Jo, Y. (Daewoo Shipbuilding and Marine Engineering) | Choi, J. (Daewoo Shipbuilding and Marine Engineering) | Park, S. (Daewoo Shipbuilding and Marine Engineering) | Lee, J. (Daewoo Shipbuilding and Marine Engineering) | Ki, H. (Daewoo Shipbuilding and Marine Engineering) | Han, S. (Daewoo Shipbuilding and Marine Engineering)
The activities related to exploitation for oil and gas in the Arctic areas increase significantly. In order to transport increased resources in the Arctic areas, large Arctic commercial vessels such as gas carriers, oil tankers, bulk carriers, etc. are needed for mass transportation. In Arctic area, the ice load is the main factor of environmental load acting on Arctic vessel. The ice load is increased with the enlargement of vessel.
The largest Arctic commercial vessel was built by DSME in 2016. The vessel was delivered after completion of ice trial in March 2017. The size of Arctic LNG carrier is larger than any other Arctic vessels have been constructed so far. The ice load monitoring system was installed for ice load measurement and structural safety of ice navigation of this large LNG carrier.
This paper is concerned with comparison between estimated ice load for structural design and measured ice load for vessel navigation in Arctic area. Design ice load was calculated according to prescriptive rules of the Classification societies. Actual ice load during ice navigation was measured from ice load monitoring system. The arrangement of sensors in the monitoring system was determined for the precise measurement of ice induced loads acting on the hull. FE analyses were also carried out to compare between estimated ice load and measured ice load considering complex structural details in the Arctic LNG carrier.
Ships interact with the environment in several ways. The focus in this paper is on how ships interact with the wind and how this is treated in design. It is generally sufficient in most cases to model wind force as a static load. However, there may be circumstances where a more detailed description of the wind is appropriate. Some examples discussed include stability under transverse winds, aircraft flight deck operations and wind resistance. The paper summarizes key properties of the wind and recent research related to some key windship interactions. This includes discussion of the challenges and possible remedies.
International Maritime Organization (IMO)'s recent Energy Efficiency Design Index (EEDI) regulation for new ships has increased interests in ship efficiency. As a results ship added resistance is one of the key consideration in designing a highly efficient ship and many experiments and numerical methods are conducted to predict the added resistance. In this study the motion response and the added resistance of the LNG carrier in head waves were computed using the commercial computational fluid dynamics (CFD) code Star-CCM+. Unsteady Reynolds Averaged Navier-Stokes equation (RANS) was numerically solved and the volume of fluid (VOF) approach was used to simulate the flows. The wavelengths varied from half the ship length to twice the ship length and the design speed was selected for the velocity. The heave and pitch motions were calculated along with the added resistance and the wave contours were obtained. Several grid tests were conducted to achieve the converged motion and resistance values. The calculated results were compared and validated with the experimental results.
International Maritime Organizations (IMO) has released Energy Efficiency Design Index (EEDI) regulation recently. This regulation caused ship building companies to build more efficient ships and to achieve this goal, reducing added resistance became necessary. Accurate prediction of the added resistance of the ship is needed since it could give variety of information about the efficient hull shapes. As a results, predicting added resistance became one of the highly interested domain in seakeeping problems.
Traditionally, potential based numerical methods and experimental studies are applied to predict the added resistance more correctly. Seo et al. (2014) predicts the added resistance with potential based methods and Lee et al. (2016) investigated the added resistance by model tests. However, potential based methods have limitations since it has difficulty in considering the nonlinear effects and the viscosity effects. Experiments are desirable and needed, but the expenses are rather expensive than the computational methods.
Nowadays, development of computers gave rise to new field called Computational Fluid Dynamics (CFD). CFD has gained interests since it could consider nonlinear effects and viscous effects. Nonlinear effects are especially important for short wavelengths and the viscous effects are more realistic than the inviscid model. However, the computation time is still a major issue in CFD since most of the simulation still needs a lot of computation time compared to the potential based methods. Many studies have been made using CFD methods. Sadat-Hosseini et al. (2013) compared the motion and added resistance of the KVLCC2 and Tezdogan et al. (2015) estimated the added resistance of the KRISO Container Ship (KCS) by using full scale model with commercial code, Star-CCM+. Yang et al. (2015) applied Cartesian-grid-based method to the added resistance calculation. Also, Yang and Kim (2017) predicted added resistance in short waves for the hull with several different bow shapes using CFD and showed promising results.
