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.

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

scholarly journals Some Observations on Shape Factors Influencing Aerodynamic Lift on Passenger Cars

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 44
Author(s):  
Jeff Howell ◽  
Steve Windsor ◽  
Martin Passmore
Keyword(s):  
Wind Tunnel ◽  
High Performance ◽  
Aerodynamic Drag ◽  
Small Scale ◽  
Shape Features ◽  
Passenger Cars ◽  
Shape Factors ◽  
Front End ◽  
Factors Influencing ◽  
Aerodynamic Lift

The car aerodynamicist developing passenger cars is primarily interested in reducing aerodynamic drag. Considerably less attention is paid to the lift characteristics except in the case of high-performance cars. Lift, however, can have an effect on both performance and stability, even at moderate speeds. In this paper, the basic shape features which affect lift and the lift distribution, as determined from the axle loads, are examined from wind tunnel tests on various small-scale bodies representing passenger cars. In most cases, the effects of yaw are also considered. The front-end shape is found to have very little effect on overall lift, although it can influence the lift distribution. The shape of the rear end of the car, however, is shown to be highly influential on the lift. The add-on components and other features can have a significant effect on the lift characteristics of real passenger cars and are briefly discussed. The increase in lift at yaw is, surprisingly, almost independent of shape, as shown for the simple bodies. This characteristic is less pronounced on real passenger cars but lift increase at yaw is shown to rise with vehicle length.

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 Aerodynamic integration produces a vehicle shape with a negative drag coefficient

2021 ◽  
Vol 118 (27) ◽  
pp. e2106406118
Author(s):  
Kambiz Salari ◽  
Jason M. Ortega
Keyword(s):  
Aerodynamic Drag ◽  
The United States ◽  
Body Axis ◽  
Heavy Vehicle ◽  
Heavy Vehicles ◽  
Drag Coefficients ◽  
The Road ◽  
On The Road ◽  
Vehicle Shape ◽  
Dynamics Simulations

Negative drag coefficients are normally associated with a vessel outfitted with a sail to extract energy from the wind and propel the vehicle forward. Therefore, the notion of a heavy vehicle, that is, a semi truck, that generates negative aerodynamic drag without a sail or any external appendages may seem implausible, especially given the fact that these vehicles have some of the largest drag coefficients on the road today. However, using both wind tunnel measurements and computational fluid dynamics simulations, we demonstrate aerodynamically integrated vehicle shapes that generate negative body-axis drag in a crosswind as a result of large negative frontal pressures that effectively “pull” the vehicle forward against the wind, much like a sailboat. While negative body-axis drag exists only for wind yaw angles above a certain analytical threshold, the negative frontal pressures exist at smaller yaw angles and subsequently produce body-axis drag coefficients that are significantly less than those of modern heavy vehicles. The application of this aerodynamic phenomenon to the heavy vehicle industry would produce sizable reductions in petroleum use throughout the United States.

Effects of rear spoilers on ground vehicle aerodynamic drag

2014 ◽  
Vol 24 (3) ◽  
pp. 627-642 ◽  
Author(s):  
Halil Sadettin Hamut ◽  
Rami Salah El-Emam ◽  
Murat Aydin ◽  
Ibrahim Dincer
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Cfd Analysis ◽  
Content Type ◽  
Error Band ◽  
Race Car ◽  
Vehicle Aerodynamics ◽  
Rear Spoiler

Purpose – The purpose of this paper is to examine the aerodynamic effects of rear spoiler geometry on a sports car. Today, due to economical, safety and even environmental concerns, vehicle aerodynamics play a much more significant role in design considerations and rear spoilers play a major role in this area. Design/methodology/approach – A 2-D vehicle geometry of a race car is created and solved using the computational fluid dynamics (CFD) solver FLUENT version 6.3. The aerodynamic effects are analyzed under various vehicle speeds with and without a rear spoiler. The main results are compared to a wind tunnel experiment conducted with 1/18 replica of a Nascar. Findings – By the CFD analysis, the drag coefficient without the spoiler is calculated to be 0.31. When the spoiler is added to the geometry, the drag coefficient increases to 0.36. The computational results with the spoiler are compared with the experimental data, and a good agreement is obtained within a 5.8 percent error band. The uncertainty associated with the experimental results of the drag coefficient is calculated to be 6.1 percent for the wind tunnel testing. The sources of discrepancies between the experimental and numerical results are identified and potential improvements on the model and experiments are provided in the paper. Furthermore, in the CFD model, it is found that the addition of the spoiler caused a decrease in the lift coefficient from 0.26 to 0.05. Originality/value – This paper examines the effects of rear spoiler geometry on vehicle aerodynamic drag by comparing the CFD analysis with wind tunnel experimentation and conducting an uncertainty analysis to assess the reliability of the obtained results.

Vehicle aerodynamics impact of on-road turbulence

2017 ◽  
Vol 231 (9) ◽  
pp. 1148-1159 ◽  
Author(s):  
Bradley Duncan ◽  
Luca D’Alessio ◽  
Joaquin Gargoloff ◽  
Ales Alajbegovic
Keyword(s):  
Real World ◽  
Lattice Boltzmann ◽  
Unsteady Aerodynamics ◽  
Wind Tunnels ◽  
Length Scales ◽  
The Road ◽  
Vehicle Aerodynamics ◽  
On The Road ◽  
Boltzmann Method ◽  
Shape Changes

The ultimate target for vehicle aerodynamicists is to develop vehicles that perform well on the road in real-world conditions. On the other hand, vehicle development today is performed mostly in controlled settings, using wind tunnels and computational fluid dynamics with artificially uniform freestream conditions and neglecting real-world effects due to road turbulence from the wind and other vehicles. Turbulence on the road creates a non-uniform and fluctuating flow field in which the length scales of the fluctuations fully encompass the length scales of the relevant aerodynamic flow structures around the vehicle. These fluctuations can be comparable in size and strength with the vehicle’s own wake oscillations. As a result, this flow environment can have a significant impact on the aerodynamic forces and on the sensitivity of these forces to various shape changes. Some aerodynamic devices and integral design features can perform quite differently from the way in which they do under uniform freestream conditions. In this paper, unsteady aerodynamics simulations are performed using the lattice Boltzmann method on a detailed representative automobile model with several design variants, in order to explore the effect of on-road turbulence on the aerodynamics and the various mechanisms that contribute to these effects.

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