Effects of Tire Attributes on Aerodynamic Performance

2020 ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Drag Force ◽  
Aerodynamic Drag ◽  
Experimental Testing ◽  
Side Wall ◽  
Sensitivity Study ◽  
Aerodynamic Performance ◽  
Baseline Model ◽  
Design Changes ◽  
Boundary Condition Method ◽  
Wall Profile

Abstract As indicated by previous studies, many attributes of tires have been shown to have an impact on tire aerodynamic drag. However, the way these attributes affect tire aerodynamics has not been systematically investigated to date. It is not clear which tire attributes have the most significant impact on aerodynamic drag. Therefore, a sensitivity study of the effects of tire attributes on tire aerodynamic performance is proposed in this study. This sensitivity study improves the understanding of flow structures and mechanisms around tires. First, a baseline CFD model of a tire is created and validated by experimental data. In the computational model, the tire is positioned in a wind tunnel to match the experimental testing configuration. A hybrid boundary condition method is used to simulate a rotating tire. Based on the validated baseline model, various tire attributes are considered and compared in the study proposed. The tire attributes considered include tire width, tire side wall profile, lateral grooves, and open rim design. There are five cases in total for the sensitivity study. Then the effects of these attributes on the tire aerodynamic drag are calculated and compared. The most influencing feature is then identified. The results show that a smoothed side wall profile with smaller radius can improve the aerodynamic performance of an isolated tire. On the other hand, the influence of lateral grooves on tire aerodynamic performance is limited. The force integrated from all lateral groove surfaces only account to less than 2% of the total tire drag force. Additionally, an idealized open rim design changes the flow structure significantly, which leads to the increase of aerodynamic drag. The force integrated on the rim surface account for up to 20% of the overall tire drag force.

scholarly journals Aerodynamic Performance of Road Vehicles

2020 ◽  
Vol 9 (6) ◽  
pp. 642-645
Keyword(s):  
Wind Tunnel ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Aerodynamic Performance ◽  
Polished Surface ◽  
Anova Analysis ◽  
Road Vehicles ◽  
Car Model ◽  
Group Data ◽  
Scale Models

Aerodynamic drag has been experimentally estimated for scale models of a passenger car and a commercial truck in a wind tunnel. Polished surface has resulted up to 15 % reduction in drag force and add-on has resulted in 57% increase in drag force of a car model whereas 2.6 % reduction in drag force has resulted by using deflector in a commercial truck model. Anova analysis shows variation in mean of group data.

Controlling Drag and Down Forces on a Vehicle Side-View Mirror by Applying Vortex Generator Designs on the Bottom Surface

2020 ◽  
Author(s):  
Zulong Dong ◽  
Badih Jawad ◽  
Liping Liu ◽  
Hossam Metwally
Keyword(s):  
Drag Force ◽  
Flow Separation ◽  
Flow Behavior ◽  
Aerodynamic Performance ◽  
Vehicle Body ◽  
Bottom Surface ◽  
Cfd Analysis ◽  
Side View ◽  
Baseline Model ◽  
Back Edge

Abstract Side-view mirrors impact the aerodynamic performance of a vehicle due to the creation of extra drag force, noise, and vibration. This paper presents an alternative practical solution for improving aerodynamic performance of vehicle side-view mirrors. A CFD analysis is conducted for studying the airflow around a side-view mirror with different types of passive vortex generators (VGs) mounted on the bottom surface. VGs are small wingtips that are used to produce swirling motion in the flow stream. In recent years, VGs have been used in vehicle underbody diffusers to delay flow separation and to increase the flow control surface. This study aims to understand the effect of underbody VGs on the flow mechanisms downstream of the side-view mirror, and its impact on both drag and down forces. The turbulent flow behind the side-view mirror is investigated to determine the effects of different VG types and attack angles. Four types of VGs are considered in this work. Changes are made to the baseline model by either adding the VGs close to the frontal edge of the bottom surface of the mirror which aims to control the flow separation, or adding the VGs close to the back edge which aims to reduce the shedding area. Computational Fluid Dynamics (CFD) analysis using ANSYS Fluent is conducted to simulate the flow behavior by using three dimensional Reynolds-averaged Navier-Stokes method with standard K-epsilon (K-ε) turbulence model. In order to incorporate the effect of vehicle body, each model is assembled on a quad-vehicle bluff body for analysis. The drag and down forces are numerically solved and compared with the results of the baseline model at the speeds of 15, 40, 60 and 80 miles per hour. It is concluded from the CFD analysis that: (1) Mounting VGs at the bottom surface of a side-view mirror reduces down force in most cases. (2) Setting underbody VGs at either the front or back edge of the mirror bottom surface has a slight effect on reducing drag force. (3) Multiple types of VGs show improved results with a 30 degree attack angle, which encourages future studies of VG applications with large attack angles.

