo-coking in severe vehicle operating conditions. The main objective of the study is to understand the mechanism of partial oxidants production of fuel in combustion process before mixing with into oil. A numerical method has been established to calculate partial oxidant directly by using 3D CFD with detailed chemistry. A Dynamic Mechanism Reduction with Multizone is implemented to shorten the calculation time. For a two engine cycles with mechanism of 2456 species and 11336 reactions, 20 days with 64 CPUs is possible. To further enhance the capability for sensitivity study in wide range of operating condition, a combination of 3D CFD (with simplified mechanism) and 0D Kinetics (with full mechanism) approach is proposed for realistic turn-around time.
Technical Paper
2014-10-13
Karthik Puduppakkam, Chitralkumar Naik, Ellen Meeks, Christian Krenn, Roswitha Kroiss, Johannes Gelbmann, Guenther Pessl
An important goal for CFD simulation in engine design is to be able to predict the combustion behavior as operating conditions are varied and as hardware is modified. Such predictive capability allows virtual prototyping and optimization of design parameters. For low-temperature combustion conditions, such as with high rates of exhaust-gas recirculation, reliable and accurate predictions have been elusive. Soot has been particularly difficult to predict, due to the dependence of soot formation on the fuel composition and the kinetics detail of the fuel combustion. Soot evolution in diesel engines is impacted by fuel and chemistry effects, as well as by spray dynamics and turbulence. In this work, we present a systematic approach to accurately simulate combustion and emissions in a high-performance BMW diesel engine. This approach has been tested and validated against experimental data for a wide range of operating conditions. Nine operating conditions have been modeled that span engine loads of 3-21 bar MEP, engine speeds of 1000-4400 rpm and external EGR of 0-38%.
Technical Paper
2014-10-13
Chen Huang, Andrei Lipatnikov, Lars Christian Riis Johansen, Stina Hemdal
Direct Injection (DI) of gasoline into combustion chamber of a Spark Ignition (SI) engine is widely recognized to be a promising technology capable for substantially reducing fuel consumption and carbon dioxide emissions. Accordingly, there is a strong need for developing models of some effects specific to stratified turbulent burning under elevated and rapidly varying pressure. Two such effects are addressed in the present work by analyzing simple cases and by performing unsteady three-dimensional RANS simulations of stratified turbulent combustion in a DI SI engine. First, because the rate of an increase (decrease) in enthalpy under the influence of pressure increase (decrease) is inversely proportional to the density, the enthalpy of combustion products is increased (decreased) stronger than the mean enthalpy or the enthalpy of unburned reactants. The difference in the three enthalpies affects the temperature of the products and, therefore, the rate of the thermal NO formation. To the best of the present authors’ knowledge, in CFD research into burning in SI engines, the discussed effects have yet been addressed invoking ill-justified balance equations for the enthalpy conditioned to unburned gas, with these equations being inconsistent with the well-known balance equation for the Favre-averaged enthalpy.
Technical Paper
2014-10-13
Girish V. Nivarti, Jian Huang, W K Bushe
Conditional source-term estimation (CSE) is a novel chemical closure method for the simulation of turbulent combustion. It is less restrictive than flamelet-based models since no assumption is made regarding the combustion regime of the flame; moreover, it is computationally cheaper than conventional CMC models. To date, CSE has only been applied for simulating canonical laboratory flames such as steady Bunsen burner flames. Industry-relevant problems pose the challenge of accurately modelling a transient ignition process in addition to involving complex domain-geometries. In this work, CSE is used to model combustion in a homogeneous-charge natural gas fuelled SI engine. The single cylinder Ricardo Hydra research engine studied here has a relatively simple chamber geometry which is represented by an axisymmetric mesh; moving-mesh simulations are conducted using the open-source CFD software, OpenFOAM. An oxygen-based reaction progress variable is employed as the conditioning variable, and its stochastic behaviour is approximated by the beta-PDF.
