• Title, Summary, Keyword: Ground Clearance

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Numerical And Experimental Studies On Wing In Ground Effect

  • Suh, Sung-Bu;Jung, Kwang-Hyo;Chun, Ho-Hwan
    • International Journal of Ocean System Engineering
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    • v.1 no.2
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    • pp.110-119
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    • 2011
  • Numerical and experimental studies were performed to investigate the aerodynamic performance of a thin wing in close vicinity to the ground. The vortex lattice method (VLM) was utilized to simulate the wing in ground (WIG) effect, which included freely deforming wake elements. The numerical results acquired through the VLM were compared to the experimental results. The experiment entailed varying the ground clearance using the DHMTU (Department of Hydromechanics of the Marine Technical University of Saint Petersburg) wing and the WIG craft model in the wind tunnel. The aero-dynamic influence of the design parameters, such as angles of attack, aspect ratios, taper ratios, and sweep angles were studied and compared between the numerical and experimental results associated with the WIG craft. Both numerical and experimental results suggested that the endplate augments the WIG effect for a small ground clearance. In addition, the vortex lattice method simulated the wake deformation following the wing in the influence of the ground effect.

Development of a Contact Type Height Sensor to Measure Ground Clearance of an Agricultural Tractor (농용 트랙터용 접촉식 지상고 측정 센서 개발)

  • Lee, Choong-Ho;Lee, Je-Yong;Lee, Sang-Sik
    • Journal of Biosystems Engineering
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    • v.33 no.1
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    • pp.7-13
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    • 2008
  • The tillage depth control system is one of the most salient control system of tractor implements. A contact-type height sensor was developed to measure ground clearance for the tillage depth control. The height sensor was fabricated in this study, and its efficacy in a tillage depth control system was evaluated. Experiments were conducted in order to determine both static and dynamic detection characteristics of the height sensor using soil bin system on the sampled soil (sandy loam, sand, clay loam). The results of the static detection characteristics showed that in the case, sandy loam soil despite and clay loam soil at a wet basis moisture content of 30%, large measurement errors were observed a due to penetration of a plastic puck into the sampled soil. The results of the dynamic detection characteristics showed that the height sensor detected the distance from the ground of sandy loam soil despite the uneven nature of the ground surface and the changes in traveling speed $1km/h{\sim}5km/h$ at a wet basis moisture content of 10%.

A Study on the Performance of the Wing In Ground Effect by a Vortex Lattice Method (와류 격자법에 의한 지면효과익의 성능 연구)

  • Jeong, Gwang-Hyo;Jang, Jong-Hui;Jeon, Ho-Hwan
    • Journal of Ocean Engineering and Technology
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    • v.12 no.2
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    • pp.87-96
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    • 1998
  • A numerical simulation was done to investigate the performance of thin wings in close vicinity to ground. The simulation is based on Vortex Lattice Method(VLM) and freely deforming wake elements are taken into account for a sudden acceleration case. The parameters covered in the simulation are angle of attack, aspect ratio, ground clearance, sweep angle and taper ratio. In addition, the effect of the wing endplate on the ground effect is included. The wing sections used for present computations are uncambered, cambered and S-types. The present computational results are compared with other published computational results and experimental data.

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A An Experimental Study for Load Capacity and Dip Characteristic in Overhead Transmission Lines (가공송전선의 부하용량과 이도 특성에 관한 실험적 연구)

  • Kim, Sung-Duck
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.12
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    • pp.177-183
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    • 2010
  • Overhead transmission lines in domestic area have been built by several different design standards of dip and ground clearance. This paper describes an experimental study for evaluating load capacity and dip margin in overhead transmission lines. Such design standards for selection of overhead transmission conductors, dip and ground clearance, as well as electrical equipment technical standard are discussed. Based on daily load and weather data, several characteristics such as line utilization factor, load factor, conductor temperature and dip, etc. are analyzed, and compared with the specified levels of design standards. As a result, it is verified that DLR method can be a clue of the solving of the problem, for occurring in old transmission conductors which may be rarely operating below standards.

Propulsion Installation Design on Wing-Mounted-Nacelle Type (주익장착방식의 추진기관 장착설계)

  • 진광석;최광윤;공창덕
    • Journal of the Korean Society of Propulsion Engineers
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    • v.2 no.1
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    • pp.88-94
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    • 1998
  • Installation design methods and results of an aircraft engine on the wing-mounted-nacelle type aircraft has been presented in this paper. The design process starts from design requirements and constraints and covers some major aspects of the engine installation design such as wing-nacelle interference drag, roll clearance, ground clearance, nose gear collapse margin, rotor burst and fuel tank capacity. The method was applied to 100-seat class airplane(K100). Results of the design suggest optimum nacelle location and nacelle installation angle(toe-in, incidence, droop angle) which satisfies in stalled engine performance and size/location of wing dry day.

