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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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Investigation of Transient Aerodynamic Effects on Public Highways 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 can influence the incident flow of a vehicle driven on public roads. These 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 taken on a test site and on German Autobahn, resulting in the characterization of the transient aerodynamic effects around a vehicle. 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 fixed route to investigate different traffic densities on public highways in southern Germany. The tests were conducted under consistent weather conditions and average wind velocities of 2-5 m/s. During the tests the transient incident flow and pressure distribution on the vehicle surface were measured. With the same vehicle, individual driving situations were recreated on a test site. This paper presents a comparison of the aerodynamic characteristics measured by the vehicle during a…
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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, a high performance configuration with the additional aerodynamic package was developed. The aerodynamic package including the front wheel deflector, the front lip, the side skirt, the rear spoiler and the rear diffuser, were upgraded to generate enough aerodynamic downforce for better handing stability, without too much compromising of the aerodynamic drag of the vehicle to keep a low fuel consumption. Simulation approach with PowerFLOW, combined with the design space exploration method were used to optimize both of the aerodynamic lift and drag. Wind tunnel test was also used to firstly calibrate the simulation results and finally to validate the optimized design. The results turn out to be appropriate trade-off between the lift and the drag to meet the aerodynamics requirement, and a consistently good matching between the simulation and test.
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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 power consumed by the vehicle in different scenarios and assesses the impact of AGS closure on 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 high way driving at mid-ambient temperatures where the air-conditioning (AC) load is not heavy. AC system which includes the refrigerant loop and vehicle cabin is modeled using 1D methodology and its performance simulated at system level. AC system performance is analyzed under steady state as well as transient conditions. Power consumption…
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Design Optimization and Aerodynamic Analysis of a Hybrid Blended Wing Body- VTOL Unmanned Aerial Vehicle

Delhi Technological University-Pranav Bahl, Vikas Rastogi, Amit bainsla, Nitin Sharma
  • Technical Paper
  • 2020-01-0472
To be published on 2020-04-14 by SAE International in United States
Unmanned Aerial Vehicles (UAVs) can be effectively used to serve humanitarian relief efforts during environmental disasters. Designing such UAVs presents challenges in optimizing design variables such as maximizing endurance, maneuverability and payload capacity with minimum launch and recovery area. The Blended Wing Body (BWB) is a novel aircraft configuration offering enhanced performance over conventional UAVs. Designing a blended wing configuration UAV takes into account interdependency between aerodynamic performance and stability. Designing BWB is peculiar and is investigated in this paper with a view to achieve an aerodynamically stable and structurally sound configuration. The designed UAV is a hybrid of a tailless blended-wing-body and a tri-copter configuration with two forward tilt motors for transition into cruise flight after vertical take-off and back to multirotor while landing (VTOL-Vertical Take Off and Landing). The BWB is iteratively optimized in XFLR-5 for Dynamic and static stability. The wing design was optimized for aerodynamic and structural fitness in MATLAB using Meta-heuristic optimization methodology based on genetic evolutionary algorithm. The 3D CAD design was conceived on SolidWorks and analyzed in Pressure…
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Optimizing Gear Ratio Selection for Lap Performance

Univ. of Alabama-Robert Frederick
University of Alabama-Brandon Dixon
  • Technical Paper
  • 2020-01-0543
To be published on 2020-04-14 by SAE International in United States
The goal of this paper is to select the optimal gear ratios to determine the best overall lap time for a racing vehicle. Given a discrete set of individual gear ratio and final drive ratio options, the simulation chooses the set of gears and final drive that produce the minimum overall lap time. For example, one vehicle studied in this paper, an F2000 formula car, has 32 ratio choices for four forward gears and a final drive that has three different options. The simulation will iterate through the gear options to find the optimal gear selection for the best lap performance, accounting for various factors that could cause improper selection of gears. The simulation accounts for aerodynamic factors, gear shift time, rolling resistance and tire scrub. All values have been estimated from logged vehicle data, but experimental data can be easily used to help improve the vehicle model. Two vehicles were used in this simulation to compare the different types of racing and how that affects the gear selection. The first vehicle is the F2000…