In this study, CFD method was used to analyze the motion and the added resistance of a given ship with head sea conditions. As CFD results are very dependent on generated grids, several tests are done on mesh generations to show the convergence of the results. Also, calculated results are validated with the experimental results. Finally, wave contours and time signals obtained are shown and analyzed.
Jeong, Seong Yeob (Korea Research Institute of Ships and Ocean Engineering (KRISO)) | Kang, Kuk Jin (Korea Research Institute of Ships and Ocean Engineering (KRISO)) | Kim, Hyun-Soo (Chungnam National University) | Kim, Jung-Jooong (Seoul National University) | Roh, Myung-Il
As climate change progresses, the amount of arctic sea ice continues to decline, and open water areas expand rapidly during the summer season in the Northern Sea Route (NSR). Thus, opening the NSR could offer great possibilities for the shipping industry and shipbuilders. The NSR is navigated by merchant vessels equipped with specially strengthened hulls, which sail between Europe and Asia during the summer and autumn periods. To ensure ship safety on the NSR, a risk assessment should be conducted before the initial stages of voyage planning. The Korea Research Institute of Ships and Ocean Engineering (KRISO) has been developing a voyage planning system called the KRISO Arctic Safe Routing System (KARS). The main purpose of KARS is to ensure safe navigation, which includes optimal route planning and increasing ship energy efficiency in the NSR. In this study, the main functions of KARS were introduced and validation tests were conducted onboard the Korean icebreaker, ARAON in the East Siberian Sea. The full scale ice trial results were summarized and the possibility of applying KARS will be discussed.
The NSR stretches from the Barents Sea to the Bering Strait. It covers approximately 5,600 km of Russia's arctic shore, and this route is almost 40% shorter than that of the Suez Canal. Since 2009, the NSR has been officially open for international shipping, and The Ob River liquefied natural gas (LNG) carrier, chartered by the Gazprom Group, successfully completed in December 2012 the world's first LNG supply via the NSR. Due to rapid increases in the production of oil and natural gas and their transportation along the NSR, ships have had to maintain safe navigation and efficient voyage planning. From the ship owners' point of view, risk assessments should be conducted before the initial stages of voyage planning to ensure ship safety on the NSR.
Generally, the transit voyage via the NSR has many uncertainties, such as ice conditions, the reliability of shipping schedules, and the structural safety of ships' hulls; thus, voyages that operate in the NSR have to minimize cost, fuel, and time to maximize the safety of these vessels. In recent years, summer operations on the NSR regions have been profitable due to melting sea ice, but vessels have also been exposed to pack ice conditions. Therefore, captains and vessel crews must always pay attention to possible impact scenarios between the ship and the ice floes during voyages.
Many types of research, including studies of Arctic voyage planning, are currently underway. These studies focus mainly on the economic feasibility of Arctic shipping. Kotovirta et al. (2009) developed an ice resistance model and optimization routes for ship navigation through the entrance to the Baltic Sea. Riska and Valkonen (2014) developed a probabilistic model for ship performance calculations that can be used to assess the economic feasibility of ship designs and transport concepts. Pastusiak (2016) developed a method for route planning of vessels in the ice-covered areas on the NSR. This study took into account the procedures for the processing of information for routing passages of the vessels on the NSR.
Kwon, Chang Seop (Ship & Offshore Research Institute) | Cho, Tae Min (Ship & Offshore Research Institute) | Lee, Young Jin (Ship & Offshore Research Institute) | Kim, Hyun Joe (Ship & Offshore Research Institute) | Lee, Dong Yeon (Ship & Offshore Research Institute)
A series of sloshing model tests are carried out for an IMO Type B tank of 30K LNG bunkering vessel. Experimental results show that the maximum sloshing impact load occurs at a filling level of 25%H and waves at a 90-degree angle. Lateral sloshing is likely to occur at the bottom of the lowest stringer in filling levels close to the lowest stringer height for this Type B tank. The analysis of hot spot areas in all filling condition indicates that the sloshing impact loads are high in the vicinity of the swash bulkhead and near the filling levels. A more detailed analysis of the experimental results is presented in this paper.
It is confirmed that under a new global cap on sulphur emission set by the International Maritime Organization (IMO), vessels will be required to use fuel oil on board with a sulphur content of less than 0.50% as of January 1st 2020 against the current limitation of 3.50% (Ma, 2012). Since the first use of LNG as a ship fuel in Norway in 2000 (ÆsØ y, 2013), LNG has been increasingly adopted as marine fuel for a variety of vessels, including container ships, cruises, ferries, shuttle tankers, bulk carriers and tugboats. Traditionally, small LNG-fueled ships are fueled by means of truck-to-ship (TTS) transfers.
