The Limits of Drag Behavior for Two Bluff Bodies in Tandem

F. Browand; M. Hammache

doi:10.4271/2004-01-1145

2004-03-08

The Limits of Drag Behavior for Two Bluff Bodies in Tandem 2004-01-1145

We demonstrate the interaction of two truck shapes in tandem. Both trucks experience a decreased drag coefficient from the interaction. The degree of drag saving depends strongly upon the drag coefficients of the model trucks in isolation, and upon how the two trucks are arranged. For the two simplest shapes-parallelepipeds with or without partial leading-edge rounding-the total drag saving can range from 10 percent to 40% at a spacing of 2√A (approximately 18 feet at full scale) depending upon whether the lead or the trail parallelepiped has rounding. These two shapes-blunt and rounded-have drag coefficients in isolation of 0.94 and 0.51 respectively, and probably bracket the savings to be obtained for all real truck geometries.

Our realistic model trucks (with wheels and a gap between tractor and trailer serving to distribute the source of drag along the length of the truck) have drag coefficients in the range C_D = 0.5-0.7, and the total drag saving is a more modest 15-20% at 2√A.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Digital $37.00 Print $37.00

Preview Document

We also recommend:

Standards

SAE Mobilus®

Publications

News

Events

Professional Development

A World in Motion (PreK-12)

Participate with SAE

SAE Membership

Donate

The Limits of Drag Behavior for Two Bluff Bodies in Tandem 2004-01-1145

SAE MOBILUS