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Viewing 1 to 30 of 17669
Technical Paper
2014-10-13
Hyunsup Yang, Kyung Seok Cho, Chi Yong Park, Dae Bok Keon, Chang Ha Lee, Yong Sun Park
Fuel Cell Electric Vehicles (FCEV) is zero emission vehicles because it produces only water as a byproduct. The other advantages are a long driving range and a quick refueling time compared with the pure electric vehicle. The air compressor supply compressed air to the cathode of fuel cell stack to chemically react with the hydrogen from the compressed hydrogen tank to generate electric power. The majority of the companies have used displacement type screw compressor for their current and next generation air supply systems. The screw type air compressor was used for the supercharged internal combustion engines. Screw type air compressor has some advantage in increasing pressure ratio but it has disadvantage in NVH (Noise, Vibration and harshness), efficiency and productivity. Among them NVH is the greatest factor that inhibits the marketability of FCEV because it has no noise source such as internal combustion engine. Because of that, the screw type air compressor should have very expensive noise cover and muffler for the reducing of the pressure fluctuation to improve NVH level.
Technical Paper
2014-10-13
Rajasekhar MV
In the recent times importance of environmental changes and energy efficiency are the key considerations for any vehicle manufacturer. With the surge in vehicle population exceeding 40 million in India and their adverse effects on environment, government agencies are in a process of implementing stringent norms to curb vehicle pollutions. In these scenarios with fierce competition from around the world, local Vehicle manufactures have to pose a greater challenge on product design aspects of energy efficiency, fuel economy along with low capital cost. In the context of developing countries choosing the right technology such as clean diesels, parallel hybrid, series hybrid, EVs, B-ISG systems etc for the right segment of vehicle can play a major role in making a vehicle a big success. In all these considerations the manufacturer has to meet the requirements along with not exceeding the cost targets. This paper details the approach and strategy for vehicle manufactures to implement different technologies based on the class, segment and cost of the vehicle for achieving the desired results to achieve energy efficiency, environmental efficiency and fuel economy benefits for cost conscious markets of developing countries.
Technical Paper
2014-10-13
Gerhard Kokalj, Patrick Schatz, Christoph Zach
The automotive industry is racing to introduce some degree of hybridization into their product ranges. Since the term “hybrid vehicle” can cover a wide range of differing technologies and drivetrain topologies, this has led to a plethora of vehicles that call themselves “hybrid”. This poses an interesting challenge for marketers to differentiate these vehicles from the incumbents. However, it is not just the marketers who are faced with challenges, the developers of such hybrid drivetrains are faced with a rise in technical complexity due to the wide range of operating modes hybridization introduces. As propulsive torque is being generated in more than one place in a hybrid vehicle, the transitions from conventional drive to electrically supported drive bring with them complex aspects of multi-dimensional system control. The challenge is to be able to implement hybrid technology in an existing drivetrain, while adapting the existing components as required. The functional variability of hybrid technology, however, permits a range of possible implementations and the control calibration tasks themselves need to be well structured concerning hand-over, traceability and robustness.
Technical Paper
2014-10-13
Raja Mazuir Bin Raja Ahsan Shah, Andrew McGordon, Mark Amor-Segan, Paul Jennings
Several studies have shown that a Micro Gas Turbine (MGT) can potentially be used as a range extender for an electric vehicle or a series hybrid electric vehicle. The continuous process of combustion provides advantages in terms of noise, vibration and gaseous emission such as hydro carbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx). Most MGTs have the capability to run on multi fuel without the need to change hardware configuration. The power density of the MGT is much higher than an internal combustion engine due to its less complex design, e.g. no cooling and lubrication systems are required within its architecture. However, not much research has been done to investigate in detail the technical requirements of the MGT from an automotive perspective, particularly the effect of intake temperature (engine bay temperature) on the performance and the tailpipe emissions. Previous work has shown that the engine bay temperature can be significantly higher than the ambient temperature during vehicle hot soak.