Technical Paper
2014-10-13
Fabrizio Bonatesta, Salvatore La Rocca, Edward Hopkins, Daniel Bell
Gasoline Direct Injection engines, even in their latest generation, are an important source of ultra-fine particulate matter. The ever more stringent emission regulations across the globe, along with the renewed medical evidence of the adverse impact on human health, indicate further research is needed to improve design and control of the GDI technology, with the aim of reducing PM emissions. Commonly, two phenomena are reported as the most important sources of soot formation in GDI engines: the inherent poor fuel-air mixture preparation; the interaction between high-velocity fuel spray and combustion chamber walls. Computational Fluid Dynamics modelling is a cost-effective alternative to testing and, if appropriately configured, may offer useful insight into the details of fuel spray and mixture preparation. Given the acknowledged connection between combustion and soot formation processes, CFD modelling may also lead to improved understanding useful for the optimization of combustion control strategies specifically designed to minimise engine-out soot emissions.
Technical Paper
2014-10-13
Arash Hamzehloo, Pavlos Aleiferis
International obligations to reduce carbon dioxide emissions and requirements to strengthen security of fuel supply, indicate a need to diversify towards the use of cleaner and more sustainable fuels. Hydrogen has been recommended as an encouraging gaseous fuel for future road transportation since with reasonable modifications it can be burned in conventional internal combustion engines without producing carbon-based tailpipe emissions. Direct injection of hydrogen into the combustion chamber can be more preferable than port fuel injection since it offers advantages of higher volumetric efficiency and can eliminate abnormal combustion phenomena such as backfiring. The current work applied a fully implicit coupled computational methodology along with Reynolds-Averaged Navier-Stokes (RANS) technique in order to study the mixture formation and combustion in a direct-injection spark-ignition engine with hydrogen fuelling. Hydrogen was issues into the combustion chamber by a six-hole side-mounted injector.
Technical Paper
2014-10-13
Konrad Pietrykowski
Radial aircraft engines were used in aviation since its beginning. Nowadays, there are very few airplanes equipped with this type of engines, however, they are still used and developed. A good example is WSK PZL Kalisz company, which has introduce an electronic fuel injector to the ASz-62IR engine, and in cooperation with Lublin University Technology it has carried out project based on the usage of electronic ignition system in this engine. One of the major difficulties of radial engines is an irregular operation of individual cylinders caused by the unique arrangement of cylinders. Besides, the bore of cylinders very frequently exceed the value of 150 mm, this hinders the combustion of fuel-air mixture. Due to the safety matters and in order to boost the combustion of the mixture, two spark plugs for a cylinder have been used in such engines,. They are placed symmetrically on both sides of a cylinder head. The usage of the electronically controlled injection in combination with two spark plugs provides numerous possibilities of controlling the combustion in the radial engine.
Technical Paper
2014-10-13
Martin Söder, Lisa Prahl Wittberg, Bjorn Lindgren, Laszlo Fuchs
In-cylinder flow structures have a great influence on engine emissions. Therefore, knowledge of how these structures are created during intake and affected by compression is of great importance to reduce fuel consumption and emissions. For compression ignition engines the swirl number is used to characterize the flow field whereas in spark ignited engines the tumble number is used. Tumble breaks down during compression increasing turbulence level and mixing, while swirl is unaffected by compression if no piston bowl is present. The effects of a combined swirl and tumble flow on uniformity, turbulence and mixing properties are however relatively unknown. In this work we study how uniformity, turbulence and mixing are affected by the ratio between swirl and tumble using Large-Eddy Simulations (LES). We have found that increasing tumble raises peak turbulence levels and shifts the peak earlier, leading to higher diffusion. Therefore, it is found that maximum turbulence level at top dead center is obtained with a combination of swirl and tumble.
Technical Paper
2014-10-13
Yufeng Li
Swirl ratio in the cylinder of a diesel engine is an important parameter for air/fuel mixing and combustion process. Swirling flow in the cylinder is formed when the intake air flows thought a helical or tangential port and inlet valve seats and then recognized by the wall of the cylinder. The swirling angular speed generated by the intake ports can be determined on a steady flow rig. The swirl ratio at the end of intake stroke in an operating engine is then estimated by equations which have already been established by Ricardo and AVL. However, the swirl ratio estimated by these existing equations is not the real value in the cylinder of an operating engine as the equations were deducted from three basic assumptions: a) volumetric efficiency of an engine is 100%; b) the pressure drop between the intake ports is constant during the engine operation; c) no burned gas residual is trapped in the cylinder. They are not true definitely. On the other hand, an accurate swirl ratio in the cylinder is essential during the engine development.
Viewing 1 to 30 of 29397