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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
International Journal of Naval Architecture and Ocean Engineering
Journal Basic Information
Journal DOI :
The Society of Naval Architects of Korea
Editor in Chief :
Volume & Issues
Volume 5, Issue 4 - Dec 2013
Volume 5, Issue 3 - Sep 2013
Volume 5, Issue 2 - Jun 2013
Volume 5, Issue 1 - Mar 2013
Selecting the target year
Internal modifications to reduce pollutant emissions from marine engines. A numerical approach
Lamas, M.I. ; Rodriguez, C.G. ; Rodriguez, J.D. ; Telmo, J. ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 493~501
DOI : 10.2478/IJNAOE-2013-0148
Taking into account the increasingly stringent legislation on emissions from marine engines, this work aims to analyze several internal engine modifications to reduce
(nitrogen oxides) and other pollutants. To this end, a numerical model was employed to simulate the operation cycle and characterize the exhaust gas composition. After a preliminary validation process was carried out using experimental data from a four-stroke, medium-speed marine engine, the numerical model was employed to study the influence of several internal modifications, such as water addition from 0 to 100% water to fuel ratios, exhaust gas recirculation from 0 to 100% EGR rates, modification of the overlap timing from 60 to
, modification of the intake valve closing from 510 to
, and modification of the cooling water temperature from 70 to
was reduced by nearly 100%. As expected, it was found that, by lowering the combustion temperature, there is a notable reduction in
, but an increase in CO (carbon monoxide), HC (hydrocarbons) and consumption.
RANS simulation of cavitation and hull pressure fluctuation for marine propeller operating behind-hull condition
Paik, Kwang-Jun ; Park, Hyung-Gil ; Seo, Jongsoo ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 502~512
DOI : 10.2478/IJNAOE-2013-0149
Simulations of cavitation flow and hull pressure fluctuation for a marine propeller operating behind a hull using the unsteady Reynolds-Averaged Navier-Stokes equations (RANS) are presented. A full hull body submerged under the free surface is modeled in the computational domain to simulate directly the wake field of the ship at the propeller plane. Simulations are performed in design and ballast draught conditions to study the effect of cavitation number. And two propellers with slightly different geometry are simulated to validate the detectability of the numerical simulation. All simulations are performed using a commercial CFD software FLUENT. Cavitation patterns of the simulations show good agreement with the experimental results carried out in Samsung CAvitation Tunnel (SCAT). The simulation results for the hull pressure fluctuation induced by a propeller are also compared with the experimental results showing good agreement in the tendency and amplitude, especially, for the first blade frequency.
Fully nonlinear time-domain simulation of a backward bent duct buoy floating wave energy converter using an acceleration potential method
Lee, Kyoung-Rok ; Koo, Weoncheol ; Kim, Moo-Hyun ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 513~528
DOI : 10.2478/IJNAOE-2013-0150
A floating Oscillating Water Column (OWC) wave energy converter, a Backward Bent Duct Buoy (BBDB), was simulated using a state-of-the-art, two-dimensional, fully-nonlinear Numerical Wave Tank (NWT) technique. The hydrodynamic performance of the floating OWC device was evaluated in the time domain. The acceleration potential method, with a full-updated kernel matrix calculation associated with a mode decomposition scheme, was implemented to obtain accurate estimates of the hydrodynamic force and displacement of a freely floating BBDB. The developed NWT was based on the potential theory and the boundary element method with constant panels on the boundaries. The mixed Eulerian-Lagrangian (MEL) approach was employed to capture the nonlinear free surfaces inside the chamber that interacted with a pneumatic pressure, induced by the time-varying airflow velocity at the air duct. A special viscous damping was applied to the chamber free surface to represent the viscous energy loss due to the BBDB's shape and motions. The viscous damping coefficient was properly selected using a comparison of the experimental data. The calculated surface elevation, inside and outside the chamber, with a tuned viscous damping correlated reasonably well with the experimental data for various incident wave conditions. The conservation of the total wave energy in the computational domain was confirmed over the entire range of wave frequencies.
Thermodynamic analysis of a combined gas turbine power plant with a solid oxide fuel cell for marine applications
Welaya, Yousri M.A. ; Mosleh, M. ; Ammar, Nader R. ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 529~545
DOI : 10.2478/IJNAOE-2013-0151
Strong restrictions on emissions from marine power plants (particularly
) will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC) and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heat-recovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.
