Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 70

Liczba wyników na stronie
first rewind previous Strona / 4 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 4 next fast forward last
EN
While operating the ship, one of the most important tasks is forecasting the ocean route. For this purpose, the speed characteristics of the ship are used, which are used in specialized computer systems and presented in publications. However, published algorithms for speed (or decrease of speed) calculations of a ship in real weather conditions on given routes are very simplified and do not contain all the relevant parameters related to the ship's hull (affecting its resistance when sailing, eg on waves), its propulsion and weather conditions. The article presents its own, more detailed mathematical model of the speed of the ship, and the performed calculations of speed of the ship were compared with the algorithms available in the literature and with the records from the ship's log.
EN
While operating the ship, one of the most important tasks is forecasting the ocean route. The vessel's speed characteristics are used to predict the route. Commonly used are very simplified algorithms for calculating those characteristics in which only a few basic ship parameters are used. The article presents a more detailed mathematical model for forecasting the speed of the ship in real weather conditions. This model requires more detailed geometric data of the ship and its propulsion (propeller and propulsion engine), but this data is available for operating ships.
EN
Ocean routes are recommended for ships based on economic criteria. Under the influence of waves. during sailing of the ship. various dangerous phenomena arise which can lead to marine crashes. Although weather sites are known to provide short-term weather forecasts (wave and wind parameters). this information is not used to calculate corrections of ocean-route guidelines. A captain based on his knowledge and experience can make such adjustments. The article presents the results of calculations of the values of dangerous parameters of phenomena which may occur during a cruise on example ocean routes. For the calculation of dangerous phenomena. the average statistical long-term (seasonal) parameters contained in weather atlas were used.
EN
Stability is one of the most important properties of the ship. The greatest influence on stability and thus on the possibility of loss of stability have the rolling of the ship on the wave. Mathematical models describing rolling on wave are complicated, and their solution, especially in the irregular wave, is only possible with numerical methods in the time domain. Large rolling, until the ship capsize, formation not only on the beam wave, but also on the following wave. Various models describing rolling (linear and nonlinear, regular and irregular wave, and constant or variable restoring moment) are presented. The predicted level hazard of stability of the ship depends on the direction of the wave and the cases where the level of hazard will be greatest.
EN
Ocean routes are recommended for ships based on economic criteria. Under the influence of waves, during the cruise of the ship, dangerous phenomena are created, the intensity of which depends on the speed of the ship and its course in relation to the direction of the waves, the state of the sea, the size of the ship, the state of loading. Although weather services are known, waves parameters are not used to calculate the value of parameters that characterize dangerous phenomena. The article presents the most frequently analysed dangerous phenomena, how they are calculated, the criteria for their evaluation, and the results of calculations for the selected vessel.
EN
During operation of the ship, fuel consumption and associated emissions are very important for economic and ecological reasons. The fuel consumption is greatly influenced by the choice of shipping route, weather conditions on these routes and engine control criteria. The article presents its own algorithm for forecasting ship operation parameters, including fuel consumption on selected shipping routes for average, statistical (seasonal) weather parameters occurring on these routes. It shows what factors have the main impact on fuel consumption and how you can affect fuel consumption during the cruise in changing weather conditions.
EN
Ocean mining systems that incorporate a single or double lift pipe are two methods used to obtain polimetallic nodules from the seabed. The pipe must be equipped with main cables and flexible pipe attached to the mining vehicle collecting nodules. While mining, the pipes in the vertical configuration are moving along with the ship above. They are subjected to currents in the water column. Such current-induced hydrodynamic drag results in a vertical deflection, which is dependent – among other factors such as varying current velocity at points along the length of the pipe. The present paper presents results of computer simulations using commercial CFD software to model the hydrodynamic forces acting on the vertical pipe of ocean mining systems. The results present the influence of the water flow direction in relation to the lift pipe on the hydrodynamic force and torsional moment acting upon the pipe.
EN
One of the methods of collecting polymetallic nodules from the sea floor is a hydraulic system using a single or double vertical pipeline. While mining, collecting pipelines suspended from a mining support vessel (MSV) move together. As a result of both the MSV’s motion with a suspended pipe system and water action (including deep-water currents) a vertical deflection and deformation occur along the pipeline. Simultaneously, stretching and bending tensions emerge along the pipeline. The article presents computer simulation results of vertical deflection and tensions within single and double vertical pipelines with fixed force from the ship’s movement (linear movement at constant speed) and regular force from the waves.
EN
During the design of the ship the most important decisions are made at the stage of preliminary design. One of the most important design parameters assumed by the ship owner is its service speed in real weather conditions occurring in the shipping line. For this speed, at the stage of preliminary design, when are known only to the basic geometric parameters of the ship and its motor power should be determined. In practice, design, power propulsion is determined with a very approximate formulas but for the speed in calm water. Only after the project contract and the signing of the contract are carried out by means of resistance and self-propulsion of model test. The article presents the concept of the method for determining the power propulsion for the assumed service speed, which depends only on the basic geometric parameters of the ship's hull.
