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2015-04-14
Technical Paper
2015-01-1373
Yulong Lei, Hui Tang, Xingjun Hu, Ge Lin, Bin Song
With the continuous improvement of the road condition, commercial vehicles get to be faster and more overloaded than before, which puts higher pressure on the vehicle braking system. Conventional friction braking has been difficult to meet the needs of high-power commercial vehicle. The auxiliary brake equipment will become the future trend for commercial vehicle. Hydraulic retarder is superior secondary braking equipment. Previously hydraulic retarder research mainly focus on flow field analysis, the braking torque calculation, cascade system optimization and control methods for hydraulic retarder. The gas-liquid two-phase flow in working chamber is less researched. Based on this, this article discusses on the hydraulic retarder from two aspects, including CFD numerical modeling method, transient characteristics of oil-filling , which provides support for hydraulic retarder design and matching in the vehicle. The main contents and conclusions are as follows: 1.
2015-04-14
Technical Paper
2015-01-1738
Dileep Namdeorao Malkhede, Hemant Khalane
Due to reciprocating nature of IC engine, flow physics in intake manifold is complex and has significant effect on volumetric efficiency. Variable length intake manifold technology offers potential for improving engine performance. This paper therefore investigated effect of intake length on volumetric efficiency for wider range of engine speeds. For this purpose 1-D thermodynamic engine model of a single cylinder 611cc standard CFR engine capable of predicting pressure pulsations in the intake was developed. For validation, pressure pulsations were predicted at two different locations on intake manifold and compared against test data. This model was used to predict volumetric efficiency for different intake lengths and engine speeds. Volumetric efficiency was found to be a function of both engine speed and intake length, more so at higher engine speeds. FFT analysis of intake pressure pulsations during suction stroke and intake valve closed phase was carried out separately.
2015-04-14
Technical Paper
2015-01-1693
Mark Allen, Graham Hargrave, Petros Efthymiou, Viv Page, Jean-Yves Tillier, Chris Holt
It is an engineering requirement that gases entrained in the coolant flow of an engine must be removed to retain cooling performance, while retaining a volume of gas in the header tank for thermal expansion and pressure control. The main gases present are air from filling the system, exhaust emissions from leakage across the head gasket, and also coolant vapour. These gases reduce the performance of the coolant pump and lower the heat transfer coefficient of the fluid. This is due to the reduction in the mass fraction of liquid coolant and the change in fluid turbulence. The aim of the research work contained within this paper was to analyse an existing phase separator using CFD and physical testing to assist in the design of an efficient phase separator.
2015-04-14
Technical Paper
2015-01-0327
Elizabeth M. Patterson, Iman Goldasteh, Salamah Maaita
Recent progress in computer-aided engineering (CAE) has made it possible to model complex interdisciplinary multiphysics analysis. This paper investigated the sequential coupled thermal-structural analysis by examining the associated thermal stresses under simulated operational conditions close to the real situation. An evaluation of exhaust muffler strain due to thermal stresses was made by coupling Star-CCM+ CFD software and ABAQUS structural analysis software. The study was made to evaluate discovered muffler durability test failure and to develop a countermeasure design to prevent future issues. Failure of the muffler internal pipe was discovered after heat cycle durability testing where the internal pipe had broken into two pieces. In the first step, CFD analysis was done by thermo-flow simulation in order to determine the resulting heat distribution on the muffler assembly when subjected to the prescribed peak duty cycle temperature.
2015-04-14
Technical Paper
2015-01-1549
Jonathan Jilesen, Adrian Gaylard, Iwo Spruss, Timo Kuthada, Jochen Wiedemann
Driving when it is raining can be a stressful experience. Having a clear unobstructed view of the vehicles and road around you under these conditions is especially important. Heavy rain conditions can however overwhelm water management devices resulting in water rivulets flowing over the vehicle’s side glass. These rivulets can significantly impair the driver’s ability to see the door mirror, and laterally onto junctions. Designing water management features for vehicles is a challenging venture as testing is not normally conducted until late in the design phase. Additionally traditional water management features such as grooves and channels have both undesirable design and wind noise implications. Having the ability to detect water management issues such as A-pillar overflow earlier in the design cycle is desirable to minimize the negative impact of water management features. Numerical simulation of windscreen water management is desirable for this reason.