Numerical analysis of sheet cavitation on marine propellers, considering the effect of cross flow
Yari, Ehsan ; Ghassemi, Hassan ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 546~558
DOI : 10.2478/IJNAOE-2013-0152
The research performed in this paper was carried out to investigate the numerical analysis of the sheet cavitation on marine propeller. The method is boundary element method (BEM). Using the Green's theorem, the velocity potential is expressed as an integral equation on the surface of the propeller by hyperboloid-shaped elements. Employing the boundary conditions, the potential is determined via solving the resulting system of equations. For the case study, a DTMB4119 propeller is analyzed with and without cavitating conditions. The pressure distribution and hydrodynamic performance curves of the propellers as well as cavity thickness obtained by numerical method are calculated and compared by the experimental results. Specifically in this article cavitation changes are investigate in both the radial and chord direction. Thus, cross flow variation has been studied in the formation and growth of sheet cavitation. According to the data obtained it can be seen that there is a better agreement and less error between the numerical results gained from the present method and Fluent results than Hong Sun method. This confirms the accurate estimation of the detachment point and the cavity change in radial direction.
Environmental analysis of present and future fuels in 2D simple model marine gas tubines
El Gohary, M. Morsy ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 559~568
DOI : 10.2478/IJNAOE-2013-0153
Increased worldwide concerns about fossil fuel costs and effects on the environment lead many governments and scientific societies to consider the hydrogen as the fuel of the future. Many researches have been made to assess the suitability of using the hydrogen gas as fuel for internal combustion engines and gas turbines; this suitability was assessed from several viewpoints including the combustion characteristics, the fuel production and storage and also the thermodynamic cycle changes with the application of hydrogen instead of ordinary fossil fuels. This paper introduces the basic environmental differences happening when changing the fuel of a marine gas turbine from marine diesel fuel to gaseous hydrogen for the same power output. Environmentally, the hydrogen is the best when the
emissions are considered, zero carbon dioxide emissions can be theoretically attained. But when the
emissions are considered, the hydrogen is not the best based on the unit heat input. The hydrogen produces 270% more
than the diesel case without any control measures. This is primarily due to the increased air flow rate bringing more nitrogen into the combustion chamber and the increased combustion temperature (10% more than the diesel case). Efficient and of course expensive
control measures are a must to control these emissions levels.
Experimental study on the method of estimating the vertical design wave force acting on a submerged dual horizontal plate
Kweon, Hyuck-Min ; Oh, Sang-Ho ; Choi, Young-Hwan ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 569~579
DOI : 10.2478/IJNAOE-2013-0154
A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005), and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011) proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011), and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011) was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974) that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011). The method of Kweon (2011) was already verified in the real sea test of Kweon et al. (2012), where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011) can be satisfactorily used for estimating the uplift force of a pile.
An experimental study on fatigue performance of cryogenic metallic materials for IMO type B tank
Lee, Jin-Sung ; You, Won-Hyo ; Yoo, Chang-Hyuk ; Kim, Kyung-Su ; Kim, Yooil ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 580~597
DOI : 10.2478/IJNAOE-2013-0155
Three materials SUS304, 9% Ni steel and Al 5083-O alloy, which are considered possible candidate for International Maritime Organization (IMO) type B Cargo Containment System, were studied. Monotonic tensile, fatigue, fatigue crack growth rate and Crack Tip Opening Displacement tests were carried out at room, intermediate low (
) and cryogenic (
) temperatures. The initial yield and tensile strengths of all materials tended to increase with decreasing temperature, whereas the change in elastic modulus was not as remarkable. The largest and smallest improvement ratio of the initial yield strengths due to a temperature reduction were observed in the SUS304 and Al 5083-O alloy, respectively. The fatigue strengths of the three materials increased with decreasing temperature. The largest increase in fatigue strength was observed in the Al 5083-O alloy, whereas the 9% Ni steel sample showed the smallest increase. In the fatigue crack growth rate test, SUS304 and Al 5083-O alloy showed a decrease in the crack propagation rate, due to decrease in temperature, but no visible improvement in da/dN was observed in the case of 9% Ni steel. In the Crack Tip Opening Displacement (CTOD) test, CTOD values were converted to critical crack length for the comparison with different thickness specimens. The critical crack length tended to decrease in the case