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Evaluation for Lifetime and Thermal Ratings for Aged Overhead Transmission Lines (노후 가공송전선의 수명과 열용량의 평가)

  • Kim, Sung-Duck
    • Journal of IKEEE
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    • v.16 no.1
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    • pp.1-6
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    • 2012
  • Thermal rating or lifetime evaluation for aged overhead transmission line becomes more important concerns with respect to keeping power delivery stable having proper capability. Both load rating and dip/clearance are essential factors to determine transmission capacity. In order to evaluate thermal rating and conductor lifetime for domestic transmission lines with double-circuit, the dip/ground clearance standards as well as the electrical equipment technical standard are examined. Conductor temperature and dip are calculated under the assumption of a contingency, and then, a method to up-rate load capacity is searched. As thermal rating and limit dip for aged conductor are properly evaluated, an improved strategy in order to guarantee the existing power system reliability is presented in this paper.

Hydraulic Level Control System of Combine Body (콤바인 차체의 유압 수평제어 장치에 관한 연구)

  • Lee S. S.;Mun J. H.;Park W. Y.;Lee C. H.;Lee K. S.;Hwang H.
    • Journal of Biosystems Engineering
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    • v.29 no.5
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    • pp.425-432
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    • 2004
  • In harvesting rice and barley using combine, the inclination of the body caused by the irregular surface condition of the field and the soil sinking from the unbalanced weight during the grain collection used to make harvesting operation difficult and even impossible. To overcome such a problem hydraulic system far automatic and manual leveling control of a combine has been developed. The system was composed of the combine body and the hydraulic level control system mounted on it. The maximum height of ground clearance was set up to be 290mm. And the limit angle of the leveling control was set up to be $\pm7^{\circ}$. The proposed controller and hydraulic system was implemented to the prototype combine. The prototype combine was designed and built as a separable structure with the body and the track of it. This paper shows results of a specification and design testing with the hydraulic level control system far body of combine.

A Simulation of 3-D Navigation System of the Helicopter based on TRN Using Matlab

  • Kim, Eui-Hong;Lee, Hong-Ro
    • Spatial Information Research
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    • v.15 no.4
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    • pp.363-370
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    • 2007
  • This study has been carried for the development of the basic algorithm of helicopter navigation system based on TRN (Terrain Referenced Navigation) with information input from the GPS. The helicopter determines flight path due to Origination-Destination analysis on the Cartesian coordinate system of 3-D DTM. This system shows 3-D mesh map and the O-D flight path profile for the pilot's acknowledgement of the terrain, at first. The system builds TCF (terrain clearance floor) far the buffer zone upon the surface of ground relief to avid the ground collision. If the helicopter enters to the buffer zone during navigation, the real-time warning message which commands to raise the body pops up using Matlab menu. While departing or landing, control of the height of the body is possible. At present, the information (x, y, z coordinates) from the GPS is assumed to be input into the system every 92.8 m of horizontal distance while navigating along flight path. DTM of 3" interval has been adopted from that which was provided by ChumSungDae Co., Ltd..

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Numerical study on aerodynamics of banked wing in ground effect

  • Jia, Qing;Yang, Wei;Yang, Zhigang
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.8 no.2
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    • pp.209-217
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    • 2016
  • Unlike conventional airplane, a WIG craft experiences righting moment and adverse yaw moment in banked turning in ground effect. Numerical simulations are carried out to study the aerodynamics of banked wing in ground effect. Configurations of rectangular wing and delta wing are considered, and performance of endplates and ailerons during banking are also studied. The study shows that righting moment increase nonlinearly with heeling angle, and endplates enhance the righting. The asymmetric aerodynamic distribution along span of wing with heeling angle introduces adverse yaw moment. Heeling in ground effect with small ground clearance increases the vertical aerodynamic force and makes WIG craft climb. Deflections of ailerons introduce lift decrease and a light pitching motion. Delta wing shows advantage in banked turning for smaller righting moment and adverse yaw moment during banking.

Investigation of the Downwash Induced by Rotary Wings in Ground Effect

  • Tanabe, Yasutada;Saito, Shigeru;Ooyama, Naoko;Hiraoka, Katsumi
    • International Journal of Aeronautical and Space Sciences
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    • v.10 no.1
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    • pp.20-29
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    • 2009
  • There are concerns about the influence of the gust wind caused by helicopters affecting the moving vehicles while hovering over the road during rescue activities. For the understanding of such complicated flow. numerical simulation of a rotor hovering above the ground has been carried out, changing the rotor/ground clearances. The rotor thrust is kept constant. and the rotor control is determined by trim adjustments incorporated into the CFD algorithm. Collective pitch angle and the required power decreases with the rotor/ground clearance which agrees with experience. Changes of the flowfield near the rotor with regard to the rotor height are investigated based on the calculated results.