A Novel Approach for Skin Suit Aerodynamic Optimization Using Local Momentum Deficit

Abstract

A new approach is introduced to evaluate the potential drag reduction by skin suit design in speed sport. The approach relies upon local flow information measured in the wake of a cyclist mannequin. Lagrangian Particle Tracking is employed to measure the distribution of time-average streamwise velocity in a cross-plane of 30 × 100 cm2 behind the stretched leg of the rider at a range of Reynolds numbers (0.4 × 105 < Re < 2.4 × 105). The expected Reynolds number effect is observed: a general wake narrowing at increasing speed. Unexpected local effects are also identified, which may be due to local variations in geometry of the rider’s leg. The conservation of momentum within a control volume containing the leg is used showing that the aerodynamic drag of the rider’s leg can be decreased by application of surface roughness. This outcome is validated by repeated measurements using zigzag tape on the legs’ surface.

Keywords

• speed sports
• cycling aerodynamics
• aerodynamic drag optimization
• skin suit
• drag crisis
• Lagrangian Particle Tracking