• Title/Summary/Keyword: 선수파

Search Result 79, Processing Time 0.021 seconds

선수 부가물 길이에 따른 Axe Bow선형의 규칙파 중 Spray억제에 관한 수치해석 연구

  • Park, Geun-Hong;Kim, Sang-Won;Jo, Dae-Hwan;Seo, Gwang-Cheol;Lee, Gyeong-U
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • 2017.11a
    • /
    • pp.238-240
    • /
    • 2017
  • 파랑 중 선수파의 영향을 줄이기 위해 도입된 Axe Bow선형은 파랑 중 항해 시 선수부에 과도한 Spray현상이 발생한다. 이를 억제하고자 선수 부가물이 도입되었으나, 수치해석적 연구가 필요할 것으로 판단하였다. 선수 부가물은 Spray rail에서 착안하였으며, 구현이 쉽고 설계 파라미터를 제시 할 수 있는 Barge형상으로 적용하였다. 본 연구에서는 선수 부가물의 길이 변화에 따른 Axe Bow 선형의 Spray 억제를 수치해석적으로 고찰하였다.

  • PDF

A Study on the Effect of Hull Appendages of High-Speed Catamarans with Modified-reverse bow on the Running Performance (반전형 선수부 형상을 갖는 고속 쌍동선의 부가물이 주행성능에 미치는 영향에 관한 연구)

  • Kim, Do-jung;Na, Hyun-ho;Kim, Jung-eun;Oh, Do-won;Choi, Hong-sik
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.25 no.5
    • /
    • pp.601-608
    • /
    • 2019
  • In this study, the effect of hull appendages on the high-speed catamarans with reverse bow shapes is compared and analyzed by numerical analysis and circulating water tank model test. The reverse bow shape showed an improved wave shape by shifting the generation position of forward divergent wave to the stern direction and was effective in resistance and stable running posture (Kim et al., 2019). In the model test results of the running performance as the wave patterns and the change of the running posture due to the fin fitted with the inner side of the inverted bow and the interceptor, 1) Trim characteristics of the inverted bow 2) Improvement of superposition of inner wave by Fin 3) The trim control by the fin and the interceptor is considered to be effective in reducing the impact of the two hull connection decks (wetdeck).

Study on Plunging Wave Breaking near Ship Bow (선수 주위의 플런징 쇄파 연구)

  • Koo, Bon-Guk
    • Journal of the Institute of Convergence Signal Processing
    • /
    • v.22 no.3
    • /
    • pp.122-127
    • /
    • 2021
  • Flow features near the ship bow such as wave breaking, small scale phenomena have been studied using numerical methods. In this study, the bow shaped wedge was adopted which is from previous paper [1, 2] and the conditions of simulation were Re = 1.64 × 105) and Fr = 2.93. Star CCM+, one of the commercial CFD programs has been used for the simulations. Simulation results such as wave profiles near the ship bow, shape of plunging jet, air entrainment, and wave breaking process have been compared with previous experimental and numerical studies. Overall results showed good agreements with previous studies. Profiles of bow waves showed that overturning jet has been created and broken along the wedge. Plunging wave breaking has been observed along the wedge and four components of plunging wave breaking process were shown. It is confirmed that velocity near the overturing jet significantly increased during plunging wave breaking.

KCS 선형의 파랑 중 자유항주모형시험

  • Yun, Geun-Hang;Kim, Dong-Jin;Yeo, Dong-Jin;Kim, Yeon-Gyu
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • 2018.11a
    • /
    • pp.9-11
    • /
    • 2018
  • 선박의 파랑 중 조종성능 변화를 추정하기 위하여 선박해양플랜트연구소 공학수조에서 KCS 선형의 모형선으로 파랑 중 자유항주모형시험을 수행하였다. 파향, 파고, 파장 등이 변화는 규칙파 상태에서 KCS 선형의 35도 선회시험을 수행하여 파 중 선회궤적변화를 관찰하였고, 정상선회 상태에서 속도기반 궤적밀림 지수를 계산하였다. 계산된 속도기반 궤적지수를 정수 중 초기선회 상태에 외력으로 작용하여 그 시뮬레이션 결과를 보정하고 이를 파랑 중 초기선회 성능과 비교분석하였다. 그 결과 초기 선회 중 도출되는 선회성능인 전진거리, 전술선회직경은 선수파일 경우, 모형선의 전진방향 속도 변화를 추가적으로 고려해야함을 확인하였다.

  • PDF

A Study on the Resistance Performance of Catamarans with Modified-Reverse Bow (반전형 선수부 형상을 가진 쌍동선 저항성능에 관한 연구)

  • Kim, Do-jung;Oh, Woo-jun;Kim, Jung-eun;Na, Hyun-ho;Choi, Hong-sik
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.24 no.7
    • /
    • pp.923-929
    • /
    • 2018
  • In this study, we analyzed the resistance performance and running attitude of a catamaran by numerical analysis with a conventional bow, which is generally applied, and a reverse, protruding bow. The shape of the reverse bow was compared through numerical analysis and model tests. The reverse bow shape showed an improved wave pattern by shifting the generation position of the forward divergent wave to the aft in comparison with a conventional bow shape. This effect was found to be effective in determining resistance and stable running attitude. The hull resistance improved by about 2.95 %. The comparative numerical analysis and model test for the reverse bow shape completed in this study should be useful for future hull design application.

