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Viewing 1 to 30 of 2479
2015-06-22
Event
This session is to present numerical and experimental work pertaining to noise due to flow around the vehicle body, such as flow-induced interior noise, flow over protrusions, sunroofs, windows, noise from ventilation systems, or flow noise in exhaust system. Papers on aerodynamics alone without sound are excluded. Numerical studies may include new models or models based on existing theory as long as they are adequately supported by experimental or theoretical verifications.
2015-06-22
Event
This session is devoted to NVH issues arising within the aeronautical and aerospace industries, such as community noise, aircraft interior noise, aerospace vibro-acoustics, noise prediction, modeling and modal analysis.
2014-10-09
Event
This session will address aerodynamic testing requirements, technologies, facilities and methods with a view toward improving efficiency and reducing emissions of medium and heavy commercial ground vehicles. Papers are solicited that address aerodynamic related corrections, correlations and assessments for various data sources including wind tunnel, and on-track/road testing.
2014-10-09
Event
This session will address aerodynamic testing requirements, technologies, facilities and methods with a view toward improving efficiency and reducing emissions of medium and heavy commercial ground vehicles. Papers are solicited that address aerodynamic related corrections, correlations and assessments for various data sources including wind tunnel, and on-track/road testing.
2014-10-08
Event
This session will address processes, strategies and techniques for the aerodynamic design and development of commercial vehicles and components with a view toward improving efficiency and reducing emissions. This topic includes aerocoustics and aerothermodynamics including underhood and cooling flows. Technical papers on the challenges and limitations of current design studies, tools, methods and processes are desired.
2014-10-08
Event
Aerodynamic drag reduction has been identified as a primary technology for increasing fuel economy and thus improving the economic health of the trucking industry as well as the environmental health of the US. The acceptance of aerodynamics as a major player in trucking efficiency has increased significantly over the past decade and this trend is expected to continue. Position papers on the current status and future role of aerodynamic technology on vehicle and vehicle component design are desired. Proposed papers should focus on the science and engineering challenges including atmospheric effects, trailer aerodynamics, tire and wheel aerodynamics and safety.
2014-10-07
Event
This two hour session will serve as an opening discussion on the growing regulatory environment associated with improving commercial vehicle aerodynamics and methods. Europe, Japan and North America (Canada, U.S. and California) regulatory groups as well as SAE are involved in the development of regulations for aerodynamic test and analysis methods. Industry experts from the EPA, NHTSA, NAS, EMA, NRC and more will discuss their views regarding the challenges and limitations of current and proposed regulatory methods. Don't miss your opportunity to have a face to face question and answer session with this dynamic lineup of speakers.
2014-09-30
Technical Paper
2014-01-2452
Colin Britcher, Wael Mokhtar, Stephen Way
Abstract Aerodynamic testing of heavy commercial vehicles is of increasing interest as demands for dramatically improved fuel economy take hold. Various challenges which compromise the fidelity of wind tunnel simulations must be overcome in order for the full potential of sophisticated aerodynamic treatments to be realized; three are addressed herein. First, a limited number of wind tunnels are available for testing of this class of vehicle at large scales. The authors suggest that facilities developed for large or full-scale testing of race cars may be an important resource. Second, ground simulation in wind tunnels has led to the development of Moving Ground Plane (MGP, aka Rolling Road (RR)) systems of various types. Questions arise as to the behavior of MGP/RR systems with vehicles at large yaw angles. It can actually be deduced that complete simulation of crosswind conditions on an open road in a wind tunnel may be impractical. This is due to the fact that the atmospheric crosswind develops a deep boundary layer profile, such that the resultant inflow seen by the moving vehicle is effectively curved.
