Flow field analysis and aerodynamic drag optimization of non-pneumatic tires

Numerical simulations were performed to analyze the external flow field characteristics of a non-pneumatic tire (NPT) with flexible spokes. The simulation results revealed that the acute shoulders and cavities formed by spokes are the principal contributors to the high aerodynamic drag and ventilation moment (VM). By changing the parameters of the shear bands, a significant reduction in the aerodynamic drag coefficient (Cd) and ventilation moment could be achieved. Taking the minimum aerodynamic drag coefficient and ventilation moment as optimization objectives, a five-factor and four-level orthogonal experiment was designed with the spoke thickness, spoke radial length, spoke curvature, spoke outer offset rate, and spoke inner offset rate as the design parameters. The optimal combination of spoke parameters was obtained by range analysis and variance analysis, with the reduction of Cd and VM by 6.25% and 16.55%, respectively. Meanwhile, the feasibility of optimization parameters of the shear bands and spokes was confirmed by mechanical performance test.