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Viewing 1 to 30 of 2136
2016-10-17
Technical Paper
2016-01-2158
Jian Gao, Giacomo Cuneo
In small and compact class vehicles equipped with diesel engines, the 2-valve-per-cylinder design still holds a significant share of the market, notably for European traditional diesel-oriented OEMs. Such engines are very efficient and reasonably fun-to-drive, while being complaint to the increasingly stringent emission regulations, showing the technical and commercial potential of 2-valve engine is far from exhausted. The current work describes the numerical simulation of port-valve-cylinder flow in a 1.2L 2-valve-per-cylinder diesel engine to characterize the performance of its manifold and intake ports at rated power conditions as part of the development activities for this new diesel engine architecture. First, evaluation metrics were defined and analysis procedure was established for CFD assessment of intake manifold performance in multi-cylinder engines.
2016-10-17
Technical Paper
2016-01-2160
Alexander Bech, Paul J. Shayler, Michael McGhee
The application of cylinder deactivation technology to small, three cylinder spark ignition engines has the potential to further improve the part load fuel economy of these downsized engines. Although the technology is well established and proven for larger multi-cylinder engines, this is not the case for the class of 1.0litre, three cylinder engines produced by several OEM’s for use in small cars. Deactivating one cylinder by leaving the intake and exhaust valves closed and cutting fuelling requires the other two cylinders to produce more work output to compensate. This changes the distribution of heat rejection to the engine structure. The resulting increases in temperature gradients within the engine structure, and transient response times for thermal adjustments following deactivation or reactivation are examples of the uncertainties which the work reported addresses.
2016-10-17
Technical Paper
2016-01-2197
Chengjun Du, Mats Andersson, Sven Andersson
Effects of nozzle geometry on diesel spray characteristics were studied in a spray chamber using three single-hole nozzles, one cylindrical and two conical, designated N1 (outlet diameter 140 µm, k-factor 0), N2 (outlet diameter 140 µm, k-factor 2) and N3 (outlet diameter 136 µm, k-factor 2). To characterize the hydraulic properties of the nozzles, impingement measurements were carried out under ambient conditions and injection pressures ranging from 800 to 1600 bar. Spray experiments were performed with each of these nozzles at two constant gas densities (15 and 30 kg/m3), one temperature 673 K, at which evaporation occurs. A light absorption scattering technique using visible and UV light was implemented, and the liquid and vapor phase distributions were imaged. The data show that effects of nozzle geometry on the vapor phase penetration and local spray cone angle differ with gas density and injection pressure.
2016-10-17
Technical Paper
2016-01-2191
Peter Deckelmann, Tina Dietrich
This paper will focus on a powertrain injector application (PIA) solution for R&D and production. PIA is a product for triggering and analyzing current and newly developed injection valves (both piezo and solenoid). The article examines an important obstacle of injection testing, which is creating realistic environmental conditions for injectors. It shows, how PIA realizes this through high-end ECU simulation for current and new generations, creating different operating conditions. Berghof Testing combined control, performance and measuring technology into PIA. The compact, intelligent and economical device can be integrated into all existing injector test systems. In addition to the standard version the application offers enhancements such as intelligent injections, injector calibration, polarity detection and image processing for spray analyses. This excludes evaluations based on erroneous fundamentals of the injection behavior to make sure injection can in fact get cleaner.
2016-10-17
Technical Paper
2016-01-2198
Chikara Dodate, Sachio Mori, Masato Kawauchi, Rio Shimizu
In recent years, a lot of direct-injection gasoline engines are developed due to the high rated power, low end torque and fuel efficiency because of increased volumetric efficiency and reduced knocking. On the other hand, the measure for particular matters (PM) and the oil dilution become important. Therefore it is necessary to identify a spray behavior in cylinder with the combination of flow to design a direct injector. To identify the spray behavior, a CFD analysis has been utilized. However, before it was necessary to fit spray model constants and parameters based on measurement results including a penetration and SMD. Especially, in the case of the nozzle whose sectional area of exit is larger than that of inlet like a fan-shape spray nozzle, the fitting process is complicated, because of an inhomogeneity internal flow. In this study, new simulation method of spray is developed.
