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Multidisciplinary Investigation of Truck Platooning

Altair-Bastian Schnepf, Christian Kehrer, Christoph Maeurer
  • Technical Paper
  • 2020-37-0028
To be published on 2020-06-23 by SAE International in United States
In the age of environmental challenges and with it, the demand for increasing energy efficiency of commercial vehicles, truck platooning is discussed as a promising approach. The idea is several trucks forming an automated convoy – with the lead truck sending out acceleration, braking and steering signals for the following trucks to react accordingly. The benefits address fuel savings, traffic capacity, safety requirements and convenience. In our study, we will motivate why platooning requires a multidisciplinary approach in the sense of connecting different modeling and simulation methods. The simulation topics covered are aerodynamic analysis, vehicle-to-vehicle (V2V) communication, radar antenna placement and virtual drive cycle test for the energetic evaluation of a truck platoon in comparison to a single truck. Aerodynamic analyses are conducted using a transient Lattice Boltzmann approach on GPUs capturing the complex vehicle wake interactions for different platooning distances with acceptable computational effort. Thereby, a generic truck convoy, consisting of three vehicles, is considered for distance intervals between 7 and 40 meters. From these computations for each vehicle look-up-tables are derived for interpolation…
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A Study on the Effect of Debris Location on a Double Element Wing in Ground Effect

Loughborough University-Tom Marsh, Graham Hodgson, Andrew Garmory, Dipesh Patel
  • Technical Paper
  • 2020-01-0693
To be published on 2020-04-14 by SAE International in United States
Multi-element front wings are essential in numerous motorsport series, such as Formula 1, for the generation of downforce and control of the onset flows to other surfaces and cooling systems. Rubber tyre debris from the soft compounds used in such series can become attached to the wing, reducing downforce, increasing drag and altering the wake characteristics of the wing. This work studies, through force balance and Particle Image Velocimetry (PIV) measurements, the effect a piece of debris has on an inverted double element wing in ground effect. The debris is modelled using a hard-setting putty and is located at different span and chord-wise positions around the wing. The sensitivity to location is studied and the effect on the wake analysed using PIV measurements. The largest effect on downforce was observed when the debris was located on the underside of the wing towards the endplates. The wake was most effected when the debris was located closest to the gap, generating a large fluctuating wake with a significantly different path to the baseline case.
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Utilization of Vehicle Connectivity for Improved Energy Consumption of a Speed Harmonized Cohort of Vehicles

Michigan Technological University-Christopher Morgan, Darrell Robinette, Pruthwiraj Santhosh, John Bloom-Edmonds
  • Technical Paper
  • 2020-01-0587
To be published on 2020-04-14 by SAE International in United States
Improving vehicle response through advanced knowledge of traffic behavior can lead to large improvements in energy consumption for the single isolated vehicle. This energy savings across multiple vehicles can even be larger if they travel together as a cohort in harmonization. Additionally, if the vehicles have enough information about their immediate path of travel, and other vehicles’ in that path (and their respective critical forward-looking information), they can safely drive close enough to each other to share aerodynamic load. These energy savings can be upwards of multiple percentage points, and are dependent on several criteria. This analysis looks at criteria that contributes to energy savings for a cohort of vehicles in synchronous motion, as well as describes a study that allows for better understanding of the potential benefits of different types of cohorted vehicles in different platoon arrangements. The basis of this study is a precursor to developing a connected vehicle application that safely allows for fully controlled platooning on open highway for multi-destination vehicles.In this study, a set of light duty plug-in hybrid electric…
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Investigation of Transient Aerodynamic Effects on Public Roads in Comparison to Individual Driving Situations on a Test Site

