Numerical flow simulation of mechanism of increase and method for suppressing increase in lift force of pantograph head of conventional line pantograph under crosswind

Abstract

The aerodynamic characteristics of a conventional line pantograph in a crosswind were investigated by conducting large-eddy simulations (LESs). In a previous study, wind tunnel tests using a full-scale pantograph were performed at various attack angles of the crosswind to understand the lift force characteristics of a pantograph in crosswind conditions. These experiments revealed that the lift force increases significantly when the yaw angle is set to 56°; however, the mechanism of increment of the lift force has not been clarified. Therefore, the flow fields around the pantograph head were investigated. It was found that there are two main mechanisms: one is a stationary large-scale vortex generated on the upper surface of the pantograph head, and the other is a pressure increment on the lower surface of the pantograph head. In addition, LESs were conducted using modified pantograph head shapes to investigate methods for reducing the lift force of the pantograph head using the mechanisms above. Two changes to the pantograph head shape were considered: a diagonal cut on the lower surface of the pantograph head and opening sections on the upper and lower surfaces of the pantograph head. The former shape generates a negative pressure area under the pantograph head, while the latter attenuates the large-scale vortex on the upper surface of the pantograph head. Thus, they achieve lift reduction by different mechanisms and can be used together. The lift reduction rate reaches approximately 60% when both methods are used together, indicating that this is an effective lift force reduction method.