2016-10-17
Technical Paper
2016-01-2193
Gen Shibata, Hideyuki Ogawa, Fukei Sha, Kota Tashiro
The diesel particulate filter (DPF) has become widely used in diesel engines, and regular regeneration is necessary to remove particulate matter accumulating on the DPF. This may be achieved with fuel injected after the main combustion is complete, so-called post fuel injection, and supplied to the diesel oxidation catalyst (DOC) upstream of the DPF. This increases the exhaust gas temperature in the DOC and the DPF is regenerated with this high temperature gas flow. In most cases, the post fuel injection takes place at 30-90 CA ATDC, and the fuel may impinge on and adhere to the cylinder liner in some cases. The research group of Buddie and Pischinger have reported oil dilution with the post fuel injection by engine tests and simulations. Such adhering fuel is a cause of worsening fuel consumption.
2016-10-17
Technical Paper
2016-01-2229
Alessio Dulbecco, Stephane Richard, Olivier Laget, Philippe Aubret
Turbulence is a crucial topic to account for when dealing with Spark Ignition (SI) engines. In fact, it is well known that combustion in SI engines strongly depends on in-cylinder turbulence characteristics. By definition turbulence presents three-dimensional features; accordingly, three dimensional approaches are mainly used to investigate the in-cylinder flow and assist the engine design process over a large range of operating conditions. However, SI engine architectures are becoming more and more complex and the generalization of technologies such as Variable Valve Timing (VVT) and Direct Injection (DI) considerably increase the number of degrees of freedom to account for. In this context, the resources demanded by 3D CFD codes hugely increase and car manufacturers privilege system simulation approaches, commonly based on models adopting 0D / 1D formalisms.
2016-10-17
Technical Paper
2016-01-2236
Jann Koch, Guoqing XU, Yuri M. Wright, Konstantinos Boulouchos, Michele Schiliro
Three dimensional reactive CFD plays a crucial role in IC engine development tasks complementing experimental efforts by providing improved understanding of the combustion process. A widely adopted combustion model in the engine community for (partially) premixed combustion is the G-Equation where the flame front is represented by an iso-level of an arbitrary scalar G. A convective-reactive equation for this iso-surface is solved, for which the turbulent flame speed ST must be provided. In this study, the commonly used and well-established Damköhler correlation is compared to a novel, physically sound closure derived from an algebraic closure for the scalar dissipation of reaction progress as proposed by Kolla et al. [1].
2016-10-17
Technical Paper
2016-01-2313
Jianjun Zheng, Zhangsong Zhan, Huixian Shen, Xiaoyong Li, Zhiqin Xu, Yuhang Tang, Xiaodong Chen, Qingqiang Zeng, Huibin Qing, Tiegang Hu
This paper describes a simulation guided design methodology for developing direct injection combustion systems of gasoline engines. The first step is the optimization of engine gas flow. The intake port and runner geometry is optimized by CFD simulations to compromise the engine breath capacity and its tumble flow. Secondly, the piston crown shapes and the injection system designs (injection pressure, hole number, hole size and orientations) are optimized based on dedicated CFD simulation results. Thirdly, different injection strategies are used at different engine operating conditions to achieve best engine performance, split injections being used at cold starting and catalyst heating period to realize stratified charge combustion and fast catalyst light-off, and a single injection being used to achieve homogeneous mixture combustion for almost all other operating conditions.
2016-10-17
Technical Paper
2016-01-2201
Meng Tang, Le Zhao, Seong-Young Lee, Jeffrey Naber
Extensive studies have addressed diesel sprays under vaporizing and combusting conditions respectively, but further insights into the mechanism by which combustion alters the global spray penetration and shape of the spray under diesel engine conditions are needed. Contradictory observations are reported in the literature regarding the combusting diesel spray penetration compared to inert conditions, and it is the objective of this study to provide further insight and analysis on the combusting spray characteristics by expanding the range of operating parameters. Parameters varied in the studies are charge gas conditions including oxygen level (0 %, 15%, 19%), charge density (22.8 & 34.8kg/m3), and charge temperature (800K, 900K & 1050K) for injection pressures of 1200, 1500, and 1800 bar with a single hole injector with a nozzle diameter of 100 μm. These represent conditions for operation of a modern fuel injection system diesel engine at high load with EGR.