2014-09-30
Technical Paper
2014-01-2448
William Bradford Bartow, Andres C. Moreyra, Trevor Hirst, Gregory H. Woyczynski, Alexis Lefebvre, Gecheng Zha
Abstract This study is focused on the detailed experimental investigation of jet boat-tail (JBT) passive flow control bluff body models to reduce the base pressure drag. The JBT technique is employed through an open inlet at the leading edge of the bluff body along with a circumferential jet at the trailing edge in order to energize the base flow using the high kinetic energy flow from freestream. As a consequence, entrainment of the main flow into base flow region is initiated earlier downstream. A reduction in the turbulent fluctuation of the wake can be observed in addition to a decrease of the recirculation region velocity. Using 2D/3C Particle Image Velocimetry (PIV), two models with different inlet sizes are tested. The large flow rate model is designed with an inlet area 4.7 times greater than the other JBT prototype. The wind tunnel experimental results show a substantial reduction in the wake width and depth for the two models, which indicates a significant drag reduction. Moreover, mean velocity vector plots from PIV measurements at the mid-plane location suggest their flow fields differ significantly due to the nature of the passive jets employed.
2014-09-30
Technical Paper
2014-01-2444
Shaoyun Sun, Yin-ping Chang, Xinyu Wang, Qiang Fu, Kelong Lu, Zuofeng Pan, Bo Li, Heinz Friz
Abstract A 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 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. A 70% scale model is built for testing in the Shanghai Automotive Wind Tunnel Center (SAWTC). Drag and surface pressures are measured for providing a good basis for comparison to the simulation results. The simulations are performed for the truck in the open road driving condition as well as in an initial digital model of the aerodynamic wind tunnel of SAWTC. A full size truck is also simulated in the open road driving condition to understand the scaling effect. As a 70% scale model of a heavy truck is seen to be close to the limits of the SAWTC wind tunnel, an attempt is made to understand possible wind tunnel effects by including an approximate geometry of the wind tunnel in the simulations of the scale model.
2014-09-30
Technical Paper
2014-01-2446
Marc Ratzel, Warren Dias
Abstract This paper discusses the behavior of a flexible flap at the rear end of a generic car model under aerodynamic loads. A strong bidirectional coupling between the flap's deflection and the flow field exists which requires this system to be simulated in a coupled fluid-structure manner. A coupled transient aerodynamic and structural simulation is performed for a generic car model with a flexible/deformable flap at the rear end. An automatic workflow is established which generates new flap designs, derived from an initial flap design by applying a mesh deformation technology, and performs the coupled fluid-structure interaction analysis. For each shape variation, the flap's maximum displacement is monitored and used to classify the individual flap designs. This process allows for design of experiment (DOE) studies in an automated manner. Several shape variations of the flap and their impacts on the maximum deflection are investigated. Design changes causing a reduction in the maximum deflection are identified and used in an optimization loop to determine a flap design with minimum displacement.
2014-09-30
Technical Paper
2014-01-2437
Haoting Wang, Tieping Lin, Xiayi Yuan, Qi Zhang
Abstract 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.
2014-09-30
Technical Paper
2014-01-2438
Michael P. Lammert, Adam Duran, Jeremy Diez, Kevin Burton, Alex Nicholson
Abstract This research project evaluates fuel consumption results of two Class 8 tractor-trailer combinations platooned together compared to their standalone fuel consumption. A series of ten modified SAE Type II J1321 fuel consumption track tests were performed to document fuel consumption of two platooned vehicles and a control vehicle at varying steady-state speeds, following distances, and gross vehicle weights (GVWs). The steady-state speeds ranged from 55 mph to 70 mph, the following distances ranged from a 20-ft following distance to a 75-ft following distance, and the GVWs were 65K lbs and 80K lbs. All tractors involved had U.S. Environmental Protection Agency (EPA) SmartWay-compliant aerodynamics packages installed, and the trailers were equipped with side skirts. Effects of vehicle speed, following distance, and GVW on fuel consumption were observed and analyzed. The platooning demonstration system used in this study consisted of radar systems, Dedicated Short-Range Communication (DSRC) vehicle-to-vehicle (V2V) communications, vehicle braking and torque control interface, cameras and driver displays.
