Investigation of the influence of the aerodynamic characteristics of passenger car bodies on the stability of movement and energy consumption in conditions of high-speed highways

Abstract

The article substantiates the critical role of passenger car body aerodynamics for energy efficiency and safety on high-speed rail lines and aims to quantitatively assess the contribution of key geometric solutions to drag and lateral stability at speeds around 350 km/h; the focus is on the nose fairing shape of the leading car, the design of inter-car articulations, and the degree of underbody enclosure, as well as the influence of crosswind modeled via yaw angle. The methodology is based on parametric CFD analysis(RANS, k-ω SST turbulence model) of an eight-car trainset with wind-tunnel data verification; meshes of 45-65 million elements with a moving ground boundary were used to capture trackbed effects, integral coefficients Cx, Cz, Cy, Cn, Cl were computed, and a series of cases at β=0-15° was evaluated. It is shown that increasing the nose fineness ratio from 1.5 to 2,5 reduces Cx by~33% while simultaneously decreasing Cz, whereas further elongation(to 4,0) yields diminishing returns; sealing inter-car gaps with a full bellows gangway reduces the contribution of a single articulation to Cx by nearly an order of magnitude compared to an open configuration and substantially lowers turbulence and pressure pulsations; fully enclosing the underbody with «skirts» reduces the trainset’s total Cx by~21% and reverses the sign of Cz to negative, generating downforce and improving stability. The integrated application of these measures reduces overall aerodynamic resistance by~34-35% and enables potential traction energy savings of 20-25% in cruise, while the optimized configuration shows an 8-12% decrease in lateral force at the same yaw angle relative to the baseline model; the growth of Cy, Cl, and Cn with increasing β follows a quasi-linear dependence, providing inputs for «wheel-rail» dynamic calculations. The discussion highlights an engineering trade-off: underbody closure degrades passive equipment cooling(temperature rise ~+11 °C), requiring coordination of aerodynamics with thermal management; practical takeaways include targets for nose fineness ratio selection(≈3,0-3,5), total sealing of inter-car transitions, and rational underbody shielding, while future work should account for unsteady tunnel and train-passing effects and implement active flow control.