Takeshi Mitsumoji

Aerodynamic Noise Reduction of a Pantograph by Shape-Smoothing of Panhead and Its Support and by the Surface Covering with Porous Material

To reduce aerodynamic noise generated by a pantograph, which is one of the dominant noise sources of high-speed trains, the authors proposed some noise reduction techniques, that is, shape-optimization of a panhead, relaxation of aerodynamic interference between panhead and articulated frame and surface covering with porous material. To evaluate total noise reduction effect of them, wind tunnel tests were performed with a prototype pantograph to which these techniques were applied. The test results show that noise level of the prototype pantograph is lower than that of the currently-used pantograph by about 4 dB. Furthermore, it was also confirmed that the prototype pantograph has enough aerodynamic stability against change of attack angle.

Aerodynamic Noise Reduction of a Pantograph Panhead by Applying a Flow Control Method

To reduce aerodynamic noise generated by a pantograph panhead, a flow control method is applied to the panhead. First, a plasma actuator is applied to the panhead surface to verify that flow control can control flow separation and reduce turbulence intensity behind the panhead. Second, based on the flow control mechanism derived from the experiments applying the plasma actuator, a more practical flow control method is proposed using air suction as an alternative. Experimental results show that air suction near the separation point can reduce narrow band aerodynamic noise from the panhead.

Reduction of Aerodynamic Noise Emitted from Pantograph by Appropriate Aerodynamic Interference Around Pantograph Head Support

Reduction of aerodynamic noise emitted from a pantograph head and its support is one of the important subjects for the speed-up of high-speed trains from an environmental point of view. In this study, to reduce aerodynamic noise emitted from the pantograph head and its support, suitable arrangement of a pantograph head which has a smooth cross section profile, was investigated. The flow field measurement in the wake domain of the pantograph shows that turbulent intensity can be reduced by setting the pantograph head at a suitable position. The reduction of turbulence in the wake domain is caused by appropriate aerodynamic interference between the pantograph head and its support. Furthermore, the results of the aerodynamic noise measurement show that the suitable pantograph head arrangement efficiently reduces aerodynamic noise.