A Study on the Aerodynamic Drag of a Non-Pneumatic Tire

2012 ◽  
Author(s):  
Hyeonu Heo ◽  
Jaehyung Ju ◽  
Doo-Man Kim ◽  
Sangwa Rhie
Keyword(s):  
Drag Force ◽  
Aerodynamic Drag ◽  
Fuel Efficiency ◽  
Rolling Resistance ◽  
Navier Stokes ◽  
Viscoelastic Materials ◽  
Complex Flow ◽  
Pneumatic Tire ◽  
Rans Method ◽  
Pneumatic Tires

An understanding of the flow around a tire in contact with the ground is important for when designing a fuel efficient tire as aerodynamic drag accounts for about one third of an entire vehicle’s rolling loss [1]. Recently, non-pneumatic tires (NPTs) have drawn attention mainly due to their low rolling resistance associated with the use of low viscoelastic materials in their construction. However, an NPT’s fuel efficiency should be re-evaluated in terms of aerodynamic drag: discrete flexible spokes in an NPT may cause more aerodynamic drag, resulting in greater rolling resistance. In this study, the aerodynamic flow around an NPT in contact with the ground is investigated for i) stationary and ii) rotating cases using the Reynolds-Averaged Navier-Stokes (RANS) method. The NPT has a more complex flow and a higher drag force than does the pneumatic counterpart.

Effect of Underbody Geometry on the Fuel Efficiency of Gasoline and Electric Vehicles

2018 ◽  
Author(s):  
Krishnaswamy Mahadevan ◽  
Fred Barez ◽  
Ernie Thurlow ◽  
Davood Abdollahian
Keyword(s):  
Fuel Consumption ◽  
Drag Force ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Fuel Efficiency ◽  
Rolling Resistance ◽  
Low Pressure ◽  
Ansys Fluent ◽  
Drag Forces ◽  
Pressure Region

Automotive industry in continuously expected to produce more fuel-efficient vehicles. Increasing fuel prices and environmental concerns such as emission of CO2 are two areas in vehicle design improvement. There are multiple factors that affect the fuel economy such as rolling resistance, aerodynamic drag, and weight of the vehicle. As the speed of the vehicle increases, aerodynamic drag force becomes the dominating factor affecting the fuel consumption. This aerodynamic drag is a result of the low-pressure region created at the rear end of the vehicle. This low-pressure region is due to the relative square shape of the vehicle at the rear end which generates vortices. This project aims to investigate the effects of an underbody in reducing the aerodynamic drag forces and its effects on fuel usage. The underbody in vehicles is one such area in improving the aerodynamics of a vehicle which can have an impact on overall drag force. Various underbody geometry modifications were carried out on a 3D model of Fiat 500 Electric and Gasoline versions to simulate the effect of underbody geometry on fuel consumption using the CFD simulation tool ANSYS Fluent. It was concluded that the underbody of vehicle influences the overall aerodynamic drag by 20%. Underbody geometry modification helps in reducing the fuel consumption by decreasing the overall aerodynamic drag of the vehicle.

An Experimental Demonstrator of Semi-Active Tire Damping Enhancement

2015 ◽  
Author(s):  
Vladimir V. Vantsevich ◽  
Gabriel D. Judd
Keyword(s):  
Vibration Control ◽  
Damping Ratio ◽  
Rolling Resistance ◽  
Analysis Procedure ◽  
Power Losses ◽  
External Excitation ◽  
Pneumatic Tire ◽  
Suspension Systems ◽  
Pneumatic Tires

Pneumatic tires play a greater role in vibration control of vehicles with stiff or no suspension systems. The challenge is to find an approach that enhances vibratory damping in the tires without increasing the power losses due to rolling resistance effects. This paper presents a novel tire damping enhancement that allows for improved damping within the tire while maintaining the rolling resistance found in a typical pneumatic tire. The damping enhancement was evaluated by testing an apparatus/demonstrator that simulates a pneumatic tire. The experiment was initially configured to measure the damping ratio of the conventional tire design using a calibrated external excitation and analyzing the decay of the vibration. The damping enhancement presented in the paper was then subjected to the same test and analysis procedure. Results of the analysis show that the proposed damping enhancement measurably decreased the time of the vibratory oscillation.

