• 제목/요약/키워드: Tidal flow

검색결과 487건 처리시간 0.026초

금오도-안도 협수로 해역의 조류 및 조석잔차류 특성 (Characteristics of tidal current and tidal induced residual current in the channel between Geumo Island and An Island in the southern waters of Korea)

  • 추효상
    • 수산해양기술연구
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    • 제57권3호
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    • pp.214-227
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    • 2021
  • The distribution of tidal current and tidal induced residual current, topographical eddies and tidal residual circulation in the waters surrounding the Geumo Island-An Island channel were identified through numerical model experiments and vorticity balance analysis. Tidal current flows southwest at flood and northeast at ebb along the channel. The maximum flow velocity was about 100-150 cm/s in neap and spring tide. During the flood current in the neap tide, clockwise small eddies were formed in the waters west of Sobu Island and southwest of Daebu Island, and a more grown eddy was formed in the southern waters of Geumo Island in the spring tide. A small eddy that existed in the western waters of Chosam Island during the ebb in neap tide appeared to be a more grown topographical eddy in the northeastern waters of Chosam Island in spring tide. Tidal ellipses were generally reciprocating and were almost straight in the channel. These topographical eddies are made of vorticity caused by coastal friction when tidal flow passes through the channel. They gradually grow in size as they are transported and accumulated at the end of the channel. When the current becomes stronger, the topographic eddies move, settle, spread to the outer sea and grow as a counterclockwise or clockwise tidal residual circulation depending on the surrounding terrain. In the waters surrounding the channel, there were counterclockwise small tidal residual circulations in the central part of the channel, clockwise from the northeast end of the channel to northwest inner bay of An Island, and clockwise and counterclockwise between Daebu Island and An Island. The circulation flow rate was up to 20-30 cm/s. In the future, it is necessary to conduct an experimental study to understand the growth process of the tidal residual circulation in more detail due to the convergence and divergence of seawater around the channel.

유입유동에 따른 조류터빈의 성능의 변화 (A Study on the Performance of Tidal Turbine by Inflow condition)

  • 김부기;양창조;최민선
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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    • pp.154-154
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    • 2012
  • Many suggestions is offered to resolve global warming. Tidal current generation is producing power by switched tidal difference sea water horizontal fluid flow produced by tidal difference using rotor and generator. So, change the angle of inflow condition due to the entrance of efficiency are considered. We therefore investigated three dimensional flow analysis and performance evaluation using commercial ANSYS-CFX code for horizontal axis turbine. Then We also studied three dimensional flow characteristics of a rotating rotor and blade surface streamlines around a rotor. As a result, Cp was highest at TSR 5.5, especially the larger changes in the angle of inflow condition decreased efficiency.

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조류자원의 평가에 관한 이론적 연구 (Theoretical Study on Assessment of Tidal Stream Resources)

  • 양창조
    • 해양환경안전학회지
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    • 제17권1호
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    • pp.23-28
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    • 2011
  • 조류자원을 평가하기 위해 양쪽이 무한한 바다에 연결되어 있고, 수평한 바닥을 갖고 있는 수로를 가정하고, 수위의 시간변화에 따른 동적효과를 무시한 개수로 유동에서 양 끝단의 수두 차에 의해 구동되는 단순 수로에 대해 에너지 추출 모델을 제안하였다. 조류에너지는 그 단면을 지나는 유속의 3승에 비례하며, 수로 내에서의 에너지 추출은 반드시 유속의 감소를 초래하였다. 교란되지 않는 흐름의 수로에서 10%의 에너지 추출은 약 5.7%의 유속 감속을 초래하며, 20%가 추출되면 유속은 약 11.3%로 감소되었다. 또한, 수로 내에서 더 유속 감소가 가능하다면 이용 가능한 에너지의 추출은 보다 높을 수 있음을 보였다.

3차원 수치모형을 이용한 방조제 끝막이 구간의 수리특성분석(수공) (An Analysis of Hydraulic Characteristics in Sea Dike Closure Gap Using a Three Dimensional Numerical Model)

  • 강민구;박승우;임상준
    • 한국농공학회:학술대회논문집
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    • 한국농공학회 2000년도 학술발표회 발표논문집
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    • pp.405-411
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    • 2000
  • This study reviews qualitatively the flow characteristics around th tidal gap during seadike closures using a three-dimensional model for shallow water equations. The Princeton Ocean Model(POM) was adapted and applied to the Sihwa Seadike which was closed in 1994. The simulated flow patterns around the gap showed that tidal velocities increase with the cross-sectional area during ebb tide. The accelerated flow extended to wider zones passing the gap, and shock waves were generated. Vertical tidal velocity profiles were affected as the bottom scours developed beyond normal conditions.

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조력발전과 해류발전을 겸하는 통합발전시스템 (Integrated Power System Combining Tidal Power and Ocean Current Power)

  • 장경수;이정은
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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    • pp.270-273
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    • 2008
  • The integrated power system combining a tidal power plant and two ocean current power parks is suggested. It is characterized by the set up of an ocean current power park in the lake side by installing a number of ocean current turbines generating electricity by using sea water flow discharged into the lake side from the turbine generator of a tidal power plant and an ocean current power park in the sea side by installing a number of ocean current turbines generating electricity by using sea water flow exiting into the sea side through the sluice gate from the lake side. The vision of the integrated power system is demonstrated by the simple theory and simulation results of the SIWHA Tidal Power Plant. And it is shown that the newly proposed integrated power system combining tidal power and ocean current power can produce very high economical benefits.