2015-04-14
Technical Paper
2015-01-0360
Maryline Leriche, Wolfgang Roessner, Heinrich Reister, Bernhard Weigand
An accurate model to predict the formation of fogging and defogging which occurs for low windshield temperatures is helpful for designing the air-conditioning system in the car. Using a multiphase flow approach and additional user-defined functions within a commercial CFD-software (STAR-CCM+), a model which is able to calculate the amount of water droplets on the windshield from condensation and which causes the fogging is set up. Different parameters like relative humidity, air temperature, mass flow rate and droplet distributions are considered. Because of the condition of the windshield’s surface, the condensation occurs as tiny droplets with different sizes. The distribution of these very small droplets must be obtained to estimate numerically the heat transfer coefficient during the condensation process to predict the defogging time.
2015-04-14
Technical Paper
2015-01-1057
Scott Drennan, Gaurav Kumar, Shaoping Quan, Mingjie Wang
Controlling NOx emissions from vehicles is a key aspect of meeting new regulations for cars and trucks across the world. Selective Catalytic Reduction (SCR) is a NOx reduction option that many engine manufacturers are adopting. The performance of urea injection and mixing upstream of an SCR catalyst is critical in obtaining reliable NOx reduction. Computational Fluid Dynamic (CFD) simulations of urea injection systems have become an important development and diagnostic tool for designers. Designers are interested in applying more accurate spray and kinetic models to their CFD simulations and in reducing mesh generation time. This paper presents the application of an automatically generated Cartesian meshing approach to a urea liquid injection system. Investigations of the impact of injection and operating conditions are presented for a model urea-water injection case.
2015-04-14
Technical Paper
2015-01-0344
Yingchao Zhang, Weijiang Meng, Tao Chen, Yong Hao, Wei Ding
It is known that the automobile cabin thermal comfort, could keep the driver and passengers feel better which has a great effect on traffic safety. In this article, to the FAW truck cab, we did some research about the automobile cabin thermal comfort. Our plan is to calculate the air flow distribution and the temperature in steady and transient state when there is warm or cool flow. The heating and cooling experiment methods standard of cabin are based on the national standard and the automobile industry standard of China. Then the numerical simulation process becomes very important. So we used the commercial CFD code- STAR-CCM+ for study in this paper. Firstly, Geometry Clean up, we should process the cabin and the air conditioning pipe system individually, and make sure the closure of the internal surface and handle the wrap surface of the pipe.
2015-04-14
Technical Paper
2015-01-0349
Suvankar Manna, Yogendra Singh Kushwah
With stringent requirements of fuel efficiency and emissions, the airflow and thermal management within the under-hood environment is gaining significance day by day. While adequate airflow is required for cooling requirements under various vehicle operating conditions, it is also necessary to optimize it for reduced cooling drag and fan power. Hence, the need of the day is to maximize cooling requirements of Condenser, Radiator ,CAC and other heat exchangers with minimal power consumption. To achieve this objective and due to the complicated nature of 3D flow phenomenon within the under-hood environment, it is useful to perform 3D CFD studies during preliminary stages to shorten design time and improve the quality and reliability of product design. In this paper we present the results from a CFD under-hood analysis that was carried out for design, development and optimization of a CRFM (Condenser, Radiator and Fan Module).
2015-04-14
Technical Paper
2015-01-0948
Le (Emma) Zhao, Ahmed Abdul Moiz, Jeffrey Naber, Seong-Young Lee, Sam Barros, William Atkinson
Liquid spray breakup and atomization, two multi-phase phenomena, strongly affect the ignition and combustion processes. High-speed jet-to-jet impingement in water sprays could be an effective phenomenon for the spray propagation and droplet vaporization. To achieve higher vaporization efficiency, impingement from two-hole nozzles is analyzed in this paper. This paper focuses on investigating vaporization mechanism as a function of the impingement location and the collision breakup process provided by two-hole impinging jet nozzles. CFD (Computational Fluid Dynamics) is adopted to do simulation. Lagrangian model is used to predict jet-to-jet impingement and droplet breakup conditions while KH-RT breakup and O’Rourke collision models are implemented for the simulation.