scholarly journals A numerical model for the time-dependent wake of a pedalling cyclist

2019 ◽  
Vol 233 (4) ◽  
pp. 514-525
Author(s):  
Martin D Griffith ◽  
Timothy N Crouch ◽  
David Burton ◽  
John Sheridan ◽  
Nicholas AT Brown ◽  
...  
Keyword(s):  
Drag Force ◽  
Large Scale ◽  
Aerodynamic Drag ◽  
Experimental Studies ◽  
Wake Flow ◽  
Time Dependent ◽  
Navier Stokes ◽  
Streamwise Vorticity ◽  
Leg Cycling ◽  
The Impact

A method for computing the wake of a pedalling cyclist is detailed and assessed through comparison with experimental studies. The large-scale time-dependent turbulent flow is simulated using the Scale Adaptive Simulation approach based on the Shear Stress Transport Reynolds-averaged Navier–Stokes model. Importantly, the motion of the legs is modelled by joining the model at the hips and knees and imposing solid body rotation and translation to the lower and upper legs. Rapid distortion of the cyclist geometry during pedalling requires frequent interpolation of the flow solution onto new meshes. The impact of numerical errors, that are inherent to this remeshing technique, on the computed aerodynamic drag force is assessed. The dynamic leg simulation was successful in reproducing the oscillation in the drag force experienced by a rider over the pedalling cycle that results from variations in the large-scale wake flow structure. Aerodynamic drag and streamwise vorticity fields obtained for both static and dynamic leg simulations are compared with similar experimental results across the crank cycle. The new technique presented here for simulating pedalling leg cycling flows offers one pathway for improving the assessment of cycling aerodynamic performance compared to using isolated static leg simulations alone, a practice common in optimising the aerodynamics of cyclists through computational fluid dynamics.

Method to Reduce Drag Coefficient for Fuel Efficiency in Semi-Truck Trailer and Trailer Stability

2018 ◽  
Author(s):  
Anu R. Nair ◽  
Fred Barez ◽  
Ernie Thurlow ◽  
Metin Ozen
Keyword(s):  
Drag Coefficient ◽  
Fuel Consumption ◽  
Aerodynamic Drag ◽  
Fuel Efficiency ◽  
Rolling Resistance ◽  
Ansys Fluent ◽  
Improve Fuel Efficiency ◽  
Area Of Interest ◽  
Streamlined Body ◽  
External Forces

Heavy commercial vehicles due to their un-streamlined body shapes are aerodynamically inefficient due to higher fuel consumption as compared to passenger vehicles. The rising demand and use of fossil fuel escalate the amount of carbon dioxide emitted to the environment, thus more efficient tractor-trailer design becomes necessary to be developed. Fuel consumption can be reduced by either improving the driveline losses or by reducing the external forces acting on the truck. These external forces include rolling resistance and aerodynamic drag. When driving at most of the fuel is used to overcome the drag force, thus aerodynamic drag proves an area of interest to study to develop an efficient tractor-trailer design. Tractor-trailers are equipped with standard add-on components such as roof defectors, boat tails and side skirts. Modification of these components helps reduce drag coefficient and improve fuel efficiency. The objective of this study is to determine the most effective geometry of trailer add-on devices in semi-truck trailer design to reduce the drag coefficient to improve fuel efficiency and vehicle stability. The methodology consisted of CFD analysis on Mercedes Benz Actros using ANSYS FLUENT. The simulation was performed on the tractor-trailer at a speed of 30m/s. The analysis was performed with various types of add-on devices such as side skirts, boat tail and vortex generators. From the simulation results, it was observed that addition of tractor-trailer add-on devices proved beneficial over modifying trailer geometry. Combination of add-on devices in the trailer underbody, rear and front sections was more beneficial in reducing drag coefficient as compared to their individual application. Improving fuel efficiency by 17.74%. Stability of the tractor-trailer is improved due to the add-on devices creating a streamlined body and reducing the low-pressure region at the rear end of the trailer.

