Optimization on Aerodynamic Performances of Pantograph Combined with Sample Infill Criterion

The increase in the running speed aggravated the influence of the pantograph aerodynamic uplift force on the pantograph-catenary contact force. Moreover, the longitudinal asymmetry of the pantograph makes the aerodynamic uplift force vary greatly under the operating conditions of the knuckle-downstream and knuckle-upstream. Therefore, it is of great significance to optimize the aerodynamic characteristics of the pantograph and ensure the consistency of the aerodynamic uplift force of the pantograph under the two operating conditions. A hybrid infill criterion (HIC) is proposed combining the improved expectation infill criterion (EIC) and the Pareto solution infill criterion (PIC) to improve the optimization efficiency, and the multi-objective aerodynamic optimization of the high-speed pantograph is carried out based on the HIC surrogate model. Taking the single- and multi-objective test function as an example, the convergence speed of EIC, PIC and HIC surrogate models is compared. The results show that the optimization efficiency of the HIC surrogate model is improved by 50.0% compared with the EIC and the PIC surrogate model in the single-objective optimization. For the multi-objective test function, the efficiency of the HIC surrogate model is improved by 62.5%. Further, the Pareto solution set of the pantograph multi-objective optimization is obtained using the PIC surrogate model and genetic algorithm, and the aerodynamic uplift forces of the optimal pantograph under the knuckle-downstream and knuckle-upstream are 36.1 N and 39.9 N, respectively. The pantograph-catenary contact force satisfies the standard considering the static uplift force. Meanwhile, the difference in the aerodynamic uplift forces of the pantograph under two operating conditions is only 3.8 N, and the aerodynamic resistance of the knuckle-downstream and knuckle-upstream operating conditions of the pantograph has been reduced by 1.2%.