PL
Podczas projektowania statku najważniejsze decyzje zapadają na etapie projektowania wstępnego. Jednym z najważniejszych parametrów projektowych zakładanych przez armatora statku jest jego prędkość eksploatacyjna w rzeczywistych warunkach pogodowych występujących na linii żeglugowej. Dla tej prędkości, na etapie projektowania wstępnego, gdy znane są tylko podstawowe parametry geometryczne statku, powinna być określana moc silnika napędowego. W praktyce projektowej, moc napędu określana jest z bardzo przybliżonych wzorów ale dla prędkości na wodzie spokojnej. Dopiero po wykonaniu projektu kontraktowego i podpisaniu kontraktu wykonywane są basenowe badania oporowo napędowe modelu statku. Na podstawie tych badań jest m.in. określana moc nominalna silnika napędowego oraz oszacowana jest, na podstawie dodatku żeglugowego, prędkość eksploatacyjna. W artykule przedstawiono koncepcję metody określania mocy napędu statku dla zakładanej prędkości eksploatacyjnej, uzależnionej tylko od podstawowych parametrów geometrycznych kadłuba statku.
EN
During the design of the ship the most important decisions are made at the stage of preliminary design. One of the most important design parameters assumed by the shipowner is its service speed in real weather conditions occurring in the shipping line. For this speed, at the stage of preliminary design, when are known only to the basic geometric parameters of the ship should be determined motor power. In practice design, power propulsion is determined with a very approximate formulas but for the speed in calm water. Only after the project contract and the signing of the contract are carried out by means of resistance and self-propulsion of model test. The paper presents a mathematical model for determining the power propulsion for the assumed operating speed. This model is dependent only on the basic geometric parameters of the hull of the ship and the weather parameters occurring in liner shipping. Also shows the results of calculations according to this model, the power propulsion for one of vessels built.
PL
Podczas projektowania statku najważniejsze decyzje zapadają na etapie projektowania wstępnego. Jednym z najważniejszych parametrów projektowych zakładanych przez armatora statku jest jego prędkość eksploatacyjna w rzeczywistych warunkach pogodowych występujących na linii żeglugowej. Dla tej prędkości, na etapie projektowania wstępnego, gdy znane są tylko podstawowe parametry geometryczne statku, powinna być określana moc silnika napędowego. W praktyce projektowej, moc napędu określana jest z bardzo przybliżonych wzorów ale dla prędkości na wodzie spokojnej. Dopiero po wykonaniu projektu kontraktowego i podpisaniu kontraktu wykonywane są basenowe badania oporowo-napędowe modelu statku. Na podstawie tych badań jest m.in. określana moc nominalna silnika napędowego oraz oszacowana jest, na podstawie dodatku żeglugowego, prędkość eksploatacyjna. W artykule przedstawiono matematyczny model określania mocy napędu statku dla zakładanej prędkości eksploatacyjnej. Model ten jest uzależniony tylko od podstawowych parametrów geometrycznych kadłuba statku oraz od parametrów pogodowych występujących na liniach żeglugowych. Przedstawiono także wyniki obliczeń, według tego modelu, mocy napędu dla jednego ze zbudowanych statków.
11
Content available Ship service speeds and sea margins
EN
When designing a transport vessel, one of the most important parameters assumed by the owner is the service speed of the ship. Service speed and motor power are calculated as an approximation of the ship’s speed in calm water (i.e., the contract speed) with the addition of the sea margin (SM). In current design practice, the addition of SM is not dependent on weather parameters occurring in liner shipping. This paper proposes a new method for establishing the value of SM depending on the type and size of the vessel and the average statistical weather parameters occurring on various shipping lines. The results presented in this paper clearly demonstrate that further research is needed to determine the precise relationship between the shipping and vessel type and the weather parameters on a shipping line.
PL
Podczas projektowania statku najważniejsze decyzje zapadają na etapie projektu wstępnego. Jednym z najważniejszych parametrów projektowych zakładanych przez armatora statku jest jego prędkość eksploatacyjna w rzeczywistych warunkach pogodowych występujących na linii żeglugowej. W praktyce projektowej, prędkość ta w sposób bardzo przybliżony jest oszacowana dopiero na etapie projektu technicznego po wykonaniu basenowych badań modelowych charakterystyk oporowo-napędowych projektowanego statku. Wskazane jest aby ta prędkość oraz moc napędu były już znane na etapie projektowania wstępnego. W artykule przedstawiono koncepcję modelu prędkości eksploatacyjnej przydatnej w projektowaniu wstępnym statków transportowych.
EN
During the design of the vessels the most important decisions are made at the stage of preliminary design. One of the most important design parameters assumed by the shipowner is its service speed in real weather conditions occurring in the shipping line. In design practice, this speed in a very approximate estimate is only at the stage of technical design after the basin model test. It is recommended that the speed and power of the drive were already known at the stage of preliminary design. The article presents a concept model service speed useful in the design of the preliminary cargo vessels.
