• Title/Summary/Keyword: 보트 테일

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화물트럭 형상 변화에 따른 공력특성에 관한 수치해석적 연구

  • Ji, Jeong-Seon;Sin, Bo-Chang;U, Dae-Cheon
    • Proceeding of EDISON Challenge
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    • 2016.11a
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    • pp.90-95
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    • 2016
  • 본 연구에서는 교육 및 연구를 위한 CFD 해석 프로그램인 EDISON_CFD 프로그램을 이용하여 화물 트럭의 후면부 형상변화에 따른 공력특성을 분석해보았다. 먼저 추가적인 부착물을 장착하지 않은 기본적인 형상의 화물트럭의 공력특성을 확인 후, 후면부에 여러 형상의 Boat tail(보트 테일)과 전면부에 Cap-roof fairing(캡루프 페어링)이 부착된 형상을 해석하여 트럭이 받는 항력 감소를 통해 최적형상을 찾아가는 연구를 수행하였다. Cap-roof fairing이 부착된 형상에서 $15^{\circ}$의 특성길이가 0.3인 Boat tail에서 가장 좋은 항력 감소 효과를 얻을 수 있었다. Cap-roof fairing의 경우 6%의 항력 계수 감소를 보였고, Boat tail에서 20%의 항력 계수 감소효과를 관찰할 수 있었다. Boat tail의 각도와 길이를 변수로 하여 여러 해석을 진행한 결과 최적화된 형상을 선정할 수 있었다.

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Numerical Study for Base Drag Reduction Using Boattail Shape Afterbodies for Launcher Vehicles in the Supersonic Turbulent Flow (초음속 난류 유동장에 놓인 보트테일 형상 발사체 후방동체 기저 항력 감소에 대한 수치적 연구)

  • Park N. E.;Kim J. S.
    • 한국전산유체공학회:학술대회논문집
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    • 2004.10a
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    • pp.43-46
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    • 2004
  • Numerical analysis for pressure drag on boattail afterbodies have been studied by Mach number, boattail angle and length ratio of body diameter and base diameter using CFD-FASTRAN that the commercial external flow CFD code. The numerical results have been compared with the experimental data that have been shown pressure drag reduction and supersonic turbulent flow characteristics for boattail afterbodies. And the prediction equation tot boattail base drag has been made by the numerical results about Mach number and boattail configuration parameters.

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Drag Reduction of a Three-Dimensional Car Model Using Passive Control Device (수동제어 장치를 이용한 3 차원 자동차 모형의 항력감소)

  • Yi, Wook;SaGong, Woong;Choi, Hae-Cheon
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2868-2872
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    • 2007
  • In this study, a passive control using a boat-tail device is conducted for a three-dimensional car model in ground proximity. We consider various boat-tails and investigate the mechanism of drag reduction by them. By varying the length and slant angle of boat-tail, we obtain drag reductions up to 40%. From the oil-surface flow visualization and hot-wire measurement, the drag reduction by the boat-tail is characterized by the shear-layer instability and reattachment on the boat-tail, forming a small separation bubble at the upstream part of boat-tail surface, resulting in the delay of main separation and drag reduction. At high slant angles, the flow fully separates and drag is nearly same as that of no control.

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On Minimum Time Joint-Trajectory Planning for the Cartesian Straight Line Motion of Industrial Robot (산업용 로보트의 카르테시안 직선 운동을 위한 조인트-궤적의 최소 시간화)

  • 전홍태;오세현
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.24 no.5
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    • pp.753-761
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    • 1987
  • Approximation of a Cartesian straight line motion with linear interpolation in the joint space has many desirable advantages and applications. But inappropriate determination of the corresponding subtravelling and transition times makes such joint-trajectories violate the input torque/force constraints. An approach that can overcome this difficult and yield the joint trajectories utilizing the allowable maximum input torque/force is established in this paper. The effectiveness of these results is demonstrated by using a three-joint revolute manipulator.

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Wind tunnel study on drag reduction of a 5 ton truck using additive devices (유동제어용 부착물을 이용한 5톤 화물차의 항력 감소에 관한 실험적 연구)

  • Lee, EuiJae;Hwang, BaeGeun;Kim, JeongJae;Lee, SangJoon
    • Journal of the Korean Society of Visualization
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    • v.13 no.1
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    • pp.9-14
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    • 2015
  • There have been many attempts to reduce the cost of transportation. Especially, drag reduction of heavy vehicles has enormous influence on energy saving by reducing the driving power of the vehicles. In this study, the effects of drag-reducing additive devices such as side skirt, boat tail and cab-roof fairing on the drag reduction of a 5 ton truck model were experimentally investigated. The aerodynamic performance of these flow-control devices attached to heavy vehicle was evaluated through wind tunnel test. In addition, flow patterns around the truck model were visualized by using smoke tube method. The drag coefficient is reduced by up to 5.7%, 7.16% and 22.2% by the side skirt, boat tail and cab-roof fairing, respectively. The interactive effect of the side skirt and boat tail was also investigated.