CFD Analysis of Aerodynamic Drag Reduction in Heavy Vehicles by Changing its Frontal Area: Techinical Note

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
D. Hasen ◽  
S. Elangovan ◽  
M. Sundararaj ◽  
K.M. Parammasivam
Keyword(s):  
Fuel Consumption ◽  
Aerodynamic Drag ◽  
Fuel Efficiency ◽  
Rolling Resistance ◽  
Aerodynamic Performance ◽  
Frontal Area ◽  
Heavy Vehicles ◽  
Design Engineers ◽  
Ansys Cfx ◽  
Aerodynamic Drag Reduction

Nowadays, fuel efficiency of heavy vehicles became an ultimate issue to the manufacturing and design engineers. The best approach to reduce the fuel consumption is to improve the aerodynamic performance of vehicle. This can be achieved by reducing the drag, because drag coefficient is directly proportional with the fuel consumption. Design engineers trying to improve the heavy vehicle’s performance by manipulating various parameters such as engine parameters, weigh, rolling resistance and aerodynamic drag. In this project, efforts were made to increase the aerodynamic performance by changing the frontal area of the container. Computational analysis was carried out at various velocities (50km/hr, 60km/hr, and 70km/hr) by changing the frontal area of the container in heavy vehicles. Different truck geometries were done using CATIA V5 and the simulations were done using ANSYS CFX software. Results were obtained and comparative studies were made. As a result of comparisons between various designs, the cowl of 2h dimension shows better results in reducing the drag when compared with the other designs.

Numerical Analysis of Lateral Skirts Performance on Drag Force of a Semi-Trailer Truck

2018 ◽  
Author(s):  
M. Lateb ◽  
H. Fellouah
Keyword(s):  
Drag Force ◽  
Aerodynamic Drag ◽  
Experimental Results ◽  
Navier Stokes ◽  
Force Parameter ◽  
Cfd Simulations ◽  
Total Drag ◽  
Computational Fluid Dynamics Cfd ◽  
Induced Flow ◽  
Relative Errors

This work performs computational fluid dynamics (CFD) simulations using a transient URANS (unsteady Reynolds averaged Navier–Stokes) turbulence model to investigate the influence of lateral skirts — located in the lower part of a semitrailer truck — in terms of reducing the total drag force and fuel consumption savings. The total drag force values are calculated for three semi-trailer trucks speeds (i.e. 60, 70 and 100 km/h), compared, and then validated against experimental results carried out in a wind tunnel reduced model scale (1:28). The relative errors of the aerodynamic drag force parameter are assessed in order to quantify the accuracy and the reliability of the numerical modeling results with regard to the experimental results. In addition, the flow pattern around the semi-trailer truck is then investigated to determine how the induced flow field is channeled, and where the recirculating zones are modified and developed when using the additional skirt device.

Large-Eddy Simulation of Turbulent Flow Over a Heavy Vehicle With Drag Reduction Devices

2015 ◽  
Author(s):  
Sangseung Lee ◽  
Myeongkyun Kim ◽  
Donghyun You
Keyword(s):  
Drag Reduction ◽  
Stokes Equations ◽  
Aerodynamic Drag ◽  
Fuel Efficiency ◽  
Computational Simulation ◽  
Navier Stokes ◽  
Computational Techniques ◽  
Heavy Vehicle ◽  
Eddy Simulation ◽  
Flow Control Devices

In order to improve the fuel efficiency of heavy vehicles, flow control devices aiming at aerodynamic drag reduction are often utilized. Computational simulation has been widely used in the investigation of fluid dynamics associated with aerodynamic drag over a heavy vehicle and control effects of many drag reduction devices. Most previous studies were, however, conducted using computational techniques based on the Reynolds-averaged Navier-Stokes equations and with rather simplified geometries (i.e., GTS, GCM, and Ahmed body), and therefore, the utility of the understanding of the drag-producing flow physics is often impractical and limited.