Technical Paper
2014-10-13
Stefan Geng, Thomas Schulte
Hybrid electric powertrains are developed for reducing the fuel consumption and the emission of carbon dioxide. In order to achieve a reduction in comparison to conventional vehicles, an improved efficiency of the overall system is required. It depends on the powertrain topology, its components and the applied control strategy. For testing and improving the control strategy in terms of the overall system efficiency, Hardware-in-the-Loop (HIL) simulation can be applied. Thereby, a real-time simulation of the powertrain is used to emulate the behavior of the actuator and sensor signals in order to operate the corresponding electronic control units in a virtual test environment [1], [2]. The development of real-time capable powertrain models is a time-consuming task, due to high dynamics and switching frequencies of the electrical subsystem, comprising the electric drive, inverter and battery and due to the immense diversity of powertrain configurations, comprising the transmission, the combustion engine, the electric drives, etc.
Technical Paper
2014-10-13
Fuyuan Yang, Lei DU, Changsheng Yao, Jiaen Du, Ping Yu
The efficiency of traction motor affects the overall efficiency of city buses which most of time creep among jammed city traffic. The low speed and torque operating condition deviate from the high-efficiency region of electric motor. This paper discusses whether it is possible to improve the motor efficiency by a two-speed transmission and if so, to what extent. In this paper, based on the China Bus Urban Cycle, an 8-meter electric bus is studied, and the comparison of motor efficiency between two different configurations is made: direct drive and drive through a two-speed transmission. In the ‘direct drive’ configuration, the traction motor drives the main reducer directly, while in the other configuration installed a two-speed transmission between. Apart from that, all other specifications are the same. The study is conducted via modeling and simulation in Matlab/Simulink environment. In the simulation of both configurations, models of driver, traction motor, two-speed transmission, the I-curve of braking forces distribution and vehicle controller are built.
Technical Paper
2014-10-13
Boru Jia, Zhengxing Zuo, Huihua Feng, Guohong Tian, A.P. Roskilly
Free-piston engine generator (FPEG) is a novel type of energy conversion device, which integrates a linear combustion engine and a linear electrical machine into a single unit. As an alternative to conventional engines, FPEG is a promising power generation system due to its simplicity and high thermal efficiency and has attracted considerable research interests recently. This paper presents the development for a spark-ignited free-piston engine generator prototype which was rated to 3kW power output, and the designation of major sub-systems is introduced. The electrical linear machine is operated as a linear motor to start the engine and switched to a generator after successful ignition. Closed-loop control strategy was investigated and implemented for the starting process with a constant force provide by the linear machine. Ignition is one of the most crucial problems for the generating process, thus a unique control sub-system to generate ignition signals at the correct ignition timing based on the piston position was completed.
Technical Paper
2014-10-13
Abdelmajid AIT TALEB, Ali chaaba, Mohamed SALLAOU
In the field of machinery, epicyclic gear trains play a fundamental role in power transmission lines. Their use is very wide and varied and they can realize the function of a mechanism as a “differential" or as a mechanism to reduce or increase speeds. For example, the epicyclic gear trains equip a large number of vehicles transmission such as electric and hybrid cars and heavy vehicles, these epicyclic gear trains are integrated especially in continuously variable power split transmissions. The mechanical efficiency assessment of transmissions integrating one or more epicyclic gear trains requires the knowledge of the efficiencies of components setting up the transmission, in particular that of the epicyclic gear trains. The efficiency of these mechanisms is commonly defined as the ratio of the output power by the input one. For a planetary gear train with three active shafts, which operates as a differential system, the definition of the efficiency will not change, but, it is necessary first to identify the powers flow running between its links.
Technical Paper
2014-10-13
Jonathan Hall, Michael Bassett, Hannes Marlok, Marco Warth
In 2012 MAHLE Powertrain unveiled a range-extended electric vehicle (REEV) demonstrator, which is based on a series hybrid configuration, and uses a battery to store electrical energy from the grid. Once the battery state of charge (SOC) is depleted a gasoline engine (range extender) is activated to provide the energy required to propel the vehicle. As part of the continuing development of this vehicle, MAHLE Powertrain has logged vehicle data in real world driving situations with the aim of understanding the actual usage a REEV under non-laboratory test conditions. The vehicle is instrumented with a data acquisition system to measure physical parameters, for example coolant temperatures, as well as CAN-based data from the engine and vehicle management systems. The logged data has been analysed, using in-house tools, to establish the effect of environmental factors such as ambient temperature, human behavioural characteristics and variation in usage patterns on the efficiency and operational behaviour of the REEV system as a whole.