Silicon template fabrication for imprint lithography with a very smooth side wall profile

2009 ◽  
Vol 517 (14) ◽  
pp. 3862-3865 ◽  
Author(s):  
Hiroaki Kawata ◽  
Masato Matsue ◽  
Kensuke Kubo ◽  
Masaaki Yasuda ◽  
Yoshihiko Hirai
Keyword(s):  
Side Wall ◽  
Imprint Lithography ◽  
Wall Profile

The influence of the thermal wake due to pulsating optical discharge on the aerodynamic-drag force

2018 ◽  
Vol 25 (2) ◽  
pp. 257-264 ◽  
Author(s):  
T. A. Kiseleva ◽  
A. A. Golyshev ◽  
V. I. Yakovlev ◽  
A. M. Orishich
Keyword(s):  
Drag Force ◽  
Aerodynamic Drag ◽  
Optical Discharge ◽  
Thermal Wake

scholarly journals Interaction between an aerodynamically driven, wall-bound drop and a single groove

2020 ◽  
Vol 229 (10) ◽  
pp. 1757-1769 ◽  
Author(s):  
Patrick M. Seiler ◽  
Ilia V. Roisman ◽  
Cameron Tropea
Keyword(s):  
Channel Flow ◽  
Drag Force ◽  
High Speed ◽  
Adhesion Force ◽  
Aerodynamic Drag ◽  
Rear Side ◽  
Threshold Condition ◽  
High Speed Video ◽  
Gravity Forces ◽  
Typical Time

Abstract The interaction between an air-driven, wall-bound drop and a groove in the wall of a channel flow has been investigated experimentally using a high-speed video system. Three major outcomes of drop interaction with the groove are observed: (i) the drop passes over the groove, (ii) the drop is immediately fully captured in the groove or (iii) the drop is captured after first wetting the rear side of the groove. The mechanisms leading to these different outcomes are governed by the aerodynamic drag force, by inertial and gravity forces, and by the adhesion force associated with the substrate wettability. A threshold condition for drop capture is developed, based on the ratio of the typical time for drop passage over the groove to the time for the drop to be sucked into the groove. It has been shown that the probability for drop capture increases for higher Bond numbers.

Vortex Generator Designs to Improve Flow for a Vehicle Side-View Mirror

2019 ◽  
Author(s):  
Zulong Dong ◽  
Badih Jawad ◽  
Liping Liu ◽  
Hossam Metwally
Keyword(s):  
Drag Force ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Cfd Analysis ◽  
Side View ◽  
Baseline Model ◽  
Force Increase ◽  
Flow Improvement

Abstract The unsteady airflow over automotive side-view mirrors is a typical source of turbulence which creates extra drag force, aerodynamic noise and vibration. A CFD analysis is presented for vortex generators (VGs) application on the vehicle side-view mirrors for the purpose of flow improvement. Vortex generators are used to delay flow separation and increase the control surfaces which affect the drag force and down force of the vehicle. Reduced drag force can potentially increase fuel economy, and an increased downforce will increase vehicle grip force and improve vehicle stability which is essential for racing cars. This paper presents practical solutions for mitigating flow turbulence and adjusting down force for existing side-view mirrors. Four VG configurations were designed and numerically analyzed in combination with the baseline model at air speeds ranged from 15 to 80 miles per hour. This research investigated the effect of each VG configuration on the side-view mirror’s aerodynamic performance. The turbulent flow through the side-view mirror were analyzed by using standard K-epsilon (K-ε) Reynolds-averaged Navier-Stokes method. The drag and down forces results were obtained and compared with the baseline model. The CFD analysis concluded the following: (1) Setting the VGs with a 5 degree attack angle on the upwind face of the mirror slightly reduced the drag force. (2) Setting the VGs at the top of the mirror surface greatly increased the downforce with a large drag force increase.

Using SiO2 Hard Mask for Fabrication of Micro Fresnel Focusing Lens for Ultrasonic Ejectors

2020 ◽  
Vol 863 ◽  
pp. 73-78
Author(s):  
Tuan Anh Bui ◽  
Min Chun Pan ◽  
Tzon Han Wu ◽  
Thanh Long Le
Keyword(s):  
Process Parameters ◽  
Side Wall ◽  
Fresnel Lens ◽  
Sio2 Film ◽  
Hard Mask ◽  
Fabrication Procedure ◽  
Fresnel Lenses ◽  
Wall Profile ◽  
Focusing Lens

The fabrication of Fresnel focusing lenses operating at frequencies of 100 and 200 MHz was investigated in order to enhance the focusing efficiency of ultrasonic energy. The effects of process parameters on the four-level Fresnel lens profiles were discussed to find a most feasible fabrication procedure through these experiments. The quality of Fresnel lenses was improved when two-and three-mask processes using SiO2 film as the hard mask were employed. Besides, a better side-wall profile of Fresnel lens was obtained by using the three-mask process as compared to the two-mask one.

scholarly journals Effect of NS-DBD Actuator Parameters on the Aerodynamic Performance of a Flap Lifting Device

2019 ◽  
Vol 9 (23) ◽  
pp. 5213 ◽  
Author(s):  
Kun Chen ◽  
Chen-Yao Wei ◽  
Zhi-Wei Shi
Keyword(s):  
Energy Density ◽  
Flow Field ◽  
Drag Reduction ◽  
Pulse Width ◽  
High Efficiency ◽  
Aerodynamic Drag ◽  
Pulse Discharge ◽  
Excitation Frequency ◽  
Aerodynamic Performance ◽  
Discharge Pulse

