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Training / Education
2015-06-26
Most muffler design in the automotive industry is accomplished by using "cut-and-try" methods that rely on what has worked in the past and/or extensive full-scale testing on engines for validation. New computer software aimed at muffler design can shorten the design cycle and yield more effective results. This four hour seminar provides an introduction to the behavior of mufflers and silencers including a description of the two-port approach to muffler design. This seminar covers the acoustic simulation of muffler and silencer systems and the use of experimental methods to measure muffler performance. Following a review of basic muffler concepts and definitions, this seminar will focus on meeting design objectives such as insertion loss with a specified back pressure requirement. This seminar will show how modern software such as SIDLAB can be used to model both the acoustics and flow in achieving the design objective and the role that 1D engine simulations can play in providing important input.
Event
2014-10-20
The spectrum of papers solicited for this session reflect the truly multi-disciplinary nature of the field of Multi-Dimensional Engine Modeling. The session covers advances in the development and application of models and tools involved in multi-dimensional engine modeling. This includes advances in chemical kinetics, combustion and spray modeling, turbulence, heat transfer, mesh generation, and approaches targeting improved computational efficiency. Papers employing multi-dimensional modeling to gain a deeper understanding of processes related to turbulent transport, transient phenomena, and chemically reacting, two-phase flows are also encouraged.
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
Lukasz Grabowski
The research on the project to develop a new type of gyroplane required a special gyroplane powertrain to be developed. To meet special research requirements, the correct cooling of a drive unit is particularly important so this paper puts a focus just on the issues of gyroplane powertrain cooling. The Rotax 912S engine was selected as a drive unit following a detailed analysis. A one-dimensional model, simulated with the AVL Boost software, was applied to determine the heat balance for this engine and heat flux penetrating through each engine surface. The geometrical quantities defined in the model were obtained by measuring a three-dimensional geometry provided by an authorized Rotax engine supplier company. It has been shown that 6 kW is absorbed by a direct cooling cylinder, 28 kW by indirect cooling heads and the rest of heat is absorbed by engine oil, the heat due to friction in connecting rod bearing and camshaft bearing and the friction between piston rings and a cylinder surface.
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
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
Beini Zhou, Akira Kikusato, Kusaka Jin, Yasuhiro Daisho, Kiyotaka Sato, Hidefumi Fujimoto
Diesel engines for automobiles are required to simultaneously comply with the increasingly more stringent emission regulations and fuel economy standards. As a very useful tool, Computational Fluid Dynamics (CFD) has become an effective tool to develop higher efficiency and lower emission diesel engine combustion systems. Direct Numerical Simulation (DNS) is one of the most precise methods of all CFD codes. Although DNS can describe organized vortex structures in the turbulent flows, it requires excessive cost and computation time to predict diesel spray characteristics. Thus, so far DNS is not a practical method without adopting turbulent modeling for practical applications. In recent years, Large Eddy Simulation (LES) of turbulent combustion is becoming more popular in the field of fluid mechanics as a practical DNS replacement to analyze in-cylinder turbulent phenomena. Thus, in this study, the soot formation process in diesel combustion was analyzed by using LES based on one-equation sub-grid turbulent kinetic energy model.
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
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
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
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
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
Michal Bialy
By reducing fuel consumption, and even replacing a fuel with a different type, it has been attempted to find the methods to reduce carbon dioxide emissions and costs due to the operation of automotive vehicles. Original fuels are replaced with renewable energy sources such as hydrogen or alcohols. Diesel oil is replaced in a diesel engine with a gaseous fuel. This replacement is accompanied by engine modification involving fitting an engine with an ignition system and reducing the compression ratio. Accordingly, a drive unit can be supplied with one type of fuel only, i.e. a gaseous fuel. Another way is to supply the additional portion of fuel into an intake manifold which is combusted in a combustion chamber together with the original fuel. To avoid knock, the additional portion of fuel is a dozen percents of a master dosage. Therefore, the best solution seems to be dual-fuel supply in a drive unit. A gaseous fuel which is compressed natural gas (CNG) is injected directly into an engine working space, and combustion is initiated with injecting a pilot dose of diesel oil.
Technical Paper
2014-10-13
Konrad Pietrykowski
The paper presents the convective heat transfer phenomenon by analytically and empirically taken data and CFD based model analysis. The 1000hp ASz-62IR aircraft radial engine is the object of research. This engine is still operated on M18 Dromader and AN-2 aircraft. To recount heat oriented phenomena, a three-dimensional CFD model was developed to account circumfluent flow around cylinder and cylinder head engine surfaces. The geometry includes M18 Dromader frontal airframe elements to account their influence on cooling air flow. The simulation has been conducted as a steady-state flow. Engine’s inner wall temperatures that result from mixture combustion heat flow has been set up based on empirical thermocouple indications taken from under sparkplug location. The boundary velocity value that has a crucial influence on heat transfer coefficient has been calculated following Froude-Rankine momentum theory. Geometry and setup specific swirls and backflows were observed. They increase cylinder and head rear side heat transfer coefficients, which is caused by local low pressure areas.