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조력발전소 조위 제약사항을 고려한 발전기 효율시험에 관한 연구 (A Study of a Generator Efficient Testing Method that Incorporates Tidal Limitations)

  • 김현한;전정표;김광호
    • 산업기술연구
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    • 제33권A호
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    • pp.23-30
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    • 2013
  • Tidal power generation is to produce electrical energy from fluctuations of the ebb and flow in a constructed embankment. More specifically, the sinusoidal variations of tidal flow, along with the periodicity and changes in the height of waves over time make the tidal power generation possible at a certain tidal level. This paper proposes a more practical efficiency test method for tidal power plant generator that utilizes the axis torque changing values rather than the retardation method which is commonly used. The proposed method was compared with the conventional method and the test result shows that proposed method provides a similar accuracy with the conventional retardation method and a better efficiency.

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만내의 해수유동에 관한 실험적 연구 (An Experimental Study on the Sea Water Flow in Bay)

  • 김미금;김창제
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 2002년도 춘계학술대회논문집
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    • pp.205-218
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    • 2002
  • Recently, the water pollution of coastal sea area including harbor, bay and inland sea has been very serious and it causes various environmental impacts. In this study, water flow system of Danghang Bay, which has the narrow and long topographical characteristics with the narrow bay mouth and its flow is influenced principally by the tidal current, is investigated experimentally and numerically. In order to understand the tidal system of Danghang Bay, harmonic analysis is performed based on measured tidal range and flow velocity In addition, numerical model for tidal exchange is developed considering conditions of Danghang Ray. Calculated results show good agreement with measurements. Lastly. based on the proposed numerical model, exchange ratio of seawater volume in Danghang Bay is predicted.

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수치모형을 통한 함평만과 해제반도 주변해역의 조류 및 조석잔차류 분포 (Tidal and tide-induced residual currents around Hampyung Bay and Hajae Peninsula by numerical simulation)

  • 추효상
    • 수산해양기술연구
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    • 제56권2호
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    • pp.114-125
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    • 2020
  • In order to understand the currents around Hampyung Bay and Haeje Peninsula, 2D numerical simulations for tidal currents and tide-induced residual currents were carried out. Dominant semidiurnal tidal currents have reversing form and flow NNE-SSW from northern Haeje Peninsula to Songi Island, E-S at northern Haeje Peninsula and NNW-SSE in Hampyung Bay. In flood, a part of currents from Imja Island~Nakwhol Island flow along the main stream flowing northeast at offshore region and the rest flow into Hampyung Bay flowing east along the northern coast of Haeje Peninsula. In ebb, currents from Hampyung Bay flow west along the northern coast of Haeje Peninsula and run together with the main stream flowing southeast at offshore region. The currents create an anticyclonic circulation in flood and a cyclonic circulation in ebb around Haeje Peninsula including Hampyung Bay. Tidal currents are accumulated on Doripo which located at the entrance of Hampyung Bay and show high current velocities. Tidal currents and tide induced residual currents are weak at the inside of Hampyung Bay which has narrow entrance, shallow water depth and wide intertidal zone. An anticyclonic eddy is formed around Gaksi Island as a result of tide induced residual currents. In northern coast of Haeje Peninsula, slow constant currents flow east. It is expected that a gradual change of sediment and an increase of flushing time for suspended materials are carried by tidal currents occurring in Hampyung Bay.

바지락 치패의 폐사에 관한 연구-I 간척지의 간출시에 있어서의 온도, 염분변화와 유입하천수의 지하염분에 미치는 영향 (Studies on the Natural Mortality of the Young Short Necked Clam, Tapes japonica-I. Seaonal Variation of the tidal Temperature, Sainity , and the Effect of Overflowing Fresh Water on the Subterranean Salinity of the Tidal Flat at Low Tide)

  • 최상
    • 한국동물학회지
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    • 제9권1호
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    • pp.1-6
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    • 1966
  • Frequently , large masses of the young short necked clam, Tapes japonica , die at their tidal flats in summer and this phenomenon has not been explained clearly. The purpose of the present investigation is to study the thermal condition and the chlorinity level of tidal flats in which the young clam appears to be injured. A study is also mad efor the burrowing organism in the lower layer of the esturay over which the fresh water flow during the low tide. Observation are made at five places of the tidal flat near Ikawazu Fixheries Laboratory of Tokyo University during the ebb and flow tide period of the spring tide. The diurnal and monthly changes of tidal temperatures and chlorinities are measured. Results of the study are ; 1. The surface temperature of the tidal flat increases with the ebb tide, reaches the highest between 12-14PM, and gradually decreases thereafter. The temperatures of tidal flat below 5 and 10 cm increase gradually until the flow tide reaches the surface. 2. At the spring tide in summer , the diurnal change of surface of the tidal flat temperature is very extensive ; it reaches 37-39$^{\circ}C$ in August. At the depths of 5 and 10 cm the temperature remains at 33 $^{\circ}C$ and 31$^{\circ}C$ , respectively. 3. The chlorinity of the tidal flat is higher during May through June and lower July through August, and this seems to be related to the amount of rainfall. 4. The chlorinity of the surface of tidal flat increases slightly during the ebb and flow tide periods. The observed higher chlorinity of surface of the tidal flat was 18.82% Cl. 5. At near the esturay, the fresh water that overflows the tidal flat affects the chlorinity of the surface but no such influence to the depth of the flat. 6. From above observations, it is assumed that the young short necked clam in the tidal flat could be exposed to the severe change of environmental conditions. The high temperature of the tidal flat in summer and the low chlorinity of it at flood period may be considered as the change in environment.

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