scholarly journals On the effects of thermal wake from the optical pulsating discharge on the body aerodynamic drag

2018 ◽  
Author(s):  
T. A. Kiseleva ◽  
A. A. Golyshev ◽  
V. I. Yakovlev ◽  
A. M. Orishich
Keyword(s):  
Aerodynamic Drag ◽  
The Body ◽  
Thermal Wake

Theoretical and Numerical Calculation on the Added Mass of Ahmed Body

2017 ◽  
Vol 865 ◽  
pp. 247-252
Author(s):  
Gui Tao Du
Keyword(s):  
Numerical Calculation ◽  
Theoretical Calculation ◽  
Calculation Method ◽  
Aerodynamic Drag ◽  
Added Mass ◽  
The Body ◽  
Power Performance ◽  
Car Body ◽  
The Impact ◽  
Ahmed Body

Because of the added mass, the aerodynamic drag of the automobile will increase obviously when accelerating in the still air. In this paper, it firstly gave the definition of the added mass, and presented that there was little research on the calculation of the added mass of automobile. Then through the analysis of the theoretical calculation method for the added mass, it pointed out that, for the added mass of the car-body with a complex shape, there was much difficulty in the theoretical calculation. Alternatively, a numerical calculation method for the added mass of car-body was derived. The simulation model adopted the Ahmed body and the corresponding verification experiment was completed in the Tongji Automotive Wind Tunnel center. The results indicate that the added mass is a constant which is only dependent on the body-shape. For the model investigated, the added mass is 0.0052kg that is approximately equal to the air displaced by the car-body. As the body accelerates to 4m/s2, the aerodynamic drag is increased by 1.89% because of added mass. Therefore, it needs to pay more attention to the impact that the added mass has on the dynamic performance of vehicle when proceeding the aerodynamic designs (especially for the high power performance vehicles). Meanwhile, it still makes a correction to the conventional aerodynamic drag formula. This paper also demonstrates that, with the analysis of the flow-field of car-body, the added mass essentially stems from the additionally work done by the car-body to increase the kinetic energy of external fluid as it speeds up.

A Novel Training Bike and Camera System to Evaluate Pose of Cyclists

2020 ◽  
Author(s):  
Raman Garimella ◽  
Koen Beyers ◽  
Thomas Peeters ◽  
Stijn Verwulgen ◽  
Seppe Sels ◽  
...  
Keyword(s):  
Inertial Sensors ◽  
Sagittal Plane ◽  
Aerodynamic Drag ◽  
Linear Regression Analysis ◽  
The Body ◽  
Frontal Area ◽  
Motion Sensors ◽  
Joint Angles ◽  
Camera System ◽  
Flexion Extension

Abstract Aerodynamic drag force can account for up to 90% of the opposing force experienced by a cyclist. Therefore, aerodynamic testing and efficiency is a priority in cycling. An inexpensive method to optimize performance is required. In this study, we evaluate a novel indoor setup as a tool for aerodynamic pose training. The setup consists of a bike, indoor home trainer, camera, and wearable inertial motion sensors. A camera calculates frontal area of the cyclist and the trainer varies resistance to the cyclist by using this as an input. To guide a cyclist to assume an optimal pose, joint angles of the body are an objective metric. To track joint angles, two methods were evaluated: optical (RGB camera for the two-dimensional angles in sagittal plane of 6 joints), and inertial sensors (wearable sensors for three-dimensional angles of 13 joints). One (1) male amateur cyclist was instructed to recreate certain static and dynamic poses on the bike. The inertial sensors provide excellent results (absolute error = 0.28°) for knee joint. Based on linear regression analysis, frontal area can be best predicted (correlation > 0.4) by chest anterior/posterior tilt, pelvis left/right rotation, neck flexion/extension, chest left/right rotation, and chest left/right lateral tilt (p < 0.01).

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

Design of an Hydrogen Powered Electrical Race Vehicle

2011 ◽  
Author(s):  
G. Galmarini ◽  
G. Mastinu ◽  
M. Gobbi ◽  
M. Mauri
Keyword(s):  
Fuel Consumption ◽  
High Performance ◽  
Aerodynamic Drag ◽  
Fem Analysis ◽  
The Body ◽  
Cfd Analysis ◽  
Space Requirement ◽  
Aerodynamic Shape ◽  
Vehicle Shape ◽  
Technical Regulations

The construction of a hydrogen powered electrical race vehicle is presented in this paper. This prototype has been developed to be used in the Shell Eco-Marathon competition. The main aim of this event is to reduce the fuel consumption. According to the technical regulations, the minimum space requirement has been estimated on the basis of the driver anthropometric dimensions. A high performance aerodynamic shape has been developed by starting from an axis-symmetric body which has been optimized for reducing the aerodynamic drag while running close to the ground. CFD analysis has been performed to refine the vehicle shape and to reach the final body geometry. With the help of the FEM analysis, a complex CFRP layout of a monocoque chassis has been defined in order to maximize the body stiffness and to reduce the mass. All the subsystems have been optimized both to reduce the resistance of the vehicle and to maximize the powertrain efficiency. Lab tests have been performed to validate the CFD and FEM analysis. The result of this work is the design of a vehicle, optimized in shape, mass and efficiency, to take part at Shell Eco-Marathon competition.