2016-10-17
Technical Paper
2016-01-2200
Tobias Knorsch, Philipp Rogler, Maximilian Miller, Wolfram Wiese
In order to satisfy future emission classes, such as the EU6c in particular, the particulate number (PN) of Direct-Injection Spark-Ignition (DISI) engines must be reduced. For these engines, different components influence the combustion process and thus also the formation of soot particles and deposits. Among other engine components, the injector nozzle influences the particulate number and deposits in both fuel spray behavior and nozzle “tip wetting”. In case of non-optimized nozzle layouts, fuel may impinge on piston and liner in an unfavorable way, which implies low-oxygen diffusive combustion by retarded vaporizing wall films. For the tip wetting, wall films are present on the actual surface of the nozzle tip, which is also caused by unadapted nozzles. For non-optimized nozzles, the latter effect can become quite dominant. This paper deals with systematic nozzle development activities towards low-deposit nozzle tips and thus decreasing PN values.
2016-10-17
Technical Paper
2016-01-2278
Ashutosh Gupta, Huifang Shao, Joseph Remias, Joseph Roos, Yinhui Wang, Yan Long, Zhi Wang, Shi-Jin Shuai
Superknock is an undesirable combustion phenomenon that limits the fuel economy, drivability, emissions and durability performance of modern turbocharged engines. Numerous researchers have previously reported that the frequency of super knock is sensitive to engine oil and fuel composition in controlled laboratory and engine-based studies. Several studies indicate that droplets of oil and residual fuel ejected from the piston crevice could play a role. Recent studies by Tsinghua University and Afton Chemical Corporation have demonstrated that controlled injection of oil-fuel droplets into the combustion chamber can induce pre-ignition and superknock. Afton and Tsinghua recently developed a 3D CFD engine simulation which was able to realistically model all of the elementary processes involved in droplet induced pre-ignition. The model was able to successfully simulate droplet induced pre-ignition at conditions where the phenomenon has been experimentally observed.
2016-10-17
Technical Paper
2016-01-2194
Muhsin M. Ameen, Prithwish Kundu, Sibendu Som
In this work, a turbulent combustion model is developed for large eddy simulation (LES) using a novel flamelet tabulation technique based on the framework of the multi-flamelet representative interactive flamelet (RIF) model. The overall aim is to develop a detailed model with elaborate chemistry mechanisms, LES turbulence models and highly resolved grids leveraging the computational cost advantage of a tabulated model. A novel technique of implementing unsteady flamelet libraries without the use of progress variables is proposed. These flamelet libraries use the residence time as one of the independent variables instead of using the traditional progress variable approach. In this study, LES of n-dodecane spray flame is performed using the tabulated turbulent combustion model along with a dynamic structure subgrid model. A high-resolution mesh is employed with a cell size of 62.5 microns in the entire spray and combustion regions.
2016-10-17
Technical Paper
2016-01-2350
Zhien Liu, Jiangmi chen, Sheng-hao Xiao
This paper combines fluid software STAR-CCM+ and finite element software ABAQUS to stimulate the internal field of this Gasoline engine exhaust manifold based on the theory of loose coupling. Through the simulation of car parking cooling - full load condition at full speed, we estimate thermal fatigue life of the exhaust manifold with the plastic strain increment as the evaluation parameters. Results shows that the manifold satisfies the target life performance. Here we also made a consideration about the how the bolt force affects the manifold elastic and plastic material behavior.
2016-10-17
Technical Paper
2016-01-2196
Stefan Stojanovic, Andrew Tebbs, Stephen Samuel, John Durodola
With a push to continuously develop traditional engine technology efficiencies and meet stringent emissions requirements, there is a need to improve the precision of injection rate measurement used to characterise the performance of the fuel injectors. New challenges in precisely characterising injection rate present themselves to the Original Equipment Manufacturers (OEMs), with the additional requirements to measure multiple injection strategies, increased injection pressure and rate features. One commonly used method of measurement is the rate tube injection analyser; it measures the pressure wave caused by the injection within a column of stationary fluid. In a rate tube, one of the significant sources of signal distortion is a result of the injected fluid pressure waves reflected back from the tube termination.