2015-04-14
Technical Paper
2015-01-0376
Tommaso Lucchini, Augusto Della Torre, Gianluca D'Errico, Gianluca Montenegro, Marco Fiocco, Amin Maghbouli
Prediction of in-cylinder flows and fuel-air mixing are two fundamental pre-requisites for a successful simulation of direct-injection engines. Over the years, many efforts were carried out in order to improve available turbulence and spray models. However, enhancements in physical modeling can be drastically affected by mesh structure and quality which can negatively influence the predicted structure of organized charge motions, turbulence generation and interaction between in-cylinder flows and injected sprays. This is even more relevant for modern direct injection engines where multiple injections and control of charge motions are employed in a large portion of the operating map. Currently, two different approaches for mesh generation exist: manual and automatic. The first makes generally possible to generate high-quality meshes but, at the same time, it is very time consuming and not completely free from user errors.
2015-04-14
Technical Paper
2015-01-0382
Johann Spreitzer, Felix Zahradnik, Bernhard Geringer
The aim of this paper is the development of a complete Simulation environment for investigation of gas-dynamic processes and combustion phenomena in rotary engines. This project was done by the Austrian Institute for Powertrains and Automotive Technology of the Vienna University of Technology. Commercially available and in engine process calculation proven Software-Tools have been used as basis. For this, a rotary engine test bench has been established and the real engine has been studied in detail. As analysis tools, in addition to the traditional acquisition of the emitted engine torque, various pressures and temperatures, the recording of the pressure profile in the combustion chamber, as well as in the intake and exhaust ports, were used. The thus obtained data of the test bench were used to develop and validate the methodology for the simulation tools. As basis for the presented 1D-simulation program the commercial program GT-Power of Gamma Technologies, Inc. is used.
2015-04-14
Technical Paper
2015-01-0379
Yongli Qi, Xinyu Ge, Lichun Dong
The Hybrid vehicle engines modified for high exhaust gas recirculation (EGR) is a good choice for high efficiency and low NOx emissions. However, high EGR will dilute the engine charge and may cause serious performance problems such as incomplete combustion, torque fluctuation, and engine misfire. An efficient way to overcome these drawbacks is to intensify tumble leading to increased turbulent intensity at the time of ignition. The enhancement of turbulent intensity will increase flame velocity and improve combustion quality, therefore increasing engine tolerance to higher EGR. To achieve the goal of increasing tolerance to EGR, this work reports a CFD investigation of high tumble intake port design using STAR-CD. The validations had been performed through the comparison with PIV experimental tests.
2015-04-14
Technical Paper
2015-01-0385
Fabian Köpple, Paul Jochmann, Alexander Hettinger, Andreas Kufferath, Michael Bargende
The emission of particulate matter from future gasoline direct-injection (GDI) engines has to be optimized, to comply with more stringent emission standards such as EU6. Therefore, the mechanisms responsible for the formation of particles have to be analyzed in detail. From earlier investigations it is well-known that the deposition of liquid fuel wall films in the combustion chamber is a significant source of particle formation in GDI engines. Capturing the detailed dynamics of the deposited liquid fuel is therefore a key feature for the correct prediction of soot generated in a GDI engine. In a previous study particularly the wall surface temperature and the temperature drop due to the interaction with liquid fuel spray were identified as important parameters influencing the spray-wall interaction and thus the wall film formation (cf. SAE 2013-01-1089).
2015-04-14
Technical Paper
2015-01-0386
Prasanna Chinnathambi, Michael Bunce, Luke Cruff
Evolving emissions and efficiency legislation has fueled the development of ultra-lean burn engine concepts that combine high efficiency with low emissions of NOx. Traditional spark ignition (SI) systems have limitations in terms of available ignition energy and its distribution. Turbulent Jet Ignition (TJI) is a pre-chamber-based combustion system that enables ultra-lean operation through high energy jets acting as a distributed ignition source. Combustion is initiated in the pre-chamber (with or without auxiliary fuel injection) using a spark plug. The resulting flame is quenched in the pre-chamber nozzle thereby generating chemically active turbulent jets which penetrate and reignite in the main-chamber at multiple points after a time delay. In this current work a RANS based multidimensional model is developed and validated for the auxiliary fuel injected TJI combustion system using a commercially available CFD code.