Technical Paper
2014-09-30
Anil Kumar Cherukuri
Vehicle light-weighting of late has gained a lot of importance across the automotive industry. With the developed nations like the U.S. setting stringent fuel economy targets of 54.5 mpg by 2025, the car industry's R&D is taking light weighting to a whole new level, besides improving engine efficiency. The commercial vehicles on the other hand are also gradually catching up when it comes to using alternate material for weight reduction. This paper will discuss light-weighting in the context of buses though. Vehicle weight is directly related to fuel consumption, a lighter bus takes less energy to move which improves fuel consumption and lowers the operating cost of vehicles that do a huge number of miles over their lifetime. There are certainly many ways to achieve light weight within the strength and safety requirements, Common ones are to completely replace the existing structure material with higher yield strength material with a possible reduction in section thickness. The other is to selectively replace conventional steel at specific areas.
Technical Paper
2014-09-30
Haoting Wang, Tieping Lin, Xiayi Yuan, Qi Zhang
Three dimensional, steady state computational fluid dynamics (CFD) simulations of flow around a generic pickup truck are performed to optimize the aerodynamic performance of a pickup truck model. Detailed comparison between the data of the CFD model and the experiment are made. By using deformation techniques, surrogate models and optimization methods, the drag is reduced. Four design variables are used for deformation: the cabin height, bed height, ground clearance and bed length. The optimization is single objective: minimizing the drag coefficient. A response surface model is built to reduce the sampling points for optimization, and the simulation time is reduced accordingly. Results show that the design variables are not fully independent with each other, and by proper combinations of the variable change, the drag coefficient of the pickup truck model can be reduced effectively. In this study, the drag coefficient reduced about 9.7% through optimization algorithm. The results also show that the single tailgate itself is not always profitable for drag reduction.
Technical Paper
2014-09-30
Vladimir V. Vantsevich, Jeremy P. Gray, Dennis Murphy
Through inverse dynamics-based modeling and computer simulations for a 6x6 unmanned ground vehicle in stochastic terrain conditions, this paper analytically presents a coupled impact of different driveline system configurations and a suspension design on vehicle dynamics, including vehicle mobility and energy efficiency. A new approach in this research work involves an estimation of each axle contribution to the level of potential mobility loss/increase and/or energy consumption increase/reduction. As it is shown, the drive axles of the vehicle interfere with the vehicle’s dynamics through the distribution of the wheel’s normal reactions and wheel torques. The interference causes the dynamics of the independent systems to become operationally coupled/fused, and thus diminishes the vehicle’s mobility and energy efficiency. The analysis is achieved by the use on new mobility indices and energy efficiency indices which are functionally coupled/fused. Four possible scenarios are considered to trade between mobility and energy efficiency improvements by re-distributing power between the drive axles in severe/extreme terrain conditions, including poor mu-conditions, and high longitudinal and lateral slopes.
Technical Paper
2014-09-30
Ashok Patidar, Shivdayal Prasad, Umashanker Gupta, Mohan Subbarao
In today's competitive world, vehicle with light weighting is the most focused area. Vehicle light weighting can be done either by using light weight materials or by reducing the size of the existing components. In present paper later approach of vehicle light weighting is followed. It will help in packaging and reduce weight will add benefit to FE too. Scope for light weighting is identified in exhaust system where muffler volume is optimized using CFD commercial tool FLUENT. The back pressure, exhaust gas temperature, sound noise level & sound quality are chosen as design verification targets. The muffler volume is reduced by 15% resultant system become 15% compact with 2% lighter weight. CFD results are well correlated with physical test results on both the existing and optimized design results. Detailed design guideline and simulation process of exhaust system is explained in this paper.