LNG bunkering vessels have been delivered since 2016 to provide ship-to-ship (STS) bunkering services. Table 1 summarizes the list of LNG bunkering vessels which have been delivered and will be delivered. ENGIE at Belgium took the delivery of the world's first 5,100 cubic meters LNG bunkering vessel (Park, 2018). Shell, a giant energy company, plans to provide LNG bunkering services to large container ships, cruise ships and shuttle tankers using 6,500 cubic meters LNG bunkering vessels. Up until now, all the bunkering vessels are equipped with an IMO independent Type C tank, which has size restriction.
Table 2 indicates the expected capacity and optimal number of LNG bunkering vessels at each port of Busan, Singapore and Rotterdam (Lee, 2017). It shows that a large number of 20,000 cubic meters LNG bunkering vessels would be required. In the case of large container ships, the storage capacity of LNG fuel above 18,000 cubic meters is required for ocean voyage. Recently, membrane type tanks have been applied to large capacity LNG bunkering vessels; however, the risk of sloshing is still high. In this regard, the IMO Type B tanks can be an alternative to overcome the capacity limit of conventional Type C tanks and the risk of sloshing of membrane tanks.
Yu, Tongqiang (Jiangsu University of Science and Technology) | Liu, Kun (Jiangsu University of Science and Technology) | Wang, Qingfeng (Jiangsu University of Science and Technology) | Wang, Jiaxia (Jiangsu University of Science and Technology)
The fully opening of the northern shipping line puts forward a great challenge for the safety of polar ships, the presence of floating ice and icebergs increases the possibility of collision between ship and sea ice. However, due to the complex mechanical properties of sea ice, a reasonable description of its material constitutive relation is the main factor affecting the accusation of calculation and analysis.
In this paper, a constitutive model of ice material considering the effect of temperature is presented, a user-defined subroutine is developed and embedded into the finite element software LS-DYNA. The experimental and numerical studies of marine steel are carried out. Based on this, the collision scenario is established, the damage and deformation characteristics of the ship structure and ice are studied, The effects of collision scenario parameters are discussed. The results of this paper can provide reference for the design and manufacture of polar ships.
Arctic sea ice, especially summer sea ice, is declining at a rate of 10% every ten years (Richter M J, 2008a). The fully opening of the Arctic sea lanes is becoming possible and the polar shipping industry is bound to boom. However, due to the complicated environmental features in polar water, the strength of ships in polar waters is gaining more and more attention due to numerous ice floe and icebergs even in summer. Ship-ice collision will cause damage to ships, water or even sink and other consequences, bringing about significant loss of life and property. Therefore, the research on the collision performance of polar ships is essential to reduce the accident loss of polar ice collision and as well as the design of polar ships.
A reasonable description of sea ice's material properties plagued the scholars for years, the main obstacles are its various components and random inherent effects. Dozens of studies has been done in this area (Paige R A, 1967; Peyton H R, 1968; Timco G W, 2010). Full scale real ship-ice collision tests or ship model tests are also carried out in order to study the loading force during the collision process (Ritch R, 2008b; Valanto, 2001c). These results is available in deducing empirical formulas and analytical equations. For example, Dempsey (2001a) and Ian J. Jordaan (2001c) proposed the analytical methods for ice loading and ice pressure calculation and pointed out that sea ice had a clear scale effect. Frederking R. (2011b) studied the effect of strain rate on ice loading through comparative experiments. In recent years, with the rapid development of computer simulation technology, commercial finite element analysis software is increasingly used to simulate sea ice material and ice load as a more concise and effective way. Many material constitutive models are modified or justified to describe the iteration between the structure and sea ice reasonably(Gagnon, 2006a; Shunying Ji, 2002; Carney, 2006b ). Among them, crushable foam materials is widely accepted as for its rationality to reflect the brittleness of ice and good consistency with the experiment, but it does not have physical definitions as well as neglects the impact of damage. Other material constitutive models like Viscouselastic- plastic, elastic-plastic, and elastic-brittle sea ice material(Liu, 2012; Derradji, 2000a; Derradji, 2001b) are also detruded by different scholar in accordance with their focus point and research content.