Determination of the Minimum Number of Intermediate Points for the Robot Manipulator Cartesian Stright Motion (로보트 매니퓰레이터의 카르테시안 직선운동을 위한 경로집의 최소화)

  • 오세현;전홍태
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.2
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    • pp.144-151
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    • 1988
  • Between any two points in the Cartesian space, the straight motion has many distinct advantages in path/trajectory plannings, specially in a crowded workspace. But to achieve this motion is a nontrivial task. One standard way to approximate this motion is to plae enough intermediate points along the desired path and linearly interpolate two adjacent intermediate points in the joint space. In this approach, however, the determination of the minimum number of intermediate points is very important from several aspects. A scheme that can effectively accomplish this purpose is established in this paper. This scheme is based on several search methods. The results are demonstrated using the PUMA 560 series manipulator.

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Numerical Study on the Enhancement of the Resistant Performance of ROV (선저청소로봇 저항성능 향상에 관한 수치적 연구)

  • Seo, Jang-Hoon;Jeon, Chung-Ho;Yoon, Hyun-Sik;Chun, Ho-Hwan;Kim, Su-Ho;Kim, Tae-Hyung;Woo, Jong-Sik;Joo, Young-Sock
    • Journal of Ocean Engineering and Technology
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    • v.24 no.4
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    • pp.23-31
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    • 2010
  • The flow around a remotely-operated vehicle (ROV) has been investigated numerically to improve the resistant performance by modifying the hull form of the ROV. In the case of the base hull form considered in this study, form drag rather than friction drag was the dominant component of total drag. Subsequently, the surfaces that were most susceptible to local pressure effects were modified to give them a more streamlined shape. Eleven different hull forms were chosen to undergo surface modification for drag reduction. In addition, four different boat-tail appendages with different slant angles were installed at the stern to reduce the wake vortices that are induced by the local regions of very low pressure. Consequently, a total of 11 different hull forms for drag reduction were considered. The final hull form, which combined the hull for which surface modification resulted in the lowest drag with a boat-tail appendage with a 15-degree slant angle, resulted in a drag reduction of 20%.

Numerical Prediction of Acoustic Load Around a Hammerhead Launch Vehicle at Transonic Speed (해머헤드 발사체의 천음속 음향하중 수치해석)

  • Choi, Injeong;Lee, Soogab
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.1
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    • pp.41-52
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    • 2021
  • During atmospheric ascent of a launch vehicle, airborne acoustic loads act on the vehicle and its effect becomes pronounced at transonic speed. In the present study, acoustic loads acting on a hammerhead launch vehicle at a transonic speed have been analyzed using ��-ω SST based IDDES and the results including mean Cp, Cprms, and PSD are compared to available wind-tunnel test data. Mesh dependency of IDDES results has been investigated and it has been concluded that with an appropriate turbulence scale-resolving computational mesh, the characteristic flow features around a transonic hammerhead launch vehicle such as separated shear flow at fairing shoulder and its reattachment on rear body as well as large pressure fluctuation in the region of separated flow behind the boat-tail can be predicted with reasonable accuracy for engineering purposes.

Estimation of GHG Emissions Reduction and Fuel Economy Improvement of Heavy-Duty Trucks by Using Side Skirt and Boat Tail (사이드스커트와 보트테일을 이용한 대형화물차량의 연비개선 효과 및 온실가스 감축량 추정)

  • Her, Chul haeng;Yun, Byoeng gyu;Kim, Dae wook
    • Journal of Climate Change Research
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    • v.7 no.2
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    • pp.177-184
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    • 2016
  • Recently, the need for technology development of commercial vehicle fuel consumption has emerged. Fuel economy improvement of transport equipment and transportation efficiency, and increasing attention to the logistics cost reduction measures. Increasing attention to the logistics cost reduction measures by fuel economy improvement of transport equipment and transportation efficiency. In this study, we have installed aerodynamic reduction device (side skirt, boat tail) to 14.5 ton cargo trucks and 45 ft tractor-trailers. And the fuel consumption was compared installed before and after. Fuel economy assessment for the aerodynamic reduction value device was tested by modifying the SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test in according domestic situation. Greenhouse gas reductions were calculated in accordance with the scenario, including fuel consumption test results. When the 14.5 ton cargo trucks has been equipped with side skirts and boat tail, it confirmed the improvement in fuel efficiency of 4.72%. One Heavy-duty truck's the annual greenhouse gas reductions value are $6.86ton\;CO_2\;eq$. And if applying the technology to more than 50% of registered 15 ton trucks, greenhouse gas reductions are calculated as $686,826ton\;CO_2\;eq./yr$.