Technical Paper
2014-09-30
Brian R. McAuliffe, Leanna Belluz, Marc Belzile
Terrestrial winds play an important role in affecting the aerodynamics of road vehicles. Of increasing importance is the effect of the unsteady turbulence structure of these winds and their influence on the process of optimizing aerodynamic performance to reduce fuel consumption. In an effort to predict better the aerodynamic performance of heavy-duty vehicles and various drag reduction technologies, a study was undertaken to measure the turbulent wind characteristics experienced by heavy-duty vehicles on the road. To measure the winds experienced on the road, a sport utility vehicle (SUV) was outfitted with an array of four fast-response pressure probes that could be arranged in vertical or horizontal rake configurations that provided measurements up to 4.0 m from the ground and spanning a width of 2.4 m. To characterize the influence of the proximity of the vehicle on the pressure signals of the probes, the SUV and its measurements system was calibrated in a large wind tunnel. On-road measurements of the turbulence intensities, turbulence length scales, wind spectra, and spatial correlations were performed.
Technical Paper
2014-09-30
Yiting Kang, Subhash Rakheja, Wenming Zhang
Different types of axle suspension systems have evolved for large size mining trucks to achieve improved attenuation of terrain-induced whole-body vibration (WBV) transmitted to the operator and to attain higher operating speeds. The hydro-pneumatic struts are increasingly being used together with different linkage configurations, which could yield widely different kinematic and dynamic properties and thereby the ride and handling performance of the vehicle. This paper presents comprehensive analyses of the different independent front suspension linkages that have been implemented in various off-road vehicles, namely a composite linkage Macpherson strut type suspension (CLT), a candle type suspension (CT), a longitudinal arm type suspension (LAT), and a double wishbone type suspension (DWT). The relative performance analyses are evaluated on the basis of handling dynamics of a 190 tons mining truck. The kinematic variations in camber, caster, inclination angle, toe-in and horizontal wheel center displacements of different linkage suspensions are synthesized via wheel bounce excitations in the MapleSim platform.
Technical Paper
2014-09-30
Youhanna William, Walid Oraby, Sameh Metwally
When driving a vehicle on the road, the driver has to compensate continuously for small directional deviations from the desired course due to disturbances such as crosswinds and road irregularities leading to unintended path deviation. With higher and larger side area such as buses and trucks, the influence of crosswind on the vehicle lateral dynamics behavior is much higher and the vehicle becomes more sensitive to side wind excitations. The study presents a practical theoretical method to judge the aerodynamic response of buses in the early design steps based on both aerodynamic and design parameters. A constant longitudinal velocity 2-DOF vehicle lateral dynamics model is used to investigate a bus lateral response under nine different wind gusts excitations. An accurate validated 3-D CFD simulation model of the bus shape results is integrated with carefully chosen design parameters data of a real bus chassis and body to obtain vehicle lateral dynamic response to the prescribed excitations.
Technical Paper
2014-09-30
Mithun Shetty, Marius-Dorin Surcel
The forestry trucking industry is a major consumer of diesel fuel, and will be into the foreseeable future. One way to achieve fuel savings would be to reduce aerodynamic drag. Currently, aerodynamic improvements for forestry trailer configurations such as logging trailers are not fully understood and more research in this area is required. In most cases, logging trucks on their return trips are usually travelling in unloaded conditions with upright stakes, which add drag. CFD and wind tunnel testing suggested a drag reduction of up to 35% with no upright stakes, which corresponds to 17% in fuel savings in unloaded conditions. One of the proposed fuel reduction concepts was therefore to have foldable bunks so that the bunks or stakes could fold down into a horizontal position while travelling empty. The fuel savings were confirmed with track testing based on the SAE J1321 standard, which compared the fuel consumption of a vehicle with stakes in the horizontal position and a vehicle with stakes in the vertical position.