PL
Podczas projektowania statku najważniejsze decyzje zapadają na etapie projektu wstępnego. Jednym z najważniejszych parametrów projektowych zakładanych przez armatora statku jest jego prędkość eksploatacyjna w rzeczywistych warunkach pogodowych występujących na linii żeglugowej. W praktyce projektowej, prędkość ta w sposób bardzo przybliżony jest oszacowana dopiero na etapie projektu technicznego po wykonaniu basenowych badań modelowych charakterystyk oporowo-napędowych projektowanego statku. Wskazane jest aby ta prędkość oraz moc napędu były już znane na etapie projektowania wstępnego. W artykule przedstawiono koncepcję modelu prędkości eksploatacyjnej przydatnej w projektowaniu wstępnym statków transportowych.
EN
During the design of the vessels the most important decisions are made at the stage of preliminary design. One of the most important design parameters assumed by the shipowner is its service speed in real weather conditions occurring in the shipping line. In design practice, this speed in a very approximate estimate is only at the stage of technical design the basin model test. It is recommended that the speed and power of the drive were already known at the stage of preliminary design. The article presents a concept model service speed useful in the design of the preliminary cargo vessels.
14
Content available Sea wind farms
EN
Wind is such an element of sea environment, from which it is relatively easy to obtain energy. Wind parameters over both seas and oceans are more favorable than those on land (due to variability of landform features). Moreover, also sea wind turbines exercise comparatively smaller negative effect on people than on land. Therefore, sea wind farms are ahead of us, as further development of wind energy. The article presents basic parameters of wind turbines, possible installations on sea bed, as well as future designs of large floating sea farms. The article presents also an example of design analyses of wind turbine, using computational fluid dynamics (CFD).
15
Content available Energy retrieval from sea waves
EN
Seas and oceans occupy approx. 71% of the Earth. On their surface wave action of stronger or weaker magnitude can be observed throughout a major part of the year. Wind-generated wave action contains energy, which can be retrieved and used for electrical current production. The paper shows what energy is contained in wind-generated waves on various ocean areas, presents dynamics of water movement in a wave as well as several examples of calculation results of the velocity of water particles and hydrodynamic pressures occurring in a wave.
16
Content available Energy retrieval from sea currents and tides
EN
Seas and oceans show variations in water levels caused by tides and continuous flow of water in the form of sea and ocean currents. Tides are most visible close to the coastline – tide parameters (water speed or change in sea level) allow construction of installations producing electric energy. Sea currents – superficial and deep are characterized by means of constant speeds and directions. Therefore energy retrieval from these elements of sea environment looks very promising. The article presents basic information on tides and currents useful for designing hydroelectric power plants. The already constructed hydroelectric power stations are also presented here together with several design solutions of future such installations.
EN
During ship design, its service speed is one of the crucial parameters that determine its future operational profitability. As sufficiently exact calculation methods applicable to preliminary design stage are lacking, the so-called contract speed, the speed a ship reaches in calm water, is usually specified during the draft stage. The service speed obtainable by a ship under real weather conditions (mainly wind and waves) is one of the most important parameters influencing a ship’s profitability on a given shipping route. This paper presents a parametric model of calculating total ship resistance on a given shipping route under actual weather conditions (wind, waves, sea current), that could be useful in the initial design of container ships.
EN
During ship design, service speed is one of the crucial parameters in determining the operational economy of the vessel. As sufficiently exact calculation methods applicable to preliminary design stage are lacking, the so-called contract speed, the speed which a ship reaches in calm water, is usually cited. Żelazny (2015) developed a parametric method for calculating total ship resistance under actual weather conditions (wind, waves, sea current). This paper presents a parametric model of a ship’s propulsion system (screw propeller – propulsion engine) as well as a method, based on both the resistance and propulsion system models, of calculating the mean statistical value of a ship’s service speed under the seasonal weather conditions occurring on shipping lines. The method makes use only of basic design parameters, and may be applied in preliminary design phase of container ships.
EN
To forecast the optimum route passage of a vessel in the real weather conditions using the so-called velocity characteristics of the ship. These are developed in the way, as to have a very simple form, which can not guarantee high precision in calculating the speed of the vessel. The paper presents a mathematical model of the external forces operating in the vessel and the algorithm to solve this model for calculating the instantaneous speed of the vessel in the selected weather conditions. Made of a computer program, after appropriate research and testing, can be used to optimize the transport route of the ship.
EN
Optimising the ship route is one of the most important tasks related to the operation of the vessel, its safety, and economic aspects of transport. Nevertheless, from a mathematical point of view, this problem has not been solved yet sufficiently precisely due to very high complexity of the model to be used to describe the motion of the ship along the shipping line, and time- and space-dependent average values of statistical weather parameters recorded during ship sailing. That is why various approximate methods are used, which, among other procedures, utilize ship speed characteristics, having the form of very simple relations between basic dimensions of the ship and the expected speed decrease at the assumed weather parameters. The paper presents a new method of calculating the speed decrease depending on technical and operating parameters of a given vessel. A computer code prepared based on this method is used for research on forecasting ship speed in real weather conditions.
first rewind previous Strona / 4 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.