2014-09-30
Technical Paper
2014-01-2443
Helena Martini, Peter Gullberg, Lennart Lofdahl
Abstract Nowadays, much focus for vehicle manufacturers is directed towards improving the energy efficiency of their products. The aerodynamic drag constitutes one major part of the total driving resistance for a vehicle travelling 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 apparent. Cooling drag is one part of the total aerodynamic drag, which arises from air flowing through the heat exchangers, and the irregular under-hood 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 chassis dynamometer measurements; the other study is a comparison between external aerodynamics simulations and wind-tunnel measurements.
2014-09-30
Technical Paper
2014-01-2436
Jeff Smith, Rick Mihelic, Brandon Gifford, Matthew Ellis
Abstract 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 computational fluid dynamics (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.
2014-09-30
Technical Paper
2014-01-2450
Jouke Van der Krieke, Gandert Van Raemdonck
Abstract Improving the aerodynamic drag level of semi-trailers will contribute largely to reduce the fuel consumption and the emissions of harmful gases of heavy duty vehicles. The final step in product validation of aerodynamic drag reduction devices is often conducting fuel savings test during operational activities. During an operational test, data is gathered for a period when the vehicle is not equipped with an aerodynamic device and consequently for a period with the device equipped. A simple fuel consumption comparison between the periods does not give the desired accurate result as the operating conditions are different for the control and test period. In an attempt to take these varying conditions into account, the average fuel consumption per ride is modeled as a linear function of several independent variables: the wind conditions, the outside temperature, the humidity, the payload, the road inclination and the presence of the drag reduction device. The coefficients in this linear relationship are determined using a robust linear least squares algorithm.
2014-09-30
Technical Paper
2014-01-2449
Youhanna William, Walid Oraby, Sameh Metwally
Abstract This study presents a practical theoretical method to judge the aerodynamic response of buses in the early design stage based on both aerodynamic and design parameters. A constant longitudinal velocity 2-DOF vehicle lateral dynamics model is used to investigate the lateral response of a bus under nine different wind gusts excitations. An appropriate 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. Vehicle model validity is carried out then, the 2-DOF vehicle lateral dynamics model has been executed in MATLAB Simulink environment with the selected data. Simulation represents the vehicle in a straight ahead path then entered a gusting wind section of the track with a fixed steering wheel. Vehicle response includes lateral deviation (LD), lateral acceleration (LA), yaw angle (YA) and yaw rate (YR). Results showed that in case of 25 m/s wind gust [which corresponds to 45° wind relative yaw angle (βw)], the vehicle Lateral Deviation (LD) maintained about 5 m after 4.5 seconds of entering the wind gust.
2014-09-30
Technical Paper
2014-01-2447
Mithun Shetty, Marius-Dorin Surcel
Abstract The main objective of this study is to reduce the aerodynamic drag of tractor-trailer combinations used in the forest industry. 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 stakes so that the stakes could fold down into a horizontal position while travelling in unloaded conditions. Fuel savings of 15% for a vehicle with stakes in the horizontal position were confirmed with track testing when compared to the fuel consumption of a vehicle with stakes in the vertical position. The coastdown test indicated 28% reduction in drag. The difference in drag reduction between the coastdown test and initial simulation was due to stake size and profile. The simulation was therefore conducted again with the stakes' profile similar to the one used in the track test and the same drag reduction of 28% was obtained.
2014-09-30
Technical Paper
2014-01-2445
Shaoyun Sun, Yin-ping Chang, Qiang Fu, Jing Zhao, Long Ma, Shijie Fan, Bo Li, Andrea Shestopalov, Paul Stewart, Heinz Friz
Abstract 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 verification 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 design of experiments and adaptive sampling techniques are 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.
Viewing 1 to 30 of 2479

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