Zhang, Yunlei (Wuhan University of Technology, Hubei Key Laboratory of Inland Shipping Technology) | Xu, Yanmin (Wuhan University of Technology, Hubei Key Laboratory of Inland Shipping Technology) | Zou, Chunming (Wuhan University of Technology, Hubei Key Laboratory of Inland Shipping Technology) | Zhao, Junchao (Wuhan University of Technology, Hubei Key Laboratory of Inland Shipping Technology) | Wang, Jianyu (Wuhan University of Technology, Hubei Key Laboratory of Inland Shipping Technology)
The paper comparatively analyzes the existing research on the longitudinal safety spacing of ships, summarizes their respective characteristics and finds the model of longitudinal safety spacing more suitable for VLCC. Based on the interference degree of VLCC, it establishes general interference model of hydrodynamic force of VLCC and calculates the minimum interferential clearance between two ships in accordance with the interference model. Consequently, it will confirm the transversal safety spacing required to be maintained in the course of encountering or overtaking. On the basis of composition and influence factors of under keel clearance(UKC), it constructs calculation models for safe UKC of VLCC of different types under various sea conditions and different loading situation by means of the analytical and semi-empirical formulas on account of dynamic subsidence calculation and comprehensive measurement of ship. So the paper establishes the three-dimensional safety domain model of VLCC by synthesizing the above three aspects, which will benefit to make full use of loading capacity of the ship and improve the utilization ratio of the channel resources. By comparison and analysis, the model has obvious advantages in the researches on safety domain of VLCC and has remarkable practical significance.
With the recovery of the world economy and the development of the shipping industry, the trend of large-scale, high-speed, specialized, and intelligent ships has become increasingly evident, especially the oil tankers, bulk carriers, and container ships. With the implementation of the ocean power strategy, a large number of large-scale ports in China's coastal areas have been completed and put into operation, and a great number of large ships are entering and leaving China's coastal regions which also has promoted the prosperity of China's shipping industry. However, huge potential threat is hidden under the prosperous shipping industry. The frequent entry and exit of large tankers out of China's coastal waters have a major impact on the existing navigational orders, large-scale ships have frequent water traffic accidents. Therefore, the research on navigation safety assurance technology for VLCC is of crucial importance to the development of the shipping industry.
Oh, Semyun (Samsung Heavy industries, Ltd.) | Kang, Daeyoul (Samsung Heavy industries, Ltd.) | Choi, Soonho (Samsung Heavy industries, Ltd.) | Lee, Dong Yeon (Samsung Heavy industries, Ltd.) | Kim, Booki (Samsung Heavy industries, Ltd.)
Recently, demands for reduction of added resistance by marine environment on ships are rapidly increasing in many shipping and/or shipbuilding companies to reduce operational cost and prepare regulations on the reduction of the greenhouse gas emission and enlarging CO2 emissions trading market. A fundamental step to minimizing added resistance is to estimate the vessel’s added resistance appropriately. Therefore, the precise prediction of added resistance is of great importance for developing the high efficient and low fuel consuming vessel. The added resistance of ships is mainly caused by wind and waves. The wind resistance becomes more prominent in containership, tanker and LNG Carrier. In estimating added resistance due to wind, it is crucial to understand their characteristics and consider their corresponding effects accurately on the powering performance of a ship. Therefore wind measurement and correction have to be carefully carried out for accurate assessment of ship’s speed performance.
In the shipping industry, there has been a growing awareness of weather effects on evaluating the powering performance of commercial ships since the EEDI has become mandatory technical measure for new ships by IMO. Estimation of the wind effect is important for the powering performance analysis and calculation of economical cost for energy efficient operation of the ships.
Ships meet various external forces during speed trials at sea caused by environmental conditions such as wind, waves, current, water depth, air temperature and water temperatures. For very large commercial ships the small wave height produces a negligible effect when compared to the added resistance caused by the wind (Fujiwara-Ueno and Ikeda, 2006). During speed trials, it is common that the wind speed and directions change significantly. Therefore, accurate and reliable onboard measurement of the wind speed and direction is essential for the evaluation of the wind resistance.
In this study, a number of wind measurements on foremast and radar mast for large container vessel, tanker and LNG carrier were performed during the sea trials. Also, the ultrasonic anemometer in addition to the ship’s own anemometer was installed on radar mast to check the measurement quality from the different anemometers. Based on these measurements, the important wind parameters are investigated, such as the influence of the wind measurement locations, the characteristics of relative wind direction depending on ship headings, and fluctuation of true wind direction.