FKFS-Felix Wittmeier, Andreas Wagner, Jochen Wiedemann
German Aerospace Center (DLR)-Henning Wilhelmi, Andreas Dillmann
  • Technical Paper
  • 2020-01-0670
To be published on 2020-04-14 by SAE International in United States
Natural wind, roadside obstacles, terrain roughness, and traffic influence the incident flow of a vehicle driven on public roads. These transient on-road conditions differ from the idealized statistical steady-state flow environment utilized in CFD simulations and wind tunnel experiments. To understand these transient on-road conditions better, measurements were performed on German public highways and on a test site. A compact car was equipped with a measurement system that is capable of determining the transient airflow around the vehicle and the vehicle’s actual driving state. This vehicle was driven several times on a predefined 200 km long route to investigate different traffic densities on public highways in southern Germany. During the tests the transient incident flow and pressure distribution on the vehicle surface were measured. With the same test vehicle, individual driving situations were recreated on a test site under weather conditions similar to those of the tests on public roads. This paper presents a comparison of the aerodynamic characteristics measured on public highways and on the test site. Two driving situations were examined at the…
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Optimization of the Aerodynamic Lift and Drag of LYNK&CO 03+ with Simulation and Wind Tunnel Test

Dassault Systemes(Shanghai) Information Technology Co.-Weiliang Xie, Bo Li, Xiaowei Zhao
Geely Automobile Research Institute-Qian Feng, Biaoneng Luo, Huixiang Zhang, Hong Peng, Zhenying Zhu, Zhi Ding, Ling Zhu
  • Technical Paper
  • 2020-01-0672
To be published on 2020-04-14 by SAE International in United States
Based on the first sedan of the LYNK&CO brand from Geely, the high-performance configuration equipped with an additional aerodynamic package was developed. The aerodynamic package including front wheel deflectors, front lip, side skirts, rear spoiler, and rear diffuser, was required to be upgraded to generate enough aerodynamic downforce for better handling stability, without compromising the aerodynamic drag of the vehicle too much to keep a low fuel consumption.Starting from the baseline configuration of the aerodynamics package provided by the design studio, the components were optimized for aerodynamic drag and lift using the simulation approach with PowerFLOW in combination with a design space exploration method. As a result, the targets for the aerodynamic coefficients of the vehicle and in particular a good trade-off between lift and drag were achieved. Wind tunnel testing was involved to calibrate the simulation results at the beginning and to validate the optimized design at the end of the aerodynamic development. A consistently good agreement between the simulation and experiment was achieved.
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Large Scale Multi-Disciplinary Optimization and Long-Term Drive Cycle Simulation

Dassault Systemes-Mark Malinovskiy, Andrew Hermetet, Christopher Lee
General Motors LLC-Shailendra Kaushik
  • Technical Paper
  • 2020-01-1049
To be published on 2020-04-14 by SAE International in United States
Market demands for increased fuel economy and reduced emissions are placing higher aerodynamic and thermal analysis demands on vehicle designers and engineers. These analyses are usually carried out by different engineering groups in different parts of the design cycle. Design changes required to improve vehicle aerodynamics often come at the price of part thermal performance and vice versa. These design changes are frequently a fix for performance issues at a single performance point such as peak power, peak torque, or highway cruise. In this paper, the motivation for a holistic approach in the form of multi-disciplinary optimization (MDO) early in the design process is presented. Using a Response-surface Informed Transient Thermal Model (RITThM) a vehicle's thermal performance through a drive cycle is predicted and correlated to physical testing for validation. Furthermore, an MDO using RITThM is demonstrated with tradeoffs and important trends identified and described along with optimal design points. Potential sources of error, areas for improvement, and potential applications of an MDO using RITThM are presented.
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Impact of Rim Orientation on Road Vehicles Aerodynamics Simulations

Graz University of Technology-Wolfgang von der Linden, Günter Brenn
Magna Steyr Fahrzeugtechnik AG & Co KG-Gernot Bukovnik
  • Technical Paper
  • 2020-01-0674
To be published on 2020-04-14 by SAE International in United States
Aerodynamic CFD simulations in the automotive industry based on the steady-state RANS (Reynolds-averaged Navier–Stokes) approach typically utilize approximate numerical methods to account for rotating wheels. In these methods, the computational mesh representing the rim geometry remains stationary, and the influence of the wheel rotation on the air flow is modelled. As the rims are considered only in one fixed rotational position (chosen arbitrarily in most cases), the effects of the rim orientation on the aerodynamic simulation results are disregarded and remain unquantified. This paper presents a numerical sensitivity study to examine the impact of the rim orientation position on the aerodynamic parameters of a detailed production vehicle. The simulations are based on the steady-state RANS approach. These investigations are carried out for three rim geometries, and for simulation cases with stationary and rotating wheels for comparison, where the Moving Wall (MW) and the Moving Reference Frame (MRF) methods, as well as combinations of the two approaches are used to model the wheel rotation. For the test vehicle, alterations in the flow field, and subsequently an…
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Parametric Study of Reduced Span Side Tapering on a Simplified Model with Wheels