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
Akira Kikusato, Beini Zhou, Kusaka Jin, Yasuhiro Daisho, Kiyotaka Sato
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
Martin Söder, Lisa Prahl Wittberg PhD, Bjorn Lindgren PhD, 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
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.
Magazine
2014-07-09
Simulations for safety Improved design tools let aircraft developers ensure that systems, software, and mechanical elements all work together.
Technical Paper
2014-06-30
Barry M. James, Andreas Hofmann
Abstract The noise performance of fully electric vehicles is essential to ensure that they gain market acceptance. This can be a challenge for several reasons. Firstly, there is no masking from the internal combustion engine. Next, there is pressure to move to cost-efficient motor designs such as Switched Reluctance Motors, which have worse vibro-acoustic behaviour than their Permanent Magnet counterparts. Finally, power-dense, higher speed motors run closer fundamental frequency to the structural resonances of the system [1]. Experience has shown that this challenge is frequently not met. Reputable suppliers have designed and developed their “quiet” subsystems to state of the art levels, only to discover that the assembled E-powertrain is unacceptably noisy. The paper describes the process and arising results for the noise simulation of the complete powertrain. The dynamic properties are efficiently modelled as a complete system and subjected to motor excitation (torque ripple, electro-magnetic forces and rotor imbalance).
Magazine
2014-06-05
Watching for ways to stand above the crowd Sensors monitor a broad range of parameters to help powertrain design teams add features and improve performance.
Magazine
2014-06-02
Europe's aerospace industry looking confident Apart from Airbus's highly visible presence in defense and commercial aircraft, Europe also has successful capabilities in helicopters, business jets, and aero engines, and in all these areas their global market share is growing. Comparing blade-element momentum modeling to 3-D CFD Many small unmanned aerial vehicles (SUAVs) are driven by small scale, fixed blade propellers, and the flow produced by the propeller can have a significant impact on the aerodynamics of the SUAV itself.
Magazine
2014-05-01
Simulating lightweight vehicles operating on discrete terrain Researchers characterize the mobility of autonomous reconnaissance vehicles on terrain considered to be deformable, and represented as a collection of bodies of spherical shape.
Technical Paper
2014-04-28
Y. S. Thipse
Abstract Hyperelastic material simulations are commonly performed in commercial FE codes due to availability of sophisticated algorithms facilitating virtual characterization of such materials in FEA easily. However, the solution time required is longer in FEA. Especially when excitation frequencies do not interfere with structural modes, flexible multibody simulation offers a lucrative and computationally inexpensive alternative. However, it is difficult to directly characterize hyperelastic materials in commercial MBS simulation codes, so the reduced solution time comes at the cost of decreased simulation accuracy, especially if the designer is provided with crude stress - strain test data. Hence, the need is to overcome the drawbacks in FEA and multibody codes, as well as to leverage best of both these codes simultaneously. A methodology is presented where non-linear stiffness properties of the hyperelastic materials are expressed as an analytical function in terms of constants of hyperelastic constitutive material models.
Technical Paper
2014-04-28
A. R. Kumbhar, S. A. Kulkarni, J. M. Paranjpe, N. V. Karanth
Abstract New process development of forging component require lot of process knowledge and experience. Even lots of trial-and-error methods need to be used to arrive at optimum process and initial billet dimensions. But with help of reliable computer simulation tools, now it is possible to optimize the complete process and billet dimensions without a single forging trial. This saves lot of time, energy and money. Additionally, simulation gives much more insight about the process and possible forging defects. In this paper, a complete forging process was needed to be designed for a complex component. With the help of computer simulation, the complete conventional forging process and modified forging process were simulated and optimized. Forging defects were removed during optimization of the process. Also billet weight optimization was carried out. Deciding the pre-forming shape of the billet was the main challenge. With use of computer simulation, an innovative pre-forming shape was arrived resulting in reducing billet input weight.
Event
2014-04-10
This technical session will showcase the creation and application of various tools that will allow for the design and manufacture of parts, equipment, facilities and tests that eliminate the need for physical part prototyping early in a program. The ability to model various aspects of design, test and manufacturing allows for more accurate, cost effective and faster development and product delivery to market.
Event
2014-04-10
This technical session will showcase the creation and application of various tools that will allow for the design and manufacture of parts, equipment, facilities and tests that eliminate the need for physical part prototyping early in a program. The ability to model various aspects of design, test and manufacturing allows for more accurate, cost effective and faster development and product delivery to market.
Viewing 1 to 30 of 4979

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