• Title/Summary/Keyword: Magnus Rotor

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Evaluation of The Dispersion Uniformity of Footprint of The Magnus Rotor Type Dispersive Submunition (Magnus Rotor형 분산자탄 탄착군의 분산 균일도 평가)

  • Hyeongyu Sakong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.27 no.2
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    • pp.230-237
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    • 2024
  • Dispersion munitions are often equipped with dispersive submunitions used to scatter bombs over a wide area, and one of the types of dispersive submunitions is the Magnus rotor, commonly referred to as a self-rotating flying body. The Magnus rotor is designed to be dispered over a wide area by utilizing the principle of the Magnus effect through self-rotation, and has various trajectories depending on the initial conditions from the mother dispersion munition. In this paper, an index to evaluate the dispersion uniformity of footprint of the dispersive submunition is presented and the dispersion uniformity according to various initial release conditions is evaluated, and it is getting larger with high incidence angle and get max value at certain initial angular velocity.

Experimental Study on the Effects of Surface Shape and Roughness on the Magnus Effect of Rotor Sails (로터 세일의 표면 형상과 조도 변화에 따른 마그누스 효과에 관한 실험연구)

  • Young-Jin Kim;Jae-Yeun Hwang;Byoung-Kwon Ahn
    • Journal of the Society of Naval Architects of Korea
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    • v.60 no.5
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    • pp.351-357
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    • 2023
  • In this study, we devised methods to enhance the efficiency of rotor sails which have been applied as one of the energy saving devices of ships. The idea of the study originated from the notion that installing protrusions or increasing the surface roughness on the smooth surface of the rotor sail could delay the separation of the incoming wind flow and consequently increase the lift force. Five cylinder models were considered and tested in an open-type wind tunnel at Chungnam National University. A smooth surface cylinder exhibits the highest lift-to-drag ratio at a specific Reynolds number, and as the Reynolds number increases this value decreases sharply. The variation in this typical Magnus force can be significantly improved by altering the surface shape and roughness of the rotor sail. It has been observed that increasing the surface roughness improves the lift characteristics, resulting in increased efficiency. Furthermore, it revealed that the reverse Magnus effect which may occur during actual operation in the low spin ratio region can be significantly enhanced.

Quantitative Analysis of Initial Dispersion Condition Effects on Randomness of Magnus Rotor Bomblet (Magnus Rotor 자탄의 초기 방출조건이 분산도에 미치는 영향에 대한 정량적 분석)

  • Bai, Ikhyun
    • Journal of the Korea Society for Simulation
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    • v.28 no.3
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    • pp.83-89
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    • 2019
  • This research describes quantitative effects of initial dispersion conditions upon the dispersion randomness of Magnus rotor bomblets. Ratios of the missile spin rate to the missile velocity, a, flight path angles, ${\gamma}$ and altitudes, h, were changed to investigate their effects on dispersion randomness. Dispersion was analyzed through calculation of 6 degree of freedom motion equation with aerodynamic coefficients from wind tunnel experiments. In order to analyze the randomness, regression analysis is adopted to calculate the coefficient of determination. The optimized ratio of the missile spin rate to the missile velocity and flight path angle were obtained and the dispersion altitudes had more effect on the dispersion diameter and had less effect on dispersion than other parameters.

Numerical Analysis Study on the Turbulent Flow Characteristics around the Rotor Sail for Vessels (선박용 로터세일 주위의 난류 유동특성에 관한 수치해석적 연구)

  • Kim, Jung-eun;Cho, Dae-Hwan;Lee, Chang-Yong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.4
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    • pp.648-656
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    • 2022
  • As environmental regulations such as the International Maritime Organization (IMO)'s strategy to reduce greenhouse gases(GHG) are strengthened, technology development such as eco-friendly ships and alternative fuels is expanding. As part of this, ship propulsion technology using energy reduction and wind propulsion technology is emerging, especially in shipping companies and shipbuilders. By securing wind propulsion technology and introducing empirical research into shipbuilding and shipping, a high value-added market using eco-friendly technology can be created. Moreover, by reducing the fuel consumption rate of operating ships, GHG can be reduced by 6-8%. Rotor Sail (RS) technology is to generate a hydrodynamic lift in the vertical direction of the cylinder when the circular cylinder rotates at a constant speed and passes through the fluid. This is called the Magnus effect, and this study attempted to propose a plan to increase propulsion efficiency through a numerical analysis study on turbulence flow characteristics around RS, a wind power assistance propulsion system installed on a ship. Therefore, CL and CD values according to SR and AR changes were derived as parameters that affect the aerodynamic force of the RS, and the flow characteristics around the rotor sail were compared according to EP application.