Temperature Rise Times in Pneumatic Tires

1976 ◽  
Vol 4 (3) ◽  
pp. 181-189 ◽  
Author(s):  
S. K. Clark
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Temperature Rise ◽  
Thermal Equilibrium ◽  
Transfer Coefficients ◽  
Pneumatic Tire ◽  
Heat Transfer Coefficients ◽  
Idealized Model ◽  
Pneumatic Tires

Abstract An idealized model is proposed for heating of a pneumatic tire. A solution is obtained for the temperature rise of such a model. Using known thermal properties of rubber and known heat transfer coefficients, the time to reach thermal equilibrium is estimated.

On LES Methods Applied to Seal Geometries

2012 ◽  
Author(s):  
James Tyacke ◽  
Richard Jefferson-Loveday ◽  
Paul Tucker
Keyword(s):  
Maximum Error ◽  
Labyrinth Seal ◽  
Navier Stokes ◽  
Final Solution ◽  
Complex Flow ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy ◽  
Rans Models ◽  
Flow Through

Nine Large Eddy Simulation (LES) methods are used to simulate flow through two labyrinth seal geometries and are compared with a wide range of Reynolds-Averaged Navier-Stokes (RANS) solutions. These involve one-equation, two-equation and Reynolds Stress RANS models. Also applied are linear and nonlinear pure LES models, hybrid RANS-Numerical-LES (RANS-NLES) and Numerical-LES (NLES). RANS is found to have a maximum error and a scatter of 20%. A similar level of scatter is also found among the same turbulence model implemented in different codes. In a design context, this makes RANS unusable as a final solution. Results show that LES and RANS-NLES is capable of accurately predicting flow behaviour of two seals with a scatter of less than 5%. The complex flow physics gives rise to both laminar and turbulent zones making most LES models inappropriate. Nonetheless, this is found to have minimal tangible results impact. In accord with experimental observations, the ability of LES to find multiple solutions due to solution non-uniqueness is also observed.

Fluid Flow Structure in Arterial Bypass Anastomosis

2005 ◽  
Vol 127 (4) ◽  
pp. 611-618 ◽  
Author(s):  
C. M. Su ◽  
D. Lee ◽  
R. Tran-Son-Tay ◽  
W. Shyy
Keyword(s):  
Fluid Flow ◽  
Flow Structure ◽  
Bypass Graft ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Complex Flow ◽  
Arterial Bypass ◽  
Flow Recirculation ◽  
Area Reduction ◽  
Complex Flow Structure

The fluid flow through a stenosed artery and its bypass graft in an anastomosis can substantially influence the outcome of bypass surgery. To help improve our understanding of this and related issues, the steady Navier-Stokes flows are computed in an idealized arterial bypass system with partially occluded host artery. Both the residual flow issued from the stenosis—which is potentially important at an earlier stage after grafting—and the complex flow structure induced by the bypass graft are investigated. Seven geometric models, including symmetric and asymmetric stenoses in the host artery, and two major aspects of the bypass system, namely, the effects of area reduction and stenosis asymmetry, are considered. By analyzing the flow characteristics in these configurations, it is found that (1) substantial area reduction leads to flow recirculation in both upstream and downstream of the stenosis and in the host artery near the toe, while diminishes the recirculation zone in the bypass graft near the bifurcation junction, (2) the asymmetry and position of the stenosis can affect the location and size of these recirculation zones, and (3) the curvature of the bypass graft can modify the fluid flow structure in the entire bypass system.

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