Computational and experimental investigation of drag reduction for tractor- trailer geometry using active flow control

Dissertant

Natiq, Nabih

Thesis advisor

al-Khishali, Qutaybah J. M.
Yusuf, Asim Hamid

University

University of Technology

Faculty

-

Department

Department of Electromechanical Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2010

English Abstract

In this study, a numerical and experimental investigation has been carried out to demonstrate the effect of active flow control (AFC) on drag reduction for three-dimensional turbulent flow around heavy vehicle.

The cross wind effect is introduced to simulate yawed flow for a range of yaw angles; 0o, 3o, 6o, 9o, 12o, and 15o.

Three different sets of bleeding configurations are introduced (0.04, 0.05, and 0.06) in the tractor-trailer gap based on the tractor base area and bleed velocity.

The bleeding is introduced by delivering air flow jet through drilled holes at the tractor base.

In contract to the generic conventional model (GCM) that uses a simplified geometry for aerodynamic simulation, a detailed model is introduced in this study for flow investigation.

Within this context, a unique polyhedral mesh is introduced for an accurate prediction of the drag coefficient, where a special emphasis is placed upon the grid quality and resolution.

The first step of this study (case I) is aimed to verify the effectiveness of AFC including tractor base bleeding for 1:32 scaled model.

The experiment is conducted for Reynolds number of 70*103 based on a tunnel velocity of 11.1 m/s and a vehicle width of 9.25cm.

Data acquisition (DAQ) system is built and used to record all aerodynamic forces on the test model.

Force measurements are obtained using a precise load cell.

Comparison between Computational Fluid Dynamics (CFD) and experimental results showed good agreement when predicting the aerodynamic forces (i.e., reduction in drag coefficient) of the vehicle Both CFD and experimental results showed that tractor base bleed can reduce the drag coefficient of tractor-trailer geometry.

Once the results are verified for this case, the performance of tractor base bleed is extended to the full scale geometry (case II) to simulate more realistic operating conditions.

For this case, CFD method is used to simulate the flow around heavy vehicle with Reynolds number of 68*106 based on a vehicle speed and width of 30 m/s and 2.96 m, respectively.

The simulation is demonstrated by investigating the flow structure and rotation, surface pressure, and velocity field around the vehicle and gap region.

The results assess the concept of AFC for drag reduction by reducing the amount of free stream flow entrainment into the gap, and hence reducing the wake and separation.

It is shown that tractor base bleed can reduce the drag coefficient by factor of 21% for the largest bleeding coefficient of 0.06 when cross wind effect is introduced (yawed flow).

Main Subjects

Mechanical Engineering

Topics

• Computing
• Trucks
• Aerodynamics
• Dynamics

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305181