Numerical Investigations of the Influence of Helmet Shape on the Aerodynamic Drag of a Cyclist in Cycling Races

The effect of helmet shape on aerodynamic drag is numerically investigated when cyclists lean during cornering in individual cycling races. Five helmet models (H1–H5) with varying curvatures are constructed, and under the conditions of a vehicle speed of 20 m/s and a 45° body inclination, the SST k-ω turbulence model and grid independence verification (final grid count: 6.75 million) are used to systematically analyze the distribution of velocity, vortex, pressure, and wall shear stress fields. The results show that increasing helmet curvature enlarges the windward area, intensifies rear vortex strength, slows pressure recovery, and ultimately increases drag. The H3 helmet is identified as the optimal choice for individual races due to its stable flow field and minimum drag (268.4 N). Further analysis of different initial speeds (5–25 m/s) reveals that as speed increases, the boundary layer velocity gradient rises, with wall shear stress (0–5 Pa) and drag (100–500 N) also increasing accordingly, while the pressure field decreases gradually due to the Bernoulli effect.