Experimental and numerical study of the drag coefficient and lateral wind effect on different automobiles geometry

Dissertant

Wahhab, Abd al-Samad Qasim

Thesis advisor

Karam Allah, Abd al-Hasan Abd

University

University of Technology

Faculty

-

Department

Department of Electromechanical Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2009

English Abstract

The effect of the design guidelines on the aerodynarni.es was not of prime importance in the past, bat with the increased concern about future availability of fuel, fuel economy becomes an.

important requirement expected of a modern car or utility vehicle.

Fuel consumption depends, among other factors, on the aerodynamic drag of vehicle.

The first part of the undertaken research deals with an experimental determination of drag coefficient for three, two-and one-box form passenger csr model with different scales by a wind tunnef using a strain gauge technique which was proved to- be practical and reasonably accurate.

Experiments were run within a subsonic aspiration wind tunnel, covering an air speed up to 33m,^s (Reynolds number up to 6.55 x105).

Drag coefficients of 0.45 for Mercedes SEL300, 0.39 for Hyundai, 0.53 for Toyota, 0.34 for Pinero, and 0.6S for SNVI VI mini-bus models, were obtained.

The comparison of the experimental results with those given by other authors gives a satisfactory agreement.

The flow field around the pre-quo ted models with a qualitative description about the flow visualization for each type using a subsonic smoke wind tunnel at 35m / s, have been accomplished.

Flow visualization experiments have been indicated that,, one and two-box form models, attempted to create an after body flow with a shape like a ha If-teardrop.

While three-box form models,. have a distinctly short after body characterized by the definite wake flows and vortices.

The second part of the undertaken research deals with the numerical solution for the aerodynamic influence of different body pr-ofiJes. Three different vehicle segments were considerned : three-.

two- and one-box form passenger car models.

These models were modeled and meshed using the preprocessor of FL-UENT-GAMBIT.

For solving the flow and turbulence parameters, a three dimensional finite volume numerical method and a standard k-£ turbulence model based commercial code FLUENT 5.3, was. used for analysis.

The obtained drag coefficients from the simulation results were 0.31 for three-box.

Form, 0.89 for two-box form and 0.90 for one-box form models.

The comparison for three-box form with those given by reference (37) gives good agreement in which for this reference is CD = 0-347.

Comparison of experimental results with the numerical solutions gives a good impression about the range of drag coefficients for different three types of models.

On the other hand, the complexity of the aerodynamic characteristics of a vehicle, affects on its handling through the aerodynamic lift and the side wind stability.

For this respect, an analytical study of the side component of drag wind force effect on the amplitude ratio for three-boss form passenger car model was carried, out.

The results showed that at a frequency range < 1 .0 Hz, an amplitude ratio of the vehicle was subjected to great changes on its profile with respect to the vehicle speed, while at frequency range .1,0 Hz, there was no obvious difference in the amplitude ratio in both cases (with and without side component of drag wind force effect).

Main Subjects

Mechanical Engineering

Topics

• Islamic jurisprudence
• Automobiles
• Aerodynamics

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305121