2015-04-14
Technical Paper
2015-01-0393
Alessandro d'Adamo, Fabio Berni, Sebastiano Breda, Mattia Lugli, Stefano Fontanesi, Giuseppe Cantore
Engine downsizing is gaining popularity in the high performance engine market sector, where a new generation of highly downsized engine with specific power outputs around or above 150 HP/litre is emerging. High-boost and downsizing to increase power density and reduce fuel consumption have to face the increased risks of pre-ignition, knock or mega-knock. To counterbalance auto-ignition of fuel/air mixture, currently made turbocharged SI engines usually operate with high fuel enrichments and delayed (sometimes negative) spark advances. The former is responsible for high fuel consumption levels, while the latter induce an even lower A/F ratio (below 11), to limit the turbine inlet temperature, with huge negative effects on BSFC.
2015-04-14
Technical Paper
2015-01-0398
Lorenzo Bartolucci, Stefano Cordiner, Vincenzo Mulone, Vittorio Rocco, Edward Chan
In this paper the effects of the adoption of a Partially Stratified Charge (PSC) combustion strategy on the performance of a lean natural gas fueled engine are compared with the ones obtainable with a strategy based on the traditional Homogeneous Combustion process. To that final aim, a CFD 3D model, based on Large Eddy Simulation, has been used to represent the combustion process on a dynamic full 3D engine mesh, taking into proper account all the different phases (intake, combustion and exhaust). The combustion model has been validated via comparison of the flame front development in a Constant Volume Combustion Chamber (CVCC), and then applied to study a single cylinder engine research engine to have an idea of the impact of the real cylinder flow onto the combustion processes and its influence on the main engine parameters. The benefits of the PSC combustion have been checked via several indicators, such as pressure history, energy heat release and flame front turbulent speed.
2015-04-14
Technical Paper
2015-01-0396
Bryce Charles Thelen, Gerald Gentz, Elisa Toulson
Fully three-dimensional computational fluid dynamic simulations with detailed chemistry of a single-orifice turbulent jet ignition device installed in a rapid compression machine are presented. The simulations were performed using the computational fluid dynamics software CONVERGE and its RANS turbulence models. Simulations of propane fueled combustion are compared to data collected in the optically accessible rapid compression machine that the model’s geometry is based on to establish the validity of the simulations.
2015-04-14
Technical Paper
2015-01-0402
P Brijesh, S Abhishek, S Sreedhara
The mixture generation in diesel engines is mainly driven by the combustion chamber geometry and the fuel spray characteristics. Thus, combustion chamber geometry is considered as an important parameter for engine performance and in-cylinder emission control strategy. In this work, effect of various combustion chamber geometries and nozzle cone angle (nozzle rotational angle in X-Z plane) on in-cylinder processes and emissions has been studied numerically using Converge CFD–tool. The Converge CFD–tool can be used for the simulations of three–dimensional, compressible or in-compressible, chemically reacting transient fluid flows in complex geometries with stationary or moving surfaces. Ease of gridding, adaptive mesh refinement (AMR) capabilities and ease of parallelization made this tool very attractive to solve practical problems.
2015-04-14
Technical Paper
2015-01-0399
Alexander Jaust, Bastian Morcinkowski, Stefan Pischinger, Jens Ewald
In this work, a consistent transport and mixing model is derived and validated that calculates the same mixing in thermodynamic multi-zone space as in spacially resolved physical space. The transport and mixing model is developed using a turbulent channel flow as simplified domain. This physical domain of a direct numerical simulation (DNS) is divided into zones based on the quantitative value of transported scalars. Fluxes between the zones are introduced to describe mixing from the transport equation of the probability density function based on the mixing process in physical space. The mixing process of further scalars can then be carried out with these fluxes instead of solving additional transport equations. The relationship between the exchange flux in phase space and the concept of scalar dissipation are shown and validated by comparison to DNS results.
