Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-25

AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF
VEHICLE SPACING ON BOUNDARY LAYER
CHARACTERISTICS IN THE 2-VEHICLES PLATOON
 

A.Motin and M.A.T. Ali
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka,
Bangladesh.

ABSTRACT

Aerodynamic shape of a moving object is a major concern of the researchers from many years. Though different accessories, engine parts and passenger compartment for example in the moving vehicle are needed to be available, perfect aerodynamic shape of any body, like passenger car, is not possible to maintain. In this circumstance, alternate factor other than body shape which can affects the vehicle performance is required to keep in consideration. For this, aerodynamic characteristics of two vehicles moving in platoon maneuver are investigated as the function of vehicle spacing (space between two vehicles) in this study. To conduct this investigation, 1/32 scale models of a saloon car are tested in the 300x300 mm wind tunnel facility of the Department of Mechanical Engineering, BUET. Velocities in the vertical plane through the centre of the wind tunnel are measured by pitot static tube which is interfaced with a computer through pressure transducer for data acquisition and is traversed by a computer controlled 3-axes co-ordinate positioning device. The integral analysis of the boundary layer is used to quantify the behavior of the aerodynamic characteristics and the effects of vehicle spacing on the boundary layer characteristics and skin friction. The zone of flow separation approaching laminar-turbulent transition is also investigated. In this study the displacement and momentum thicknesses on the trailing vehicle are found to be higher for smaller vehicle spacing. The flow strikes the front of the vehicle and is accelerated over the bonnet and is observed to be separated from the rear zone of the bonnet but reattaches in the leading edge of the roof. The flow reattachment becomes little bit earlier in the trailing vehicle than that in the leading vehicle.
 

Keywords: Boundary Layer, Flow Separation, Platoon Vehicle, Friction Drag, Friction Coefficient.

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