Automobile Aerodynamic Drag on the Road Compared With Wind Tunnel Tests

1981 ◽  
Author(s):  
A. Morelli ◽  
P. Nuccio ◽  
A. Visconti
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Drag ◽  
Wind Tunnel Tests ◽  
The Road ◽  
On The Road

scholarly journals Vehicle Ride Height Change Due To Radial Expansion Of Tires

2015 ◽  
Vol 13 (2) ◽  
pp. 22-27
Author(s):  
Ondřej Čavoj ◽  
Ondřej Blaťák ◽  
Petr Hejtmánek ◽  
Jan Vančura
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Drag ◽  
Vertical Displacement ◽  
Radial Expansion ◽  
Ride Height ◽  
The Road ◽  
Vehicle Aerodynamics ◽  
Height Change ◽  
On The Road ◽  
Aerodynamic Lift

Abstract In general, tire deformations caused by wheel rotation are not taken into account when developing vehicle aerodynamics. On the road the tires radially expand as speed increases, which affects the actual ride height of a vehicle. In turn this often increases the real aerodynamic drag compared to values obtained using CFD or a wind tunnel as the mass flow across the relatively rough underbody increases with ground clearance. In this study, on-road ride heights were measured while running a vehicle in a straight line with fixed velocity whilst the aerodynamic lift of the vehicle was determined in a wind tunnel. Subsequently, the relationships between ride height and axle load were obtained by loading the vehicle at standstill with ballast. By comparing the ride heights at high and very low velocities with expected vertical displacement caused purely by aerodynamic lift force as computed according to the ride height - axle load equations, the ride height change due to tire radial expansion was determined.

scholarly journals Wind Tunnel Tests to Reduce Aerodynamic Drag of Trains by Smoothing the Under-floor Construction

2001 ◽  
Vol 42 (2) ◽  
pp. 94-97 ◽  
Author(s):  
Atsushi IDO ◽  
Yoshihiko KONDO ◽  
Tsuyoshi MATSUMURA ◽  
Minoru SUZUKI ◽  
Tatsuo MAEDA
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Drag ◽  
Wind Tunnel Tests

A First Investigation of Truck Drivers’ Preferences and Behaviors using a Prototype Cooperative Adaptive Cruise Control System

2018 ◽  
Vol 2672 (34) ◽  
pp. 39-48 ◽  
Author(s):  
Shiyan Yang ◽  
Steven E. Shladover ◽  
Xiao-Yun Lu ◽  
Hani Ramezani ◽  
Aravind Kailas ◽  
...  
Keyword(s):  
Adaptive Cruise Control ◽  
Aerodynamic Drag ◽  
Truck Drivers ◽  
Cruise Control ◽  
Fuel Savings ◽  
The Road ◽  
Cooperative Adaptive Cruise Control ◽  
And Behaviors ◽  
On The Road ◽  
And Performance

Cooperative adaptive cruise control (CACC) is a driver-assist technology that uses vehicle-to-vehicle wireless communication to realize faster braking responses in following vehicles and shorter headways compared with adaptive cruise control. This technology not only enhances road safety, but also offers fuel savings benefits as a result of reduced aerodynamic drag. The amount of fuel savings is dictated by the following distances and the driving speeds. So, the overarching goal of this work is to explore driving preferences and behaviors when following in “CACC mode,” an area that remains largely unexplored. While in CACC mode, the brake and throttle actions are automated. A human factors study was conducted to investigate truck drivers’ experiences and performance using CACC at shorter-than-normal vehicle following time gaps. “On-the-road” experiments were conducted by recruiting drivers from commercial fleets to operate the second and third trucks in a three-truck CACC string. The driving route spanned 160 miles on freeways in Northern California and five different time gaps between 0.6 and 1.8 seconds were tested. Factors such as cut-ins by other vehicles, road grades, and traffic conditions were found to influence the drivers’ opinions about use of CACC. The findings presented in this paper provide insights into the factors that will influence driver reactions to the deployment of CACC in their truck fleets.