The flap lift device is an important part of the conventional configuration of aircrafts and has an important impact on the aerodynamic performance. In this paper, a high-efficiency, simple, and energy-saving nanosecond dielectric barrier discharge (DBD) plasma actuator is placed in the vicinity of the flap lift device to improve the aerodynamic performance of the flap by controlling the flow field. The two-dimensional airfoil GAW-1 and its 29% flap were selected as the research objects, and the nanosecond (NS) DBD actuators were fixed at different locations near the deflection angle of the 10°flap. The excitation frequency, pulse width, and energy density parameters of the pulse discharge were adjusted, and then, the effects of parameter changes on aerodynamic characteristics of the airfoil were studied by numerical simulation. The simulation results show that adjusting the excitation frequency on the aerodynamic drag is weak and that the effect on the aerodynamic lift is obvious. The increase of the discharge pulse width will have a more significant effect on the flow field, i.e., a proper increase of the discharge pulse width can achieve better drag reduction, and increase lift after a stall at a high angle of attack. Although the increase of discharge energy density can strengthen the pulse perturbation effect on the flow field, it also contributes to some adverse effects and has no obvious optimization effect on the control efficiency of lift increase and drag reduction.

Influence of Altitude on the Performance of a Bicycle-Cyclist Set

2017 ◽  
Author(s):  
Mateo Morales ◽  
Sergio D. Roa ◽  
Luis E. Muñoz ◽  
Diego A. Ferreira ◽  
Omar D. Lopez Mejia
Keyword(s):  
High Altitude ◽  
Drag Force ◽  
Power Output ◽  
Aerodynamic Drag ◽  
Integrated Approach ◽  
Cycling Performance ◽  
Air Density ◽  
Effort Tests ◽  
Different Altitudes

There is a tradeoff between power delivery and aerodynamic drag force when cyclists ride at different altitudes. The result is particular to the characteristics of the bicycle as well as the aerobic fitness of the cyclist. This work proposes a methodology based on an integrated approach to the study of the influence of altitude on power output and aerodynamic drag over a particular bicycle-cyclist set. The methodology consists of an independent analysis for each of the effects, to conclude with an integration of results that allows estimating the overall effect of altitude on cycling performance. A case study for the application of the methodology was developed, and the obtained results apply for the specific bicycle-cyclist set under analysis. First, the relationship between power and time was analyzed for a male recreational cyclist based on all-out effort tests at two different altitudes: 237 meters and 2652 meters above sea level (m.a.s.l). Second, the effects of environmental conditions on air density and drag area coefficient due to altitude changes were analyzed based on Computational Fluid Dynamics (CFD) simulations. It was found that for the bicycle-cyclist set under study, the sustainable power output for 1-hour cycling was reduced 45W for the high-altitude condition as a consequence of the reduction in the maximum oxygen uptake capacity. In addition, the aerodynamic drag force is reduced in greater proportion due to the change in air density than due to the change in drag coefficient. Finally, the results of both effects were integrated to analyze the overall influence of altitude on cycling performance. It was found that for the analyzed case study, the aerodynamic advantage at higher altitude dominates over the disadvantage of reduction in power output: despite delivering 45W less, the subject can travel an additional distance of 900 meters during a one hour ride for the high-altitude condition compared to that in low altitude.

scholarly journals Physical and Aerodynamic Properties of Lavender in relation to Harvest Mechanisation

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Christos I. Dimitriadis ◽  
James L. Brighton ◽  
Mike J. O’Dogherty ◽  
Maria I. Kokkora ◽  
Anastasios I. Darras
Keyword(s):  
Surface Area ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Reynolds Numbers ◽  
Ultimate Tensile Stress ◽  
Flower Head ◽  
Drag Forces ◽  
Aerodynamic Properties ◽  
The Mean ◽  
Harvest Moisture

A laboratory study evaluated the physical and aerodynamic properties of lavender cultivars in relation to the design of an improved lavender harvester that allows removal of flowers from the stem using the stripping method. The identification of the flower head adhesion, stem breakage, and aerodynamic drag forces were conducted using an Instron 1122 instrument. Measurements on five lavender cultivars at harvest moisture content showed that the overall mean flower detachment force from the stem was 11.2 N, the mean stem tensile strength was 36.7 N, and the calculated mean ultimate tensile stress of the stem was 17.3 MPa. The aerodynamic measurements showed that the drag force is related with the flower surface area. Increasing the surface area of the flower head by 93% of the “Hidcote” cultivar produced an increase in drag force of between 24.8% and 50.6% for airflow rates of 24 and 65 m s−1, respectively. The terminal velocities of the flower heads of the cultivar ranged between 4.5 and 5.9 m s−1, which results in a mean drag coefficient of 0.44. The values of drag coefficients were compatible with well-established values for the appropriate Reynolds numbers.

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