Jaguar Land Rover-Adrian Gaylard
Loughborough University-Max Varney, Martin Passmore, Ryan Swakeen
  • Technical Paper
  • 2020-01-0680
To be published on 2020-04-14 by SAE International in United States
Many modern vehicles have blunt rear end geometries for design aesthetics and practicality; however, such vehicles are potentially high drag. The application of tapering; typically applied to an entire edge of the base of the geometry is widely reported as a means of reducing drag, but in many cases, this is not practical on real vehicles. In this study side tapers are applied to only part of the side edge of a simplified automotive geometry, to show the effects of practical implementations of tapers.The paper reports on a parametric study undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor model equipped with wheels. The aerodynamic effect of implementing partial side edge tapers is assessed from a full height taper to a 25% taper in both an upper and lower body configuration. These were investigated using force and moment coefficients, pressure measurements and planar particle image velocimetry (PIV). These geometries showed that the drag reductions are maximised with a 50% span, generating a vertically symmetric wake and less taper drag contribution when compared…
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On Road Fuel Economy Impact by the Aerodynamic Specifications under the Natural Wind

Honda R&D Co., Ltd.-Yasuyuki Onishi, Kenta Ogawa, Jun Sawada, Youji Suwa, Fortunato Nucera
  • Technical Paper
  • 2020-01-0678
To be published on 2020-04-14 by SAE International in United States
According to some papers, the label fuel economy and the actual fuel economy experienced by the customers may exhibit a gap. One of the reasons may stem from the aerodynamic drag variations due to the natural wind. The fuel consumptions are measured on the bench test under the several driving modes by using the road load as input conditions. The road load is measured through the coast down test under less wind ambient conditions as determined by each regulation. The present paper aims to analyze the natural wind specifications encountered by the vehicle on the public road and to operate a comparison between the fuel consumptions and the driving energy. In this paper, the driving energy is calculated by the aerodynamic drag from the natural wind specifications and driving conditions. This driving energy and the fuel consumptions show good correlation. The fuel consumption is obtained from the vehicle ECU data. The driving energy is calculated by the aerodynamic drag and the vehicle driving conditions through the time history data on the road. Aerodynamic drag is…
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Impact of Active-Grille Shutter Position on Vehicle Air-Conditioning System Performance and Energy Consumption in Real World Conditions

FCA Canada Inc.-Shankar Natarajan, Pooya Mirzabeygi
FCA US LLC-Michael Westra, Kumar Srinivasan
  • Technical Paper
  • 2020-01-0947
To be published on 2020-04-14 by SAE International in United States
Active grille shutter (AGS) in a vehicle provides aerodynamic benefit at high vehicle speed by closing the front-end grille opening. At the same time this causes lesser air flow through the cooling module which includes the condenser. This results in higher refrigerant pressure at the compressor outlet. Higher head pressure causes the compressor to work more, thereby possibly negating the aerodynamic benefits towards vehicle power consumption. This paper uses a numerical method to quantify the compressor power consumed in different scenarios and assesses the impact of AGS closure on total vehicle energy consumption. The goal is to analyze the trade-off between the aerodynamic performance and the compressor power consumption at high vehicle speeds and mid-ambient conditions. These so called real world conditions represent highway driving at mid-ambient temperatures where the air-conditioning (AC) load is not heavy. AC system is modeled using 1D methodology and its performance simulated at system level. Net power consumed by the vehicle is computed for different scenarios using a robust comparison methodology. System model is validated against vehicle drive cell test…