scholarly journals CFD Analysis of the Influence of the Front Wing Setup on a Time Attack Sports Car’s Aerodynamics

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7907
Author(s):  
Maciej Szudarek ◽  
Janusz Piechna
Keyword(s):  
Aerodynamic Drag ◽  
Aerodynamic Characteristics ◽  
Vital Role ◽  
Front Axle ◽  
The Body ◽  
Strong Interactions ◽  
Unexpected Result ◽  
Proper Position ◽  
Pressure Distributions ◽  
Front Wing

In time attack races, aerodynamics plays a vital role in achieving short track times. These races are characterized by frequent braking and acceleration supported by aerodynamic downforce. Usually, typical cars are modified for these races by amateurs. Adjusting the aerodynamic solutions to work with bodies developed for other flow conditions is difficult. This paper presents the results of a numerical analysis of the effects of installing a straight wing in front of or above the body on the modified vehicle system’s aerodynamic characteristics, particularly on the front wheels’ aerodynamic downforce values. The paper presents the methodology and results of calculations of the aerodynamic characteristics of a car with an additional wing placed in various positions in relation to the body. The numerical results are presented (Cd, Cl, Cm, Clf, Clr), as well as exemplary pressure distributions, pathlines, and visualizations of vortex structures. Strong interactions between the wing operation and body streamline structure are shown. An interesting and unexpected result of the analysis is that the possibility of obtaining aerodynamic downforce of the front wheels is identified, without an increase in aerodynamic drag, by means of a wing placed in a proper position in front of the body. A successful attempt to balance the additional downforce coming from the front wing on the front axle is made using a larger spoiler. However, for large angles of attack, periodically unsteady flow is captured with frequency oscillations of ca. 6–12 Hz at a car speed of 40 m/s, which may interfere with the sports car’s natural suspension frequency.

Some Features of Pulse-Periodic Energy Supply in Supersonic Flow

2010 ◽  
Vol 5 (2) ◽  
pp. 43-54
Author(s):  
Vladimir N. Zudov ◽  
Pavel K. Tretyakov ◽  
Andrey V. Tupikin
Keyword(s):  
Physical Model ◽  
Energy Supply ◽  
Aerodynamic Drag ◽  
Reverse Flow ◽  
High Sensitivity ◽  
Quantitative Agreement ◽  
Frequency Effect ◽  
Experimental Investigations ◽  
Supply Source ◽  
Thermal Wake

In the present work, the results of numerical and experimental investigations of supersonic flows with a localized energy supply are considered. The energy supply region (the heat source) was formed by the plasma created by a focused pulsed-periodic laser emission either by combustion in the separation zone upstream of the blunted body. The main attention is paid to the unsteady effects the role of which is determining at the integral flow structure formation. A physical model of energy source is formulated. The numerical and experimental data on the structure of the flow around the source and the characteristics of a thermal wake arising behind the source are compared. The energy pulses frequency and capacity are shown to determine the wake properties: the formation and development of subsonic regions, vortex structures, and reverse flow regions. It follows from an analysis of the aerodynamic drag variation at a flow with a thermal wake of the energy supply source around blunt bodies that the energy and pulse as well as its duration are the main parameters determining the efficiency of the frequency effect. A high sensitivity of the results to the physical model accepted in numerical investigation is shown. The pressure variation dynamics on a conical surface is presented versus the frequency of pulses. Comparison with experiment has shown a good quantitative agreement.

Application of Computional Fluid Dynamics for Study of the Occurrence of Aerodynamic Effect for its Application in the Construction of Electric Race Car

2015 ◽  
Vol 809-810 ◽  
pp. 956-961
Author(s):  
Łukasz Grabowski ◽  
Andrzej Baier ◽  
Andrzej Buchacz ◽  
Michał Majzner ◽  
Michał Sobek
Keyword(s):  
Fluid Dynamics ◽  
Aerodynamic Drag ◽  
The Body ◽  
Air Velocity ◽  
Race Car ◽  
Drag Forces ◽  
Graphic Analysis ◽  
Aerodynamic Effect ◽  
Air Streams ◽  
The Ideal

In this article the issues related to Computional Fluid Dynamics of the occurrence of innovative aerodynamic effect were presented. Analysis were performed to determine the occurrence of Kammback aerodynamic effect and its application in a shape of a body of the real racing car in order to minimize drag forces of the vehicle. For the analysis, ideal aerodynamic shapes were modeled, subsequently they were subjected to modifications which were used to determine the occurrence of effect. The basic modeled shape was the raindrop shape solid, which is generally regarded as the ideal shape in terms of aerodynamics. The result of analysis was compared with the drag values known from the literature. Afterwards changes in the shape of the base solid were made to verify and determine the optimum Kammback shape, selected from a set of possible solutions, in which the geometrical changes has the lowest difference of values of drag force and drag coefficientCx(Cd)in comparison to the basic raindrop shape. Results of the study were subjected to graphic analysis, especially the distribution of air pressure on the surface of a solid and in a virtual wind tunnel, distribution of the air velocity and the course of air streams around the shape. The results were used to design the body of electric race car. The main objective was to minimize the aerodynamic drag of the vehicle.

