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후드를 이용한 협소 터널 미기압파 감소 효과에 대한 수치적 연구
윤수환(Su-Hwan Yun),김병열(Byung-Yeol Kim),구요천(Yo-Cheon Ku),이동호(Dong-ho Lee),권혁빈(Hyeok-Bin Kwon),고태환(Tae-hwan Ko) 한국철도학회 2005 한국철도학회 학술발표대회논문집 Vol.- No.-
The train entry into a tunnel generates a strong compression wave in the tunnel The high amplitude of compression wave causes high pressure gradients that are responsible for both the aural discomfort of passengers and the impulsive acoustical wave called the mira-pressure wave. This paper provides a numerical study on effects of hood for micro-pressure wave reduction. An axisymmetric numerical solver, considering the crass-sectional area of Korean Tilting Train express, is used for a transient flow field in the tunnel Results show that the micro-pressure wave is able to be reduced by a hood. In this results, the maximum reduction of micro-pressure wave is shown at 2L(length), 1.35D(diameter) hood around 56% against the non-hood case.
윤수환(Su-Hwan Yun),김태윤(Tae-Yoon Kim),권혁빈(Hyeok-bin Kwon),이동호(Dong-Ho Lee) 한국철도학회 2004 한국철도학회 학술발표대회논문집 Vol.- No.-
Numerical analysis of aerodynamic characteristics was differently performed according to the running situation of the Korean Tilting Train eXpress(TTX) that would be introduced for an improvement in efficiency of the used railroad track. Fluent6.0 was used for the analysis of Non-tilting case, Tilting case and Passing-by case with the model of TTX. As a result, the aerodynamic drag had little difference between Tilting and Non-tilting case. However, pressure contour under the train of Tilting case was not symmetry because the gap between a train and the ground was different at both sides. And this disparity of pressure worked on the side force. In Passing-by case attraction and counterattraction occurred alternately and affected to the opposite train. When two trains were side by side, the maximum attraction was generated especially. Through an analysis of pressure wave in tunnel a large variation of pressure was generated by the bluff nose of TTX. The results in this study would be good data for the aerodynamic characteristic on TTX and provide important information to judgment of running safety.
윤수환(Su-Hwan Yun),김태윤(Tae-yoon Kim),고태환(Tae-Hwan Ko),권혁빈(Hyeok-bin Kwon),이동호(Dong-ho Lee) 한국철도학회 2004 철도저널 Vol.7 No.3
Numerical analysis of aerodynamic characteristics was differently performed according to the running situation of the Korean Tilting Train express(TTX) that would be introduced for an improvement in efficiency of the used railroad track. Fluent 6.0 was used for the analysis of Non-tilting case, Tilting case and Passing-by case with the model of TTX. As a result, the aerodynamic drag had little difference between Tilting and Non-tilting case. However, pressure contour under the train of Tilting case was not symmetry because the gap between a train and the ground was different at both sides. In Passing-by case attraction and counter attraction occurred alternately and affected to the opposite train. When two trains were side by side, the maximum attraction was generated especially. Through an analysis of pressure wave in tunnel a large variation of pressure was generated by the bluff nose of TTX. The results in this study would be good data for the aerodynamic characteristic on TTX and provide important information to judgment of running safety.
플라즈마 유동제어를 위한 DBD 플라즈마 액츄에이터의 설계변수에 따른 특성 연구
윤수환(Su Hwan Yun),권혁빈(Hyeok Bin Kwon),김태규(Taegyu Kim) 한국항공우주학회 2012 韓國航空宇宙學會誌 Vol.40 No.6
DBD(Dielectric Barrier Discharge) 플라즈마 액츄에이터의 설계 파라미터에 따른 특성을 연구하였다. 방전전압, 주파수, 전극의 간격, 폭, 길이, 유전체 두께에 따른 DBD 플라즈마 액츄에이터의 유속 및 소모전력을 측정하였다. 방전전압과 주파수가 클수록 유속과 소모전력은 증가하였다. 전극간격은 클수록 소모전력은 감소하면서 유속은 증가하였으나, 플라즈마 방전을 위해 높은 전압이 요구되었다. 상부전극폭은 좁을수록, 하부전극폭은 넓을수록 일정한 소모전력으로 유속을 증가시킬 수 있었다. 주어진 방전조건과 전극형상에서 DBD 플라즈마 액츄에이터의 성능을 예측할 수 있을 것으로 기대된다. Characteristics of DBD(Dielectric Barrier Discharge) plasma actuator as design parameters were investigated for plasma flow control. Flow velocity and power consumption of the DBD plasma actuator were measured according to the design parameters such as discharge voltage and frequency, gap, width and length of electrode, and the thickness of dielectric barrier. The flow velocity and power consumption increased as the discharge voltage and frequency increased. As the electrode gap increased, the flow velocity increased with decreasing the power consumption, whereas high voltage was required for the plasma discharge. The flow velocity increased as the upper-electrode width decreased, and as the lower-electrode width increased at the constant power consumption. The performance of the DBD plasma actuator can be estimated at the given discharge and geometry conditions.