2015-04-14
Technical Paper
2015-01-1336
Meisam Mehravaran, Yi Zhang
Computational Fluid Dynamics (CFD) has been extensively used in predicting the behavior of automotive components. In the current work the fan, shroud and radiator assembly has been simulated using a less expensive CFD methodology. After validating the CAE tool with the test data, the similar simulation was carried on for 13 different shrouds and the effect of geometrical parameters on airflow was investigated. The CFD data show that the smoothly converging shroud will lead to higher flow rates while cavities and steps will perform as a restriction and degrade the efficiency. Besides, it is seen that decreasing the blade-shroud clearance up to 17 mm will improve the air flow as it prevents the leakage of the pumped flow, but if we go further, the airflow does not increase and may even decrease, which may be explained based on the interference of blade and shroud boundary layer.
2015-04-14
Technical Paper
2015-01-1534
Daisuke Nakamura, Yasuyuki Onishi, Yoshiyasu Takehara
Reducing drag contributes to greater fuel efficiency and exhaust gas reduction. Regarding aerodynamic performance, every detail must be considered and resistance must be reduced. A vehicle’s package design—the vehicle's fundamental framework—must be considered. This paper introduces factors that contribute significantly to drag . The paper also discusses methods for improving aerodynamic performance. To balance exterior design with aerodynamic performance, a shape that improves aerodynamic performance must be proposed early on. We used 1/4 scale clay models to identify and analyze areas having a significant aerodynamic impact. More than 500 total variation measurements were conducted for 16 items. Based on the results of these measurements, analysis of flow-field was conducted using CFD.
2015-04-14
Technical Paper
2015-01-1535
Kentaro Machida, Munetsugu Kaneko, Atsushi Ogawa
Reduction of aerodynamic drag is important to improve fuel economy and mitigate the effects on the global environment. There are other technical issues which severely limit how far the vehicle’s shape can be changed. Reducing drag poses the challenge of efficiently extracting features of improved aerodynamic performance and deciding how to balance drag reduction with other functions, such as crash safety, field of vision, and interior comfort. Under these limitations, it is effective to analyze the flow around the vehicle by CFD (computational fluid dynamics) simulations to establish a drag reduction strategy. The Flow Analysis Simulation Tool (FAST) system performs aerodynamic simulation by linking exterior surface design with predefined platform layout. This allowed engineers to run calculations efficiently, independent of their level of experience in CFD.
2015-04-14
Technical Paper
2015-01-1533
Massimiliana Carello, Serra Andrea, Andrea Giancarlo Airale, Alessandro Ferraris
XAM is a prototype (developed at the Politecnico of Torino) of a two seat city vehicle, equipped with a hybrid propulsion system., to obtain low consumptions and reduced environmental impact. The designing process of this vehicle was carried out keeping attention to the requirements of the weight reduction and of the aerodynamic optimization of the shapes of the body, constitute the main specification considered designing XAM in order to consequently get a reduction of consumptions, while guarantying roominess and comfort. According to this, it has been designed a windscreen that makes a one-piece with the roof in order to avoid any discontinuity and consequently any loss due to whirling dissipations in the intersection area.
2015-04-14
Technical Paper
2015-01-1541
Kuo-Huey Chen, Bahram Khalighi
Various drag reduction strategies have been applied to a full size production pickup truck to evaluate their effectiveness by using a Computational Fluid Dynamics (CFD). The drag reduction devices evaluated in this study were placed at the rear end of the truck bed and the tailgate. Two types of devices were evaluated: (1) boat tail-like extended plates attached to the tailgate and (2) flat plates partially covering the truck bed. The effect of drag reduction by various combination of the above are presented in this paper. Twenty-four configurations were evaluated in the study with the best achievable drag reduction of around 21 counts (ΔCd=0.021). A detailed breakdown of the pressure differentials at the base of the truck is provided in order to understand the flow mechanism for the drag reduction. It is concluded that the added surfaces near the tailgate lower the static pressure on the inner side of the tailgate in addition to the pressure increase at the base.
