2DHigh-precision measurement of surface pressure distribution and noise of a pantograph in wind tunnel tests
  • Measurement of surface pressure distribution using pressure-sensitive paint to confirm the strong effects of aerodynamic interference between the pantograph head and the frame on the upward force and aerodynamic noise characteristics of pantographs
  • Development of the aero-dynamic noise source localization technique in a wind tunnel test to improve the localization accuracy using microphone array in the vicinity of the main flow.
  •    To measure the surface pressure distribution on a pantograph, the pressure taps are normally used. However, it is difficult to obtain a detailed pressure distribution using this method as the number of pressure taps cannot easily be increased. RTRI therefore applied a technique to measure pressure distribution in detail using pressure-sensitive paint. By this measurement technique, RTRI found that strong aerodynamic interference was generated at the joint between the pantograph head and the frame, significantly influencing the characteristics of the upward force of the pantograph (Fig. 1).
       Microphone array is one of the suitable techniques to localize the aero-dynamic noise sources on Pantographs and other specimens in the wind tunnel test. The localization accuracy can be generally improved by setting the apparatus in the vicinity of the noise sources. However, in order to avoid the self-induced noise making SNR worse, measurements by traditional microphone array are restricted to outside of main flow. In contrast, newly developed measurement method can reduce the influence of sefl-induced noise and allows the microphone array to be measured near the main flow of open/closed test section. This technique can improve the error margin in identifying the noise source at 300km/h from 50mm to about 5mm in the open test section and about 30mm in the closed test section.
       Application of these measuring techniques enable wind tunnel tests to be performed more efficiently, while aiming at improvements in the characteristics of pantograph upward force and aerodynamic noise.


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