Abstract

• This study was conducted to give insight to ways to

produce simple and efficient ways to raise tractor trailer

trucks mpg, thus lowering the cost annually of the average truck (which is currently about $100,000). This study’s main focus point was on the tractor because the tractor is responsible for two points of highest drag on the truck (front and gap). The current average tractor could be seen as an aerodynamic disaster while on the other hand this study explores the use of a right traingle shaped tractor, which is one of the most efficient shapes going into direct head winds. This study also exhibits the use of grooves on the tractor model to provide for smoother flow over the vehicle. The idea for grooves was derived from a pilot study exploring the usage of grooves for smoother flow and reduction in drag.

Need

• The average truck uses about 30,000 gallons annually• One tractor trailer truck cost $100,000 annually with

current diesel prices• Trucks make up 80% of the US 580 billion dollar freight

payroll• Low mileage due to dirty aerodynamic structures• Two highest points of drag located in tractor area

Knowledge Base

Graph depicting the five highest areas of drag on a tractor trailer truck

Literature Review

(Wood, Richard and Bauer, Steven)

• Studys also done by Toon (GTRI)

•Hammache (USC)

•McCallen (DOE)

Purpose

• The purpose of this experiment is to explore ways to make tractor trailer trucks more aerodynamically clean by modifying the tractor to the shape of a right triangle to reduce resistance to flow

Hypothesis

• Null Hypothesis- The treatment of grooves on a right triangle will come out to have the same drag as a normal right triangle. Based on a previous pilot study, the null hypothesis should be a true negative.

• Alternate Hypothesis- The treatment of grooves on a right triangle will reduce the drag on the right triangle by stabilizing flow over the right triangle. Based on a previous pilot study, the alternate hypothesis should be a true positive.

Pilot Study for Highest Drag Resistance

Cube Sphere Cone Pyramid

Test three trials in Pitsco Air Tech X Stream Wind tunnel at speeds of 100, 500, 900, 1300, 1700, 2100, 2500 and 2900 ft/min

Testing for drag using Pasco force meter and plugging drag coefficient into drag equation (D=Cd(ρxv2/2)A

Compare shape drag to each other, thus finding most efficient shape

AirfoilCylinderAirfoil w/ Grooves

Right Triangle

Right Triangle w/ Grooves

The effects of grooved right triangles on drag

Right triangle

Right triangle with grooved front

Right triangle with grooved sides

Right triangle with grooved front and sides

Test three trials in Pitsco Air Tech X Stream Wind tunnel at speeds of 100, 500, 900, 1300, 1700, 2100, 2500 and 2900 ft/min

Testing for drag using Pasco force meter and plugging drag coefficient into drag equation (D=Cd(ρxv2/2)A

Compare variable data to control and determine change in drag

Compare best variable to average tractor’s drag and determine drag reduction