Fundamentals of and Improvements in Commercial Vehicle Aerodynamic Drag     


I.D.# C0919Printable Description
Duration: 2 Days

Now, more than ever before, the design and operation of commercial vehicles is influenced by the need to address emissions regulations and government-mandated fuel economy standards. With continued concerns among commercial vehicle owners and operators about rising fuel prices and the impact on operating costs, OEMs and aftermarket developers are actively pursuing technologies that reduce aerodynamic drag and increase vehicle efficiencies. Integrating drag-reducing technology and add-on devices into a commercial vehicle requires an understanding of aerodynamic principles. In addition, understanding the trade-offs in support of vehicle function and operational requirements plays a key role in the integration process.

This two-day seminar will detail the fundamentals of aerodynamic drag, basic shape parameters, and airflow patterns that occur through and around commercial vehicles. In addition, drag reducing concepts, technology and devices currently in use and estimating fuel economy benefits will also be discussed. The examination of various tools and methods (wind tunnels, on-road testing, airflow visualization, CFD) for designing and evaluating drag reduction concepts will be beneficial for attendees, particularly engineers and developers. Finally, scale model testing, drag and pressure measurement methods, data interpretation, and the influence of crosswinds and interpretation of surface pressures will provide attendees a comprehensive learning experience on the topic of commercial vehicle aerodynamics.

Attendees will receive a copy of SAE J1252- Wind Tunnel Test Procedure for Trucks and Buses

Learning Objectives
By attending this seminar, you will be able to:

  • Describe the fundamental principles of commercial vehicle aerodynamic drag, with specific application to heavy duty trucks
  • Identify the major sources of aerodynamic drag and related vehicle shape parameters
  • Identify best practices of good design for reducing drag
  • Explain the integration trade-offs related to vehicle function and operating requirements
  • Implement appropriate methods to develop/verify drag reduction proposals
  • Apply wind tunnel and/or on-road methods for assessing vehicle fuel economy benefits
  • Describe the basics of flow visualization and instrumentation needed to measure and understand airflows and to interpret aerodynamic data

Who Should Attend
This seminar will be beneficial to engineers, product designers, developers, owner/operators, and others that are relatively new to vehicle aerodynamics or are associated with projects or purchasing decisions where vehicle aerodynamics plays an important role in improving fuel economy. Other individuals wanting to improve their understanding of drag reduction principles will appreciate the balance between theory and application and find this course very helpful.

Participants should have an undergraduate engineering degree.

Topical Outline

  • The Motivation for Improving Commercial Vehicle Fuel Economy
    • EPA regulatory announcement
    • NHTSA factors and considerations for (proposed) vehicle economy standard
    • NAS report on technologies to reducing fuel consumption
    • EPA SmartWay certification program
    • Vehicle classification and duty cycles
    • Aerodynamic drag and fuel consumption rules of thumb
    • Certification metrics for regulation and aerodynamic assessment
  • Basic Concepts of Fluid Mechanics
    • Fluid statics and static pressure
    • Real & ideal flow
    • Viscous effects – laminar & turbulent boundary layers
    • Reynolds number
    • Dimensional analysis and similitude
  • Fluid Dynamics and the Bernoulli Equation
    • Aerodynamics and the Laws of Physics
    • Bernoulli’s equation
    • Streamlines
    • Pressure coefficient
    • Wind pressure
    • Internal flow
    • Applications & flow visualization videos
  • Understanding External Flow
    • Potential (ideal) flow
    • Viscous effects and separation – boundary layers
    • Flow separation causes pressure drag
    • Characteristic vehicle flow features
    • Forces on immersed bodies
    • Bluff bodies and interference effects
    • Videos to support basic concepts
  • Commercial Vehicle Aerodynamics
    • SAE J1252
    • SUV drag components
    • Typical drag coefficients (CD)
      • Car & light truck
      • Commercial vehicles
    • Studies on intercity buses and coaches
    • NASA Dryden on-road truck studies
    • Aerodynamics of combination vehicles and straight trucks
    • Guidelines for reducing drag
    • Operational considerations
    • Wind average drag coefficient
    • Additional information
      • Cooling drag
      • Vehicle aspect ratio and ground interaction
      • The NRC aerodynamics test program
  • Additional Information on Vehicle Aerodynamics
    • Commercial vehicle industry developments
    • More on the aerodynamics of tractors and trailers
    • Operational, FMCSA & safety considerations
    • Pneumatic aerodynamics for HD vehicle drag reduction
  • Experimental Methods
    • Wind tunnels
    • SAE J1321 Type II fuel consumption procedure
    • Scale model testing & ground simulation alternatives
    • Effect of Reynolds number – Critical Reynolds number
    • Flow visualization
    • Additional information
      • Wind tunnel balances and data interference effects
      • Wind tunnel-to-road drag correlation
      • EPA modified J2263 coast down procedure for HD vehicles
  • Computational Fluid Dynamics (CFD) for Product Development
    • Introductory comments on CFD methodology
    • An application of CFD to commercial vehicles from DOE
    • Verifying results – an example
    • Calibrating CAE tools for product design
    • Role of CFD in the product design process – some strengths & weaknesses

Instructor(s): Jack Williams

Mr. Williams is the principal at Airflow & Aerodynamics Engineering, LLC and an independent consultant specializing in the design and development of thermal management systems and vehicle aerodynamics. He is an adjunct faculty member at the Lawrence Technological University (LTU) and a guest lecturer for their MSAE Program on Automotive Mechanical Systems. In addition to his consulting work, he conducts professional development seminars for engineers on cooling systems, HEV battery thermal management, and road vehicle aerodynamics. Mr. Williams has over thirty years engineering management experience in product development at Ford Motor Co. Additionally, he was an aerodynamics project leader with the USAF Aeronautical Systems Division at Wright-Patterson Air Force Base, Ohio where he specialized in engine/aircraft integration, gas turbine engine performance, inlet design, and aircraft mission analysis. An active member of the SAE, Mr. Williams has authored over twenty technical papers, given invited lectures at major mid-west universities, and has received professional awards and international recognition for his innovative work. He is a recipient of the Henry Ford II Technology Award, the SAE Industrial Lectureship Award, the SAE Oral Presentation Award, and the SAE Forest R. McFarland Award. He holds a B.S. in Aeronautical Engineering from the University of Detroit and an M.S. in Aerospace/Mechanical Engineering from the United States Air Force Institute of Technology.

Fees: $1335.00 ; SAE Members: $1065.00 - $1205.00

1.3 CEUs
You must complete all course contact hours and successfully pass the learning assessment to obtain CEUs.

"Very knowledgeable, shared interesting insights from experience."
Marc Belzile
ADV Vehicles Program Engineer
Transport Canada

"I think the seminar was a quality class on Aerodynamics. It was immensely informative with excellent case studies used to elaborate concepts. There was a perfect balance of Fluid Mechanics fundamentals and application with ample instructor-attendee interaction. I would certainly recommend this class to those working on Road Vehicle Aerodynamics - especially to those new to the field."
Milind Khandare
Associate Aerodynamics Engineer
Body Engineering Center of Excellence at Navistar Inc.

For additional information, contact SAE Customer Service at 1-877-606-7323 (724/776-4970 outside the U.S. and Canada) or at

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