Ground effect of an inverted double element wing diffuser on a sedan car

Area of Science:

• Automotive Aerodynamics
• Computational Fluid Dynamics

Background:

• Diffusers are crucial for sports car aerodynamics, influencing downforce and drag.
• Existing research often overlooks the interaction between diffusers and rear tires.
• Car design elements like rear shape and wings affect diffuser performance.

Purpose of the Study:

• To investigate the aerodynamic relationship between a double-element inverted wing diffuser and rear tires.
• To quantify the impact of diffuser design parameters on drag and downforce.
• To identify an optimal diffuser configuration for enhanced sports car performance.

Main Methods:

• Utilized computational fluid dynamics (CFD) simulations on a Nissan Sunny (Versa) Almera model.
• Varied parameters including flap gap, overlap distance, and wing ride height.
• Analyzed airflow and aerodynamic forces under different diffuser configurations.

Main Results:

• Wing ride height was found to significantly affect diffuser flow and base pressure.
• Increasing ride height initially decreased base pressure, then increased downforce.
• An optimal design with a 154 mm ride height, 10 mm gap, and 5 mm overlap was identified.

Conclusions:

• The optimized double-element diffuser design substantially enhances aerodynamic performance.
• The selected design achieved a tenfold increase in downforce and a 2.7% drag reduction.
• This study provides a quantitative basis for diffuser design optimization in sports cars.