2016-10-17
Technical Paper
2016-01-2235
Prithwish Kundu, Riccardo Scarcelli, Sibendu Som, Andrew Ickes, Yan Wang, John Kiedaisch, M Rajkumar
Heat loss through wall boundaries play a dominant role in the overall performance and efficiency of internal combustion engines. Typical engine simulations use constant temperature wall boundary conditions. These boundary conditions cannot be estimated accurately from experiments due to the complexities involved with engine combustion. As a result they introduce a large uncertainty in engine simulations and serve as a tuning parameter. Modeling the process of heat transfer through the solid walls in an unsteady engine CFD simulation can lead to the development of higher fidelity engine simulation models. These models can be used to study the impact of heat loss on engine efficiency and explore new design methodologies that can reduce heat losses. In this work a single cylinder diesel engine is modeled along with the solid piston coupled to the fluid domain.
2016-09-27
Technical Paper
2016-01-8070
Prasad Vegendla, Tanju Sofu, Rohit Saha, Mahesh Madurai Kumar, Long-Kung Hwang, Steven Dowding
Fan and Fan-shroud design is critical for underhood air flow management. The objective of this work is to demonstrate a method to optimize fan-shroud shape in order to maximize cooling air mass flow rates through the heat exchangers using the Adjoint Solver in STAR-CCM+®. Such techniques using Computational Fluid Dynamics (CFD) analysis enables the automotive/transport industry to reduce the number of costly experiments that they perform. This work presents the use of CFD as a simulation tool to investigate and assess the various factors that can affect the vehicle thermal performance. In heavy-duty trucks, the cooling package includes heat exchangers, fan-shroud, and fan. In this work, the STAR-CCM+® solver was selected and a java macro built to run the primal flow and the adjoint solutions sequentially in an automated fashion.
2016-09-27
Technical Paper
2016-01-8008
Hugh Humphreys, David Bevly
ABSTRACT
2016-09-27
Journal Article
2016-01-8147
Justin J. Novacek, Bhargav Sowmianarayanan
Trailer positioning plays a significant role in the overall aerodynamics of a tractor-trailer combination and varies widely depending on configuration and intended use. In order to minimize aerodynamic drag over a range of trailer positions, adjustable aerodynamic devices may be utilized. For maximum benefit, it is necessary to determine the optimal position of the aerodynamic device for each trailer position. This may be achieved by characterizing a two-dimensional design space consisting of trailer height and tractor-trailer gap length, with aerodynamic drag as the response. CFD simulations carried out using a Lattice-Boltzmann based method were coupled with modeFRONTIER for the creation of multiple Kriging Response Surfaces. Simulations were carried out in multiple phases, allowing for the generation of intermediate response surfaces to estimate predictive error and track response surface convergence.
2016-09-27
Technical Paper
2016-01-8139
Santosh Nalanagula, G T Varadharajan
Aerodynamic drag contributes to 50-60% of fuel consumption in trucks on highways. The limits of conventional wind tunnel testing have forced researchers to study about the drag and ways of reducing it computationally. Due to the stricter norms and eco-friendly approaches, truck manufacturers have begun to invest more for developing truck aerodynamics. This paper evaluates a European vehicle on European conditions. Drag reduction are mostly made by geometric changes. Pressure drag, a major drag for trucks as they run at lower speeds is produced by the shape of the object. Making streamlined bodies as trucks are tougher since it can affect its purpose. Therefore, addition of some components can suffice the needs. The changes in geometry have been implied and analysis for these geometrical changes are done to analyze the better geometry which can provide drag reduction features. The geometrical changes considered are providing side skirts, boattails and roof deflector angle.
