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Aerodynamic integration produces a vehicle shape with a negative drag coefficient
Kambiz Salari1, Jason M Ortega2
1Lawrence Livermore National Laboratory, Livermore, CA 94551.
Summary
Heavy trucks can achieve negative aerodynamic drag, reducing fuel consumption, by using specially designed shapes that create a "pulling" effect from crosswinds. This innovation offers significant petroleum savings for the trucking industry.
Area of Science:
- Aerodynamics
- Automotive Engineering
Background:
- Heavy vehicles typically exhibit high aerodynamic drag coefficients.
- Negative drag is usually associated with wind-assisted propulsion systems.
Purpose of the Study:
- To investigate the potential for heavy vehicles to generate negative aerodynamic drag without external appendages.
- To explore novel aerodynamic designs for semi-trucks to reduce fuel consumption.
Main Methods:
- Utilized wind tunnel measurements.
- Employed computational fluid dynamics (CFD) simulations.
Main Results:
- Demonstrated aerodynamically integrated vehicle shapes that produce negative body-axis drag in crosswinds.
- Identified large negative frontal pressures as the mechanism, effectively "pulling" the vehicle forward.
- Achieved body-axis drag coefficients significantly lower than current heavy vehicles.
Conclusions:
- Aerodynamic designs can induce negative drag in heavy trucks, even in crosswinds.
- This phenomenon, driven by negative frontal pressures, can substantially reduce aerodynamic resistance.
- Application to the trucking industry promises significant reductions in petroleum consumption.
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