A Study on the High Lifting Device Equipped with the Trailing Edge Rotor for the Enhancement of Circulation Control (뒷날에 붙인 회전자로 순환유동을 강화하는 날개장치의 성능 연구)

  • Oh, Jung-Keun;Kim, Hyo-Chul
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.4
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    • pp.533-542
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    • 2010
  • For a long times it has been believed that the Magnus effect of the rotating cylinder could be utilized for the lifting devices applicable to marine practices. It has been reported that the rotating cylinder installed on upper deck of commercial vessel could play a energy saving role however the idea might be applicable in a very rare case in ship building practices. In this study special high lift rudder system equipped with the trailing edge rotor has been suggested in correspondence with the increasing requirement of greater rudder force. Through the numerical simulation it is cleared that the trailing edge rotor could play a role in enhancement of circulation and refinement of boundary layer of the rudder system. At the same time it is found out that the lift force of the rudder system without rotation of trailing edge rotor could be doubled when the circumferential velocity of the trailing edge rotor is equal to twice of the inflow velocity.

Numerical Study on the Aerodynamic Performance of Asymmetric Vertical Folding Rotor Sail (비대칭 수직 접이식 로터세일의 성능 평가에 관한 수치해석 연구)

  • Jung Yoon Park;Janghoon Seo;Dong-Woo Park
    • Journal of the Society of Naval Architects of Korea
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    • v.61 no.2
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    • pp.68-76
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    • 2024
  • The rotor sail is one of the representative devices in eco-friendly wind-assisted propulsion systems that have been practically applied to commercial ships. The present study proposes an asymmetric vertical folding rotor sail (AFRS) designed for small ships, featuring asymmetric geometry along the vertical direction and the function of vertical folding. To evaluate the aerodynamic performance of rotor sail, the drag, lift and lift-to-drag ratio were derived using computational fluid dynamics. The aerodynamic performance of AFRS was compared with that of normal rotor sail with different aspect ratios and spin ratios. The effect of geometric parameters on the aerodynamic performance of AFRS was assessed by varying the asymmetric diameter ratio. The maximum improvement in lift-to-drag ratio for AFRS was approximately 12% in the considered case. Additionally, the resistance is decreased when AFRS is vertically folded without rotating. Throughout the present study, improved aerodynamic and resistance performances for AFRS were confirmed, which will successfully provide additional propulsion to small ships.

Numerical Study on the Effect of the Arrangement Type of Rotor Sail on Lift Formation (로터세일의 배열 형태가 양력 형성에 미치는 영향에 관한 수치해석적 연구)

  • Jung-Eun Kim;Dae-Hwan Cho;Chang-Yong Lee
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.2
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    • pp.197-206
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    • 2023
  • Recently, the international community, including the International Maritime Organization (IMO), has strengthened regulations on air pollution emissions of ships, and eco-friendly ships are actively being developed to reduce exhaust gas emissions. Among them, rotor sail (RS), a wind-assisted ship propulsion system, is attracting attention again. RS is a cylindrical device installed on the ship deck, that generates hydrodynamic lift using a magnus effect. This is a next generation eco-friendly auxiliary propulsion technology, and Enercon company, which developed RS-applied ships, announced that fuel savings of more than 30% are possible. In this study, optimal installation conditions such as RS spacing and arrangement type were selected when multiple RSs were installed on ships. AR=5.1, SR=1.0, and De/D was fixed at 2.0 according to the RS arrangement, and the wind direction was considered only for the unidirectional +y-axis. Regarding arrangement conditions, five conditions were set at 3D intervals in the +x-axis direction from 3D to 15D and five conditions in the +y-axis direction from 5D to 25D. CL, CD and aerodynamic efficiency (CL/CD) were compared according to the square(□) and diamond(◇) shape arrangements. Consequently, the effect of RS on the longitudinal distance was not significantly different. However, in the case of RS flow characteristics according to the transverse distance, the interaction effect of RS was the greatest when the two RSs almost matched the wind direction. In the case of the RS flow characteristics according to the arrangement, notably, when the wind blew in the forward (0°) direction, the diamond (◇) arrangement was least affected by the backward flow between RSs.