Aerodynamic characteristics of a high-speed train on flat-box girder for different yaw angles

Abstract

Systematic investigations were conducted to study the flow pattern around a high-speed train on a flat-box girder at different yaw angles in an arrangement between β = [0°, 90°] with 5° increments. Different track positions, such as windward and leeward conditions, were compared. The experimental results revealed that the presence of a flat-box girder significantly influenced the flow pattern around the train, indicating that the train exhibited a predominantly slender body regime in the range of 0° to 30°, a quasi-steady region from 35° to 65°, and the predominance of bluff body characteristics in the range of 70° to 90°. A visualization experiment was conducted to confirm the accuracy of the flow-pattern transition. Under the windward condition, a sudden change in the aerodynamic force was observed in the middle and tail trains at large yaw angles. Analysis of the wind pressure test results for the middle train revealed that the abrupt change was linked to the sudden disappearance of separation bubbles on the upper surface of the train and a reduction in the negative pressure in that area. This study provides reference for high-speed train operation safety.