Tian, Zhe (Ocean University of China) | Lai, Qinghao (Ocean University of China) | Li, Wei (Powerchina Huadong Engineering Corporation Limited) | Li, Zhixiong (Ocean University of China) | He, Wentao (Ocean University of China) | Liu, Guijie (Ocean University of China)
In recent years, with the increasing of the ship size, the ship propulsion should transfer more torque and thrust than before to guarantee the normal operation during the ship navigation which could cause severe vibration of the shaft. For the large vessels, the ship hull is always regarded as a thin walled cavity. Effected by the wave pressure, temperature, stormy waves, streams, the intrinsic materials properties, it easily causes dynamic response of the ship such as heaving, pitching, rolling, heeling. As a result, the hull could be deformed randomly and nonlinearly. Moreover, the deformation of large ship hull changes the position of the bearings which means that the bearings could endure unbalanced supporting forces and be worn dramatically. Meanwhile, due to these unbalanced forces, the propulsion shaft would have a great vibration which could reduce the stability and reliability of the ships propulsion system and threaten the safety of the ship navigation. Therefore, this paper focuses on the vibration characteristics of the ship propulsion shaft excited by the hull deformation. An experimental test of real ship for the shaft propulsion is taken. During the navigation of the large vessel from Yangshan port to Xin port and from Xin port to Fuqing Port, several sensors are used to collect the data from ship hull and shaft propulsion system. Based on the experimental study, several vibration characteristics of the shaft are concluded as well as some suggestions to improve the reliability and safety of the ship operating system.
The development of large vessels such as the VLCC, VLOC, containerships has a great effect on the world trade transportation. It improves the operational efficiency and economy benefits. At the same time, the breakthrough of manufacturing technologies to build the large vessels and its supporting equipment make a great progress in the advanced shipbuilding field. However, the high loss caused by mechanical failure during the operation for large vessels should be paid much more attention. Based on the statistics about 1,484 large vessels from the Swedish Club (Main engine damage study, 2012), the average cost per machinery claim had risen from USD 323,000 to USD 519,000 from 2005 to 2011. During these period, the main engine and propulsion damage contribute more than 55% of total hull and machinery claims cost. As a result, the investigation on the characteristics of the propulsion system of large vessels is quite meaningful to reduce the failure and improve the economy.
Kim, Kwang-Soo (Korea Research Institute of Ships & Ocean Engineering) | Kim, Yoo-Chul (Korea Research Institute of Ships & Ocean Engineering) | Kim, Yoonsik (Korea Research Institute of Ships & Ocean Engineering) | Kim, Jin (Korea Research Institute of Ships & Ocean Engineering) | Van, Suak-Ho (Korea Research Institute of Ships & Ocean Engineering)
One of the aims of the present work is to investigate the feasibility of the numerical predictions for the open water characteristics of the propellers in various types of vessels by using RANS solver. WAVIS 2.2 is extended to calculate the flows around a propeller in open water conditions. The grid convergence test is performed on DTMB P4119 propeller. The computational results, thrust and torque coefficients (KT and Kq) are compared with the experimental data at a wide range of advance coefficient. The target propellers are KP505 of KCS (KRISO Container Ship), KP458 of KVLCC2 (KRISO tanker), and KP632 of KLNG (KRISO LNG carrier). Another aim of this work is to investigate the effects of the open water test set-up at the towing tank, such as free surface, propeller submerged depth, and the shaft housing. The direct calculation of the open water performances for the full scale propeller is also performed and compared with the scale effect corrections by empirical formula from ITTC procedure. The feasibility and some possible deficiencies of the present RANS methods are discussed.
Propeller Open water tests are performed in towing tank to obtain the open water characteristics of a propeller. These characteristics are used in the analysis of the propulsion tests and the estimation of the required power. Concerning the numerical prediction of the propeller open water performances, the potential based methods, such as lifting surface methods, panel methods, and etc., still represent a standard for propeller flow analysis at the design condition. The results obtained from this approach can be considered enough accurate to be employed for propeller design (Kim et al., 2005). However, off-design conditions are sometimes a more challenging task for a potential based approach. So, many researchers have an endeavor to solve the RANS equations to predict the performances of a propeller, though still requiring higher computational times and resources. Especially, since the 22nd ITTC Workshop on Propeller RANS/Panel Methods and the 22nd ITTC Propulsion Committee (Gindroz et al., 1999), many studies have been published of RANS simulations to predict flow around a propeller in open water conditions (Rhee et al., 2003; Kulczyk et al., 2007; Gaggero et al., 2010; Carrica et al., 2010; Castro et al., 2011; Choi, 2014).