Active Stabilization for Surge Motion of Moored Vessel in Irregular Head Waves (불규칙 선수파랑 중 계류된 선박의 전후동요 제어)

  • Lee, Sang-Do;Truong, Ngoc Cuong;Xu, Xiao;You, Sam-Sang
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.26 no.5
    • /
    • pp.437-444
    • /
    • 2020
  • This study was focused on the stabilization of surge motions of a moored vessel under irregular head seas. A two-point moored vessel shows strong non-linearity even in regular sea, owing to its inherent non-linear restoring force. A long-crested irregular wave is subjected to the vessel system, resulting in more complex nonlinear behavior of the displacement and velocities than in the case of regular waves. Sliding mode control (SMC) is implemented in the moored vessel to control both surge displacement and surge velocity. The SMC can provide a closed-loop system with performance and robustness against parameter uncertainties and disturbances; however, chattering is the main drawback for implementing SMC. The goal of minimizing the chattering and state convergence with accuracy is achieved using a quasi-sliding mode that approximates the discontinuous function via a continuous sigmoid function. Numerical simulations were conducted to validate the effectiveness of the proposed control algorithm.

Numerical Study on Prediction of Flare Slamming Load on Container Ship under Head Sea and Oblique Sea Conditions (선수파 및 사파조건에서 컨테이너선의 선수 플레어 슬래밍 하중 추정에 관한 수치적 연구)

  • Seo, Dae-Won;Oh, Jungkeun
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.25 no.4
    • /
    • pp.489-497
    • /
    • 2019
  • A ship operating under rough sea conditions is exposed to a slamming load due owing to its motion relative to encountered waves. In the process of reentering the water, the ship's structure is temporarily subjected to an impact pressure. In particular, bow flare slamming often occurs in large container ships with a large flare angle, and can cause structural damage. Numerical simulations were performed in this study, and the results were compared with reliable experimental results. The simulation results were also used to estimate the bow flare slamming pressures on a container ship under head sea and oblique sea conditions. It was found that a maximum impact pressure of 475 kPa was generated near the 0.975 station of the container ship under a head sea condition.

A Study on Motion Response of Small Fishing Vessels According to Various Tonnage in Regular Waves (소형어선의 크기에 따른 규칙파 중 운동응답 특성에 관한 연구)

  • Im, Nam-Kyun;Lee, Sang-Min
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.27 no.6
    • /
    • pp.832-838
    • /
    • 2021
  • Recently, reports of marine accidents of small fishing vessels less than 10 tons have been increasing. In this study, the characteristics of the motion response in regular waves were analyzed using computations for these ships. Small vessels less than 10 tons are classified by size and used for marine accident investigations. Therefore, the motion response analysis was performed on three small fishing vessels of different sizes. In the case of the head sea, it was confirmed that as the speed of the vessel increased in the long wavelength region, the motion responses of heave and pitch became large. The motion response of the smallest 3-ton fishing vessel was greater than that of the other sizes of fishing vessels. The maximum value of the roll motion shifted to the long wavelength region as the speed gradually increased in the bow sea, regardless of the size of the ship. In all the three small fishing vessels, it was found that the roll motion was the greatest at 15 knots, the highest speed in both bow and beam seas. When sailing in the head sea and bow sea conditions, lowering the speed is one of the effective approaches to reduce the effects of the vertical and lateral plane motions. The roll motion caused by the beam wave showed a tendency to increase rapidly only at a specific wavelength regardless of the speed and the size of the vessel. It was confirmed that the roll motion was significantly reduced with forward speed in the stern wave compared to the bow wave. As there is a specific region where the maximum value of the hull motion response appears depending on the size and speed of the ship, an operation method that can minimize the effect of this motion should be considered and implemented.

Analysis on the Pitch Response Spectra of a Catamaran with Bulb (벌브를 가진 쌍동형 선박의 종동요 응답 스펙트럼 분석)

  • Seo, Kwang-Cheol;Lee, Chang-Woo;Atlar, Mehmt;Lee, Gyoung-Woo;Gim, Ok-Sok
    • Journal of Navigation and Port Research
    • /
    • v.37 no.5
    • /
    • pp.481-486
    • /
    • 2013
  • In this study, a commercial seakeeping program Seakeeper, integrated into Maxsurf, which is based on the linear strip theory was employed to compare the effect of bulbous bow (with/without) on motion response characteristics in a 18-meter catamaran. The seakeeping analyses were conducted at several Beaufort wind conditions such as scale No. 3 ($\bar{T}=2.98s$, $H_{1/3}$ =0.6m), No. 4 ($\bar{T}=3.85s$, $H_{1/3}$ =1m) and No. 5 ($\bar{T}=5.44$, $H_{1/3}$ =2m) based on ITTC wave spectrum. Pitch motion response spectrum was calculated at Head sea, Head & bow sea and Beam sea as encounter angles. Hull form of a catamaran with bulb showed the maximum 20% decrease of pitch motion response as compared to that of hull form without bulb.

A Study on the Bow Wave Characteristics for the Resistance-Minimized Hull Form of Small Fishing Boat (저항최소화 소형 어선선형의 선수파 특성에 관한 연구)

  • Yu, Jin-Won;Lee, Young-Gill
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.45 no.2
    • /
    • pp.124-131
    • /
    • 2008
  • This paper presents the analysis of resistance performance and bow waves for the resistance-minimized hull form of small fishing boat by using numerical simulations and model tests. The resistance-minimized hull form is developed from an original hull form which is selected from existing small fisher boats in our country. In order to estimate the resistance performance for the original and the developed hull form, several numerical simulations and model tests are carried out. Marker and Cell(MAC) method and Marker-Density method are adopted to simulate the free-surface bow waves around advancing hull surface. The results of numerical simulations are compared with the model tests in towing tank. The results show that the resistance performance of the resistance-minimized hull form is improved than that of the original hull form. The results of this study will be a good guide to the hull form development of small fishing boats in future.