2016-09-27
Technical Paper
2016-01-8140
Devaraj Dasarathan, Ashraf Farag, Matthew Ellis
Recent regulations on greenhouse gas (GHG) emission standards for heavy-duty vehicles have prompted government agencies to standardize procedures assessing the aerodynamic performance of Class 8 tractor-trailers. The coastdown test procedure is the primary reference method to assess vehicle drag currently, while other valid alternatives include constant speed testing, computational fluid dynamics (CFD) simulations, and wind tunnel testing. In this paper, we correlate CFD simulation with 1/8th scale wind tunnel testing and highlight the impacts of wind tunnel testing on absolute performance compared to open road, full scale analysis including real world effects such as unsteady wind conditions. All scale model testing and CFD simulations were performed on a Class 8 tractor with a standard 53-foot dry-box trailer. The wind tunnel testing was performed in the Auto Research Center (ARC) wind tunnel.
2016-09-27
Technical Paper
2016-01-8154
Abhijith Balakrishna, Gang Wang
The aerodynamic performance between the gap of a tractor-trailer mounted with a refrigeration unit is studied while another trailer passes by on a freeway using transient computational fluid dynamics. Dynamic Meshing methodology available in Ansys Fluent was used to understand the dynamic pressure and flow regimes in and around the tractor trailer gap in general and refrigeration unit in particular, at various vehicle speeds. The influences of distance between the crossing trailers, speed and gap between the tractor trailers on the pressure distribution on the refrigeration unit have been studied.
2016-09-27
Technical Paper
2016-01-8155
Devaraj Dasarathan, Jonathan Jilesen, David Croteau, Ray Ayala
Side window clarity and its effect on side mirror visibility plays major role in the driver comfort. Driving in inclement weather conditions such as rain can be stressful. Having optimal visibility under these conditions is ideal. However, extreme conditions can overwhelm exterior water management devices, resulting in rivulets of water flowing over the a-pillar and onto the vehicle’s side glass. Once on the side glass, these rivulets and the pooling of water they feed can significantly impair the driver’s ability to see the side mirror or to see outwardly when in situations such as changing lanes. Designing exterior water management features of a vehicle is a challenging exercise as traditionally, physical testing methods first require a full-scale vehicle for evaluations to be possible. Additionally, common water management devices such as grooves and channels often have undesirable aesthetic, drag, and wind noise implications.
2016-09-27
Technical Paper
2016-01-8073
Rohit Saha, Mahesh Madurai Kumar, Long-Kung Hwang, Xingshi Wang, Fengchao Zhang, Xiaodan Zhang, Liu Yagui, Weiqing Sun, Yan Wang, Wei Cheng, Mingjin Lin
Higher heat rejection from engine due to higher emissions level and tighter under-hood packaging space often poses integration challenges for both engine and truck manufacturer. Cummins has to perform physical test for validation of the truck's cooling system capability in Chassis dyno at the end of truck's design stage. Cummins' cooling requirements are not met, usually it becomes a big bottleneck in terms of time and resource to redesign and re-select the cooling system components. So, the selection & verification of cooling module for the truck in early stages of design is critical for integration of engine, cooling module and truck. Use of different tools like 1D (like Kuli & LMS Amesim) and 3D simulation (ANSYS Fluent) tools, in the design phase trucks is demonstrated to analyze and validate the design of medium duty truck cooling system.
2016-09-27
Technical Paper
2016-01-8077
Guanyu Zheng
Urea SCR has become a mainstream technology for EU IV up to EU VI. Computational Fluid Dynamics have been used intensively to guide design for mixing, urea deposit mitigation and pressure. Difficulties arises with respect to (1) the necessity of sub modules used for urea transport; (2) heat transfer models sufficient to capture key physics; (3) necessary chemical reaction schemes to describe major phenomena. Methodology developments are crucial to achieve proper modeling of the system. A urea SCR system is selected as a baseline for CFD methodology improvements. Features of advanced modeling are added progressively. At beginning simple flow is modeled, followed by spray modeling. Liquid film with transient behavior is added. Tests are performed for the urea SCR system, where emission data and urea deposit locations are obtained. The CFD results are compared to the test data.