Aeroacoustic Measurements in Turbulent Flow on the Road and in the Wind Tunnel

2007 ◽  
Author(s):  
N. Lindener ◽  
H. Miehling ◽  
A. Cogotti ◽  
F. Cogotti ◽  
M. Maffei
Keyword(s):  
Wind Tunnel ◽  
Turbulent Flow ◽  
The Road ◽  
On The Road

Modernization of the Trailer for Tyre/Road Rolling Resistance Measurements

2011 ◽  
Vol 490 ◽  
pp. 179-186 ◽  
Author(s):  
Ryszard Woźniak ◽  
Stanislaw Taryma ◽  
Grzegorz Ronowski
Keyword(s):  
Laboratory Tests ◽  
Aerodynamic Drag ◽  
Rolling Resistance ◽  
Test System ◽  
Inertia Force ◽  
The Road ◽  
University Of Technology ◽  
On The Road ◽  
The Impact ◽  
Resistance Tests

In the article the ways of defining tyre rolling resistance are presented. The advantages of the laboratory tests of tyre/road rolling resistance and the advantages and the disadvantages of on the road tyre/road rolling resistance tests are described. The description of the special trailer used for tyre/road rolling resistance measurements designed and constructed in Faculty of Mechanical Engineering at Gdansk University of Technology is presented also. The trailer during it’s modernisation was equipped with special test systems which compensate the impact of disturbance factors such as: aerodynamic drag and inertia force acting on the tested tyre, slope of the road, tilt of the trailer and vibrations of the measuring arm. This article contains the description of only one compensation system applied in the measuring trailer which eliminates the aerodynamic drag. The conclusions which came from the measurements performed using this compensation test system are included.

Drag Reduction on SUVs and Trucks by Wake Control

2008 ◽  
Author(s):  
Amarddin Z. Maazouddin ◽  
Dongmei Zhou
Keyword(s):  
Aerodynamic Drag ◽  
Bluff Bodies ◽  
Road Vehicles ◽  
The Road ◽  
Pressure Drag ◽  
Flow Features ◽  
Commercial Software Package ◽  
On The Road ◽  
Lift And Drag ◽  
Work Done

Road vehicles such as SUVs or pickup trucks are described as bluff bodies. When the air flow passes over the road vehicles the flow will separate at the rear of the vehicle, forming a large low pressure turbulent wake region behind the vehicle. The formed pressure drag posts resistance on the road vehicles and thus increases the work done by the engine to propel the vehicle. The purpose of this paper is to present the development and design of drag reducing devices for SUVs by studying the SUV’s aerodynamics. Numerical simulations using commercial software package — FLUENT were performed in order to study the aerodynamics behind the vehicles. A computer model of the Ahmed Vehicle Model was selected as a benchmark test. This Ahmed Model is a simple geometric body that retains major flow features where most part of the drag is concentrated. Seven different spoiler designs for the SUV have been studied. Their results for the SUV’s aerodynamics have been presented through velocity vectors, pressure contours, and aerodynamic lift and drag plots. One spoiler design was found to be able to reduce aerodynamic drag and others were found to be able to reduce the lift.

scholarly journals Impact of wheel rotation on the aerodynamic drag of a time trial cyclist

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Fabio Malizia ◽  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Aerodynamic Drag ◽  
Front Wheel ◽  
Wind Tunnel Tests ◽  
Wheel Rotation ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Drag Area

AbstractAerodynamic drag is the main resistive force in cycling at high speeds and on flat terrain. In wind tunnel tests or computational fluid dynamics simulations, the aerodynamic drag of cycling wheels is often investigated isolated from the rest of the bicycle, and sometimes in static rather than rotating conditions. It is not yet clear how these testing and simulating conditions influence the wheel aerodynamic performance and how the inclusion of wheel rotation influences the overall measured or computed cyclist drag. This study presents computational fluid dynamics simulations, validated with wind tunnel tests, that indicate that an isolated static spoked front wheel has a 2.2% larger drag area than the same wheel when rotating, and that a non-isolated static spoked front wheel has a 7.1% larger drag area than its rotating counterpart. However, rotating wheels are also subjected to the rotational moment, which increases the total power required to rotate and translate the wheel compared to static conditions where only translation is considered. The interaction with the bicycle frame and forks lowers the drag area of the front wheel by 8.8% for static and by 12.9% for the rotating condition, compared to the drag area of the isolated wheels. A different flow behavior is also found for static versus rotating wheels: large low-pressure regions develop from the hub for rotating wheels, together with a lower streamwise velocity region inside the circumference of the wheel compared to static wheels. The results are intended to help in the selection of testing/simulating methodologies for cycling spoked wheels.

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