Journal of the Institute of Convergence Signal Processing (융합신호처리학회논문지)

The Korea Institute of Convergence Signal Processing (한국융합신호처리학회)
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Study on Minimizing Electromagnetic Interference to Capture Vortex Structures in Turbulent Boundary Layer

경계층 유속 정밀도 증가를 위한 전자파 간섭 최소화 연구

  • Dong-Hoon Kang (Department of Naval Architecture and Ocean Engineering, Gyeongsang National University) ;
  • Yong Duck Kang (Department of Naval Architecture Engineering, Naval Academy)
  • 강동훈 (경상국립대학교 조선해양공학과) ;
  • 강용덕 (해군사관학교 조선공학과)
  • Received : 2024.06.12
  • Accepted : 2024.06.28
  • Published : 2024.06.30
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Abstract

To measure the vortex structures within the turbulent boundary layer, a hot-wire sensor was mounted on a stepper motor controller and moved to the designated measurement points. Near the surface within the flow field, the velocity is relatively slow, making the measurements highly sensitive to electromagnetic interference (EMI) during signal processing. This EMI primarily originates from the power supplies of computers and other electronic equipment. In our experimental setup, EMI was introduced into BNC cables connected to the hot-wire sensor from the powered stepper motor. When power was supplied to the motor controller to move the hot-wire sensor, EMI appeared on the oscilloscope screen. Consequently, unexpected noise was present in the data measured by the hot-wire sensor. To mitigate this and enhance the signal-to-noise ratio (SNR) during measurements, the connecting cables were shielded, and an old computer without EMI shielding was replaced.

난류 경계층 내부 와류 구조물 형상을 측정하기 위해 열선 유속계(Hot-wire sensor)를 스테퍼 모터 컨트롤러(Stepper motor controller)에 고정하여 측정 지점으로 이동시켰다. 유동장 내 표면 근처 유속은 상대적으로 느려 차후 측정 데이터 해석 시 신호처리 과정에서 전자파 간섭으로 민감하게 반응하게 된다. 전자파 잡음은 주로 컴퓨터나 기타 전자 장비의 전원 공급에서 발생하는데, 실험 장비 중 전원이 활성화된 스테퍼 모터(Stepper motor)에서 전자파 잡음이 열선 유속계와 연결된 BNC 케이블로 유입되었다. 이는 열선 유속계를 이동시키기 위해 모터 컨트롤러(Motor controller)에 전원 공급이 인가되면, 오실로스코프 화면에 전자파 잡음이 나타나는 것을 확인하였다. 열선 유속계에서 측정된 데이터에 예상치 못한 잡음이 포함될 가능성이 있으므로, 이를 감소시키고 측정 과정에서 신호대 잡음비(Signal-to -Noise Ratio, SNR)를 향상하도록 연결 케이블을 차폐시키고 전자파가 차단되는 컴퓨터로 교체하였다.

Keywords

Acknowledgement

This research was supported by the research fund for research professors on sabbatical from Gyeongsang National University in 2022 and by the research fund of the Naval Academy Maritime Research Institute in 2024.

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