2015-04-14
Technical Paper
2015-01-1538
Neil Ashton, Alistair Revell
Computational Fluid Dynamics (CFD) has increasingly provided the methodology behind an important design tool for the automotive industry. With a desire to reduce noise levels and improve fuel efficiency, reliable CFD simulations of the complex separated turbulent flow around vehicles is becoming an ever more crucial goal. The Ahmed car body [1] has long been one of the most popular automotive test cases because of detailed experimental data and an extensive record of previous simulations. Unfortunately whilst the Ahmed car body represents some of the key aerodynamic features of a full car (such as the vortex shedding and 3D separation), it is still a much-simplified model. A recent development to bridge this gap between models such as the Ahmed car body and a realistic full car model is the DrivAer model [2]. Together with recent experimental and numerical simulations it represents an excellent open-source full-car test case to validate and develop turbulence models.
2015-04-14
Technical Paper
2015-01-1536
Brett C. Peters, Mesbah Uddin, Jeremy Bain, Alex Curley, Maxwell Henry
Currently, most computational fluid dynamic solvers rely heavily on the robustness of unstructured finite volume discretization to solve complex flows. Finite volume solvers are restricted to second order spatial accuracy while structured finite difference codes can easily resolve up to five orders of spatial discretization and beyond. In order to solve flow around complicated geometries, unstructured finite volume codes are employed to avoid tedious and time consuming hand made structured meshes. By using overset grids and NASA's overset grid solver, OVERFLOW, structured finite difference solutions are easily achievable for complex geometries such as the DrivAer model. This allows for higher order flow structures to be captured as compared to traditional finite volume schemes. The current paper investigates flow field solutions computed with finite volume and finite difference methods for the DrivAer model.
2015-04-14
Technical Paper
2015-01-1558
Amir Kharazi, Edward Duell, Austin Kimbrell, Ann Boh
Unsteady flow over automotive side-view mirrors may cause flow-induced vibrations of the mirror assembly which can result in blurred rear-view images, adversely affecting marketability and driver safety, as well as customer comfort and quality perception. Prior research has identified two mechanisms by which aerodynamically induced vibrations are introduced in the mirror. The first mechanism is unsteady aero pressure loading on the mirror face due to the unsteady wake, causing direct vibration of the mirror glass. The second mechanism, and the focus of this study, is a fluctuating loading on the mirror housing caused by an unsteady separation zone on the outer portion of the housing. A time-dependent Computational Fluid Dynamics (CFD) methodology to correctly model mirror wake behavior, and thereby predict flow-induced mirror vibration to improve performance estimations, was developed.
2015-04-14
Technical Paper
2015-01-0939
Daliang Jing, Shi-Jin Shuai, Zhi Wang, Yanfei Li, Hongming Xu
With the increasing demand of energy conservation and environmental protection, further improvement of fuel efficiency and emission reduction in internal combustion engines are urgently required due to the limited energy reserves, rising price of crude oil and climate change. Gasoline direct injection (GDI) engine plays an important part in this area and has experienced a rapid development during the last decade. The design and optimization of a modern spray-guided GDI engine requires a thorough understanding of the fuel sprays characteristics and atomization process. The fuel spray Computational Fluid Dynamics (CFD) modeling technology can be an effective means to study and predict spray characteristics, and as a consequence, to drastically reduce experimental work during the engine development process. For this reason, an accurate numerical simulation of the spray evolution process is imperative.
2015-04-14
Technical Paper
2015-01-1075
Muhammad Ahmar Zuber, Wan Mohd Faizal Wan Mahmood, Zambri Harun, Zulkhairi Zainol Abidin, Antonino La Rocca, Paul Shayler, Fabrizio Bonatesta
In-cylinder soot particle size and its distribution are of interest to engine designers and researchers as they influence the soot emitted from exhaust tailpipes as well as the soot in oil.  The focus of this present study is to analyse changes in soot particle size along predicted pathlines as they pass through different in-cylinder combustion histories.  The prediction of a soot particle pathline, size and how it is transported in the cylinder of a direct injection diesel engine was performed using post-processed in-cylinder combustion data from Kiva-3v CFD simulations with a series of Matlab routines.  Soot particles were assumed massless and only soot surface growth and oxidation processes were considered in calculating the sizes.  3500 locations at 8° Crank Angle (CA) ATDC were selected inside the engine cylinder at the beginning of the pathline and size calculation.  
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