Technical Paper
2014-09-30
Michael S. Barton, David Corson, John Quigley, Babak Emami, Tanuj Kush
In this work, the multi-physics problem arising from fluid sloshing within a tanker truck undergoing acceleration is investigated through the use of bi-directional coupling between AcuSolve and MotionSolve. This application represents a challenging test case for simulation technology within the design of commercial vehicles. Computer aided engineering is playing a more predominant role in the design process for commercial and passenger vehicles. Better understanding the real time loading and responses on a vehicle during intended (or unintended) use can result in improved design and reduced cost over traditional assumptions. Sloshing of liquid within the cargo tank of a commercial tanker truck results in increased loading on the vehicle's suspension when undergoing different types of acceleration maneuvers. The change in loading can have a significant effect on the design of the vehicles suspension components and braking components. The ability to investigate the fully coupled behavior of the mechanical and fluid systems is a key technology to enable improved designs for these types of applications.
Technical Paper
2014-09-30
Colin Britcher, Wael Mokhtar, Stephen Way
Commercial vehicle design, as well as associated aerodynamic test procedures, acknowledge the fact that many of these vehicles will operate in strong crosswind conditions for a significant fraction of their operational life. For example, the SAE "wind averaged" drag coefficient develops a weighted average CD based on operation at representative speeds in representative winds from arbitrary directions. Wind tunnel testing at a representative road speed over a range of yaw angles of +-15° is sufficient to populate the SAE equation. However, wind tunnel tests of commercial vehicles are often compromised due to the physical size of the model or other factors, leading to various concerns. An on-road crosswind develops a deep atmospheric boundary layer profile. The vehicle's road speed results in the relative velocity field at the vehicle being strongly curved. A curved flow field is practically impossible to generate in a wind tunnel with a substantial mean velocity, although some yacht sail testing is carried out at in curved flow facilities at much lower velocities.
Technical Paper
2014-09-30
Jouke Van der Krieke, Gandert Van Raemdonck
Improving aerodynamic quality, i.e. reducing drag, of semi-trailers will contribute largely to reduce the fuel consumption and the emissions of harmful gases of heavy duty vehicles. In the recent past WABCO developed an aerodynamically shaped skirt, called SideWing, for a European tractor semi-trailer configuration. This solution proved its efficiency during wind tunnel experiments, dedicated track testing and operational testing on public roads. In the Netherlands one is allowed to drive with a longer vehicle combination having a length of 25m, instead of 16.5m for the standard length. This longer combination has a tractor, a semi-trailer and a drawbar trailer. The semi-trailer is equipped with SideWings, while the drawbar trailer has regular skirts. Together with the fleet operator a test was conducted during operational activities to determine the fuel savings of the SideWings with the skirts on this particular vehicle combination. This fuel saving test was conducted with only one vehicle for a total period of fifteen months.
Technical Paper
2014-09-30
Helena Martini, Peter Gullberg, Lennart Lofdahl
Nowadays, much focus for the vehicle manufacturers is put on improving the energy efficiency of their products. The aerodynamic drag constitutes one major part of the total driving resistance for a vehicle driving at higher speeds. In fact, above approximately 80km/h the aerodynamic drag is the dominating resistance acting on a truck. Hence the importance of reducing this resistance is significant. Cooling drag is one part of the total aerodynamic drag, which arises from air flowing through the heat exchangers and the irregular underhood area. When using Computational Fluid Dynamics (CFD) in the development process it is of great importance to ensure that the methods used are accurately capturing the physics of the flow. This paper deals with comparative studies between CFD and wind tunnel tests. In this paper, two comparative studies are presented. One is a comparison between cooling performance simulations and climate wind tunnel measurements; the other study is a comparison between external aerodynamics CFD simulations and wind tunnel measurements.
Technical Paper
2014-09-30
Jeff Smith, Rick Mihelic, Brandon Gifford, Matthew Ellis
On-highway tractor-trailer vehicles operate in a complex aerodynamic environment that includes influences of surrounding vehicles. Typical aerodynamic analyses and testing of single vehicles on test track, in wind tunnel or in CFD do not account for these real world effects. However, it is possible with simulation and on-road testing to evaluate these aerodynamic interactions. CFD and physical testing of multiple vehicle interactions show that traffic interactions can impact the overall drag of leading and trailing vehicles. This paper will discuss results found in evaluating the effects of separation distances on tractor-trailer aerodynamics in on-road and CFD evaluations using a time-accurate Lattice Boltzmann Method based approach and the ramifications for improving real world prediction versus controlled single vehicle testing.