2016-09-27
Journal Article
2016-01-8022
Petter Ekman, Roland Gardhagen, Torbjörn Virdung, Matts Karlsson
Reducing energy consumption and emissions are ongoing challenges for the transport sector. The increased number of goods transports emphasize these challenges even more, as greenhouse gas emissions from these vehicles has increased by 20 % since 1990 in Sweden. One special case of goods transports is that of timber. Today in Sweden, around 2000 timber trucks transport around six billion ton kilometers every year. For every ton kilometer these vehicles use around 0.25 liter diesel, and there should exist large possibilities to reduce the fuel consumption and the emissions. These timber trucks spend most of their operation time travelling in speeds of around 80 km/h. At this speed aerodynamic drag contributes to around 30% of the total vehicle resistance, which makes the aerodynamic drag a significant part of the energy consumption. One of the big challenges with timber trucks is that they travel empty half of the time.
2016-09-27
Journal Article
2016-01-8016
Devaraj Dasarathan, Matthew Ellis, Surya Chinnamani, Ray Ayala, James Haws
In 2015, the United States Environmental Protection Agency and Department of Transportation’s National Highway Traffic Safety Administration released their proposal for the second phase of regulations to reduce greenhouse gas (GHG) emissions from on-road heavy duty vehicles. This second phase of proposed regulations is similar to the first phase of regulations, that went in to effect on model year 2014 heavy duty vehicle, in that the proposals continue to push for further reductions in GHG emissions. One difference is that this new proposal takes a more systematic approach to reducing emissions by considering the impact that trailers have on the fuel efficiency, and therefore the emissions. The new proposed regulations will continue to allow manufacturers to evaluate aerodynamic performance of designs using alternative methods such as computational fluid dynamics (CFD) simulations and wind tunnel tests. It is important for the industry to have confidence in these alternative methods.
2016-09-27
Journal Article
2016-01-8100
Jordan Kelleher, Nikhil Ajotikar
Piston cooling nozzles/jets play several crucial roles in the power cylinder of an internal combustion engine. Primarily, they help with the thermal management of the piston and provide lubrication to the cylinder liner and the piston’s wrist pin. In order to evaluate the oil jet characteristics from various piston cooling nozzle (PCN) designs, a quantitative and objective process was developed. The PCN characterization began with a computational fluid dynamics (CFD) turbulent model to analyze the mean oil velocity and flow distribution at the nozzle exit/tip. Subsequently, the PCN was tested on a rig for a given oil temperature and pressure. A high-speed camera captured images at 2500 frames per second to observe the evolution of the oil stream as a function of distance from the nozzle exit. An algorithm comprised of standard digital image processing techniques was created to calculate the oil jet width and density.
2016-09-20
Technical Paper
2016-01-2018
Syed J. Khalid
Since the advent of the jet engine continuous improvements have been made toward increasing the specific thrust and specific fuel consumption(SFC). First there was the invention of the low bypass ratio (BPR) turbofan. Then with advances in turbine cooling and materials, which increased the core power, high bypass ratio turbofans became feasible. Increasing design BPR improved not only specific fuel consumption at top of climb maximum power and cruise, but also increased take-off thrust. Then if the high BPR engines are de-rated at sea-level to the required thrust, there is an opportunity to enhance hot section durability, plus extend the generation of the required thrust to a hotter day. Achievement of this capability will be explained with the help of simulation results.is Although high design BPR turbofans have improved cruise specific consumption, further improvement in cruise SFC is possible through on-line control effector perturbations.
2016-09-20
Technical Paper
2016-01-1994
Wei Wu, Yeong-Ren Lin, Louis Chow, Edmund Gyasi, John P. Kizito, Quinn Leland
Abstract For aircraft electromechanical actuator (EMA) cooling applications using forced air produced by axial fans, the main objective in fan design is to generate high static pressure head, high volumetric flow rate, and high efficiency over a wide operating range of rotational speed (1x∼3x) and ambient pressure (0.2∼1 atm). In this paper, a fan design based on a fan diameter of 86 mm, fan depth (thickness) of 25.4 mm, and hub diameter of 48 mm is presented. The blade setting angle and the chord lengths at the leading and trailing edges are varied in their suitable ranges to determine the optimal blade profiles. The fan static pressure head, volumetric flow rate, and flow velocity are calculated at various ambient pressures and rotational speeds. The optimal blade design in terms of maximum total-to-total pressure ratio and efficiency at the design point is obtained via CFD simulation.
Viewing 1 to 30 of 2136

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