Analysis of Turbulence Characteristics in the Laminar Sub-Layer Region of a Perturbed Turbulent Boundary Layer

2016 ◽  
Vol 836 ◽  
pp. 115-120 ◽  
Author(s):  
S. Sutardi ◽  
Wawan Aries Widodo
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Aerodynamic Drag ◽  
Boundary Layer Separation ◽  
The Body ◽  
Mean Velocity ◽  
Test Plate ◽  
Layer Effect ◽  
Layer Region ◽  
Anemometer System

Turbulent boundary layer plays an important role for generation of aerodynamic drag. Shear force and pressure force due to the presence of boundary layer separation from the body surface contribute to the total drag. Studies of drag reduction due the the boundary layer effect are continuously performed by many researchers. Present study is intended to evaluate the behaviour of the laminar sub-layer in a turbulent boundary layer using a hot-wire anemometer system. The study was conducted in a low-speed wind tunnel at a Reynolds number based on the momentum thickness of approximately Reθ = 1000. A smooth-flat plate and a plate with a single transverse square groove was used in the study of the boundary layer characteristics. The groove size of 10 mm x 10 mm was cut transversally across the test plate. The results show that no significant differences in the streamwise mean velocity, steamwise turbulence intensity, and velocity signals for the smooth-and grooved-wall cases. For the the energy spectra for the two cases, however, show significant differences.

scholarly journals Numerical Analysis of Aerodynamic Characteristics of a of High-Speed Car With Movable Bodywork Elements

2015 ◽  
Vol 62 (4) ◽  
pp. 451-476 ◽  
Author(s):  
Tomasz Janson ◽  
Janusz Piechna
Keyword(s):  
Numerical Analysis ◽  
High Speed ◽  
Transient Flow ◽  
Aerodynamic Drag ◽  
Position Angle ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Ansys Fluent ◽  
Drag Forces ◽  
And Performance

Abstract This paper presents the results of numerical analysis of aerodynamic characteristics of a sports car equipped with movable aerodynamic elements. The effects of size, shape, position, angle of inclination of the moving flaps on the aerodynamic downforce and aerodynamic drag forces acting on the vehicle were investigated. The calculations were performed with the help of the ANSYS-Fluent CFD software. The transient flow of incompressible fluid around the car body with moving flaps, with modeled turbulence (model Spalart-Allmaras or SAS), was simulated. The paper presents examples of effective flap configuration, and the example of configuration which does not generate aerodynamic downforce. One compares the change in the forces generated at different angles of flap opening, pressure distribution, and visualization of streamlines around the body. There are shown the physical reasons for the observed abnormal characteristics of some flap configurations. The results of calculations are presented in the form of pressure contours, pathlines, and force changes in the function of the angle of flap rotation. There is also presented estimated practical suitability of particular flap configurations for controlling the high-speed car stability and performance.

scholarly journals CFD MODELLING OF VOLTACAR ELECTRIC VEHICLE BODY FOR THE MOST EFFICIENT DRIVING CONDITIONS

2021 ◽  
Vol 1 (3) ◽  
Author(s):  
Yakup Ogun Süzen ◽  
Emre Özdoğan ◽  
İbrahim San ◽  
Batuhan Gürbüz ◽  
Mehmet Kaçar ◽  
...  
Keyword(s):  
Electric Vehicle ◽  
Aerodynamic Drag ◽  
Low Cost ◽  
Computation Time ◽  
The Body ◽  
Vehicle Body ◽  
Tetrahedral Mesh ◽  
Cfd Modelling ◽  
Mesh Structure ◽  
Driving Conditions

In recent years, fossil fuels prices, greenhouse gas emissions, and need for sustainable energy sources have been increasing day by day. Thus, electric vehicles are seen as a promising candidate in the market due to their low-costs and cleaner fuel options such as electricity, hydrogen etc. Moreover, aerodynamics is one of the most important criteria to consider while designing an automobile for the most efficient driving conditions. For this reason, vehicle developers are studying to reduce drag resistance of the body to improve driving efficiency. On the other hand, Computational Fluid Dynamics (CFD) is one of the main tools for the automotive industry to obtain low-cost results before prototyping of any product. In this study, the aerodynamic characteristics of VoltaCAR electric vehicle is numerically investigated to obtain the best driving velocity. This car participates the TUBITAK-Electromobile car competition every year to achieve low fuel consumption for one hour driving. Thus, it is aimed that to minimize the resistance of the air hitting from the front, side, and roof of the vehicle. In the numerical model, polyhedral mesh structure is preferred to obtain faster convergence with fewer iterations, and shorter computation time is obtained compared to the tetrahedral mesh method. The aerodynamic drag coefficient (Cd) of the car model was calculated as approximately 0.17 at 22.22 and 27.78 m/s. The optimum velocity values were selected as 22.22 and 27.78 m/s by means of their lower Cd.

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