Technical Paper
2014-09-30
Michael P. Lammert, Adam Duran, Jeremy Diez, Kevin Burton, Alex Nicholson
The objective of this research project was to compare fuel economy results of two class 8 tractor trailer combinations platooned together to a standalone tractor trailer combination. A series of twelve modified SAE Type II J1321 fuel economy track tests were used to document fuel economy performance of two platooned vehicles and a baseline vehicle at steady state speeds ranging from 55 mph to 70 mph, from a 20 ft following gap to 75 ft gap and at 65,000 lbs and 80,000 lbs as well as a variable speed platooned test. Additionally, coast down testing was performed on the vehicles in isolation and in platoon formation to quantify aerodynamic impacts of the platoon formation. All tractors involved had EPA Smartway compliant aerodynamics packages and trailers were equipped with side skirts. Testing took place at Uvalde Proving Grounds near San Antonio Texas funded by the Department of Energy (DOE) and managed by the National Renewable Energy Laboratory (NREL). Effects of vehicle speed and following gap on fuel economy were analyzed as well as effects on engine cooling and SCR aftertreatment performance.
Technical Paper
2014-09-30
Marc Ratzel, Warren Dias
Multiple engineering disciplines are considered in the development process of modern vehicles. This includes disciplines such as aerodynamics and structural dynamics. Often, these disciplines are applied in isolation, that is, without the consideration of interactions between disciplines. But in order to accurately represent the physical environment in which these designs and vehicles operate, it becomes important to consider the interaction effects. Interaction effects can be considered by including the effects of the different disciplines in a sequential manner, such as, determining the aerodynamic loads with a computational fluid dynamics (CFD) solver and then using the computed forces as boundary conditions in a structural analysis solver to determine displacements and stresses. However, for certain applications where this sequential modeling approach is not representative, the multiple disciplines can be analyzed in a co-simulation environment. An example of this would be the fluttering of an automotive hood under driving conditions.
Technical Paper
2014-09-30
Shaoyun Sun, Yin-ping Chang, Xinyu Wang, Qiang Fu, Kelong Lu, Zuofeng Pan, Bo Li, Heinz Friz
A big challenge for the aerodynamic optimization of trucks is the limited availability of wind tunnels for testing full scale trucks. FAW wants to introduce a development process which is mainly based on CFD simulation in combination with some limited amount of wind tunnel testing. While accuracy and maturity of CFD simulation for truck aerodynamics has been demonstrated in recent years, a complete validation is still required before committing to a particular process. The CFD tools involved in this validation are Star CCM+ and PowerFLOW. Since there is currently no wind tunnel available in China for the testing of full scale trucks, a 70% scale model is built for testing in the Shanghai Automotive Wind Tunnel Center. Drag and surface pressures are measured for providing a good basis for comparison to the simulation results. The simulations are performed for the scale model geometry as well as for the full scale geometry of the fully detailed truck. As a completion of this validation study a test of the full scale truck with a shortened trailer in a suitable wind tunnel in Europe is planned as future work.
Technical Paper
2014-09-30
Dhiraj Dashrat Salvi
ABSTRACT- Braking system is having a key importance in vehicle safety & handling stability. In this research paper I had developed a circuit model of Anti-lock braking system where the operating medium is hydra-pneumatic. A solenoid operated modulator valve consisting two 2/2 valves is connected in line with the air cylinder & hydraulic master cylinder assembly. Using methodology of response time calibration time taken to modulate hydraulic pressure w.r.t pneumatic pressure is evaluated. The signal input to the modulator valve is given by the Electronic controlled input (ECU). All results obtained is exported to an excel file using Data Acquisition software with pressure myograph system. It gives easy and intuitive readings based on the signal programmed from ECU for various inputs (i.e. ramp, step) .The signal are programmed for various inputs in order to check the fidelity of the circuit. These readings are easily customized to get the optimum graphs. The response time evaluated from the calibrated data is compared with benchmark or standard set by CMVR to meet the regulation.
Technical Paper
2014-09-30
Sivanandi Rajadurai, Prakash Krishnan, Naveen Sridharan, Manimaran Sethuramasubramaniyam
Canning is the process of mounting the support mat & substrate into the shell. Canning is a very important aspect in the catalyst converter design, especially with the current trend of using thinner wall and ultra-thin wall substrates. Considering the reduced isostatic and shear strengths of thin and ultra thin wall substrates, conventional canning technique will reduce canning durability where the mat or the substrate or the shell may be damaged. This brings into requirement a controlled canning process which shall not disturb the canning durability. The paper shall explain an established controlled canning process developed at a very low investment yet with effective outputs using a DOE methodology for choosing the best suited practices for the respective parts for canning. The outputs were cross verified using push out test and GBD verification using destructive methodology and the results obtained were competitive.
Technical Paper
2014-09-30
Sivanandi Rajadurai, Guru Prasad Mani, Sundaravadivelu M, Kavin Raja
Simulation’s drive towards reality boundary conditions is a toughest challenge. Experience has shown that often the most significant source of error in thermal and dynamic analyses is associated within specified boundary conditions. Typically, validating the system by considering both thermal and dynamic loads with predefined assumptions is time consuming and inconclusive when confronted to reality boundary conditions. Thus, solution comes in unique way of combining thermal and dynamic loads with specified boundary conditions will convey computational results closer to real scenario. As a consequence, strain concentrated regions due to thermal expansion are aggregated more, when coupled with dynamic loading. The stress generated by the coupled analyses will proves to be critical in concerning the durability issue of the hot end system. These conditions were evaluated by a finite elements model through a linear and non-linear approach, which had its results summarized.
Technical Paper
2014-09-30
Shaoyun Sun, Yin-ping Chang, Qiang Fu, Jing Zhao, Long Ma, Shijie Fan, Bo Li, Andrea Shestopalov, Paul Stewart, Heinz Friz
In the development of an FAW SUV, one of the goals is to achieve a state of the art drag level. In order to achieve such an aggressive target, feedback from aerodynamics has to be included in the early stage of the design decision process. The aerodynamic performance evaluation and improvement is mostly based on CFD simulation in combination with some wind tunnel testing for validation of the simulation results. As a first step in this process, a fully detailed simulation model is built. The styling surface is combined with engine room and underbody detailed geometry from a similar size existing vehicle. From a detailed analysis of the flow field potential areas for improvement are identified and five design parameters for modifying overall shape features of the upper body are derived. In a second step, a response surface method involving DOE and adaptive sampling techniques is applied for characterizing the effects of the design changes. The characterization is followed by an optimization step to find the best possible drag improvement from these design changes.
Technical Paper
2014-09-30
William Bradford Bartow, Andres C. Moreyra, Trevor Hirst, Gregory H. Woyczynski, Alexis lefebvre, Gecheng Zha
This paper experimentally investigates the detailed flow field of base drag reduction method using passive jet boat-tail (JBT) with 3D PIV measurement in wind tunnel testing. JBT is a new method recently developed by Zha et al to reduce vehicle base drag using passive jet instead of a solid botatail. It has the advantage of no blockage in the base area, which is important for vehicle loading/unloading and is necessary for vehicle rear view mirrors that can not permit any visibility blockage. The wind tunnel experiment indicates that the JBT significantly reduces the wake width and depth(Fig. 1), and thus the base drag. The unsteady wake flaps up and down and left and right. The hypothesis is that the wake flapping transfers the energy to the coherent structures caused by the jet, and then further energizes the base flow region with base pressure increased. The wake profile area at 1.5 length downstream is reduced by about 40%.The 3D PIV measurement found that the jet creates a large circumferential gradient of the flow field, which enhances the entrainment and energy transfer.
Viewing 1 to 30 of 17669