• Title/Summary/Keyword: aerodynamic test

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Parametric Study on Wing Design of Insect-mimicking Aerial Vehicle with Biplane Configuration (겹 날개를 사용하는 곤충 모방 비행체의 날개 형상에 대한 파라메트릭 연구)

  • Park, Heetae;Kim, Dongmin;Mo, Hyemin;Kim, Lamsu;Lee, Byoungju;Kim, Inrae;Kim, Seungkeun;Ryi, Jaeha;Choi, Jong-Soo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.9
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    • pp.712-722
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    • 2018
  • This paper conducts parametric studies on flapping wing design, one of the most important design parameters of insect-mimicking aerial vehicles. Experimental study on wing shape was done through comparison and analysis of thrust, pitching moment, power consumption, and thrust-to-power ratio. A two-axis balance and hall sensor measure force and moment, and flapping frequency, respectively. Wing configuration is biplane configuration which can develop clap and fling effect. A reference wing shape is a simplified dragonfly's wing and studies on aspect ratio and wing area were implemented. As a result, thrust, pitching moment, and power consumption tend to increase as aspect ratio and area increase. Also, it is found that the flapping mechanism was not normally operated when the main wing has an aspect ratio or area more than each certain value. Finally, the wing shape is determined by comparing thrust-to-power ratio of all wings satisfying the required minimum thrust. However, the stability is not secured due to moment generated by disaccord between thrust line and center of gravity. To cope with this, aerodynamic dampers are used at the top and bottom of the fuselage; then, indoor flight test was attempted for indirect performance verification of the parametric study of the main wing.

Experimental investigation on valve rattle noise of automotive electronic-wastegate turbochargers (차량용 전자식 웨이스트 게이트 터보차져의 밸브 떨림음에 대한 실험적 고찰)

  • Park, Hoil;Eom, Sangbong;Kim, Youngkang;Hwang, Junyoung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.686-686
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    • 2013
  • Automotive turbochargers have become common in gasoline engines as well as diesel engines. They are excellent devices to effectively increase fuel efficiency and power of the engines, but they unfortunately cause several noise problems. The noises are classified into mechanical noises induced from movement of a rotating shaft and aerodynamic noises by air flow in turbochargers. In addition to, there is a mechanical noise caused from movement of an actuator, electronically controlling a wastegate valve. It is called as valve rattle noise. The actuator is connected to a valve through a linkage. The noise occurs only if the valve is open, where the linkage is freely contact to neighbor structures without being constrained by any external forces. This condition allows impacts by the pulsation of exhaust gas, and the vibration from the impacts spreads out through turbine housing, causing the rattle noise. The noise is not in mechanical operating wastegate turbochargers because the linkage of an actuator is strongly connected by actuating force. For the electronic wastegate turbocharger, this paper proposed a test device to show the noise generating mechanism with a small vibration motor having an unbalanced shaft. It also shows how to reduce the noise - reduction of linkage clearances, inserting wave washers into a connection, and applying loose fitting in bushing embracing a valve lever to turbine housing.

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