Wind tunnel investigations at different inflow velocities were carried out for subcritical, critical and supercritical Reynolds numbers and the dependence of the drag coefficient on the speed was examined. In addition, the effects of insulator sheds made of flexible material were analysed. For a better understanding of the aerodynamic behaviour of cast resin insulators and silicone insulators mounted on trains, different boundary conditions were simulated, which consider realistic configurations corresponding to common train roof structures. The aerodynamic drag of various types of pantograph insulators and other roof insulators was measured. Depending on the boundary conditions mentioned above, a noticeable contribution of the insulators to the aerodynamic drag of the entire train could be observed. Based on the measured drag, the energy consumption caused by the insulators was then determined.
Comparative studies were also carried out on simple cylinders and a generally similar behaviour of the drag coefficient as a function of the flow conditions was shown.
In addition, the influence of flexible insulator sheds on silicone-coated insulators was investigated. It could be observed that the insulators made of soft silicone (RTV, LSR) begin to flutter above a certain inflow velocity, which leads to a strong increase in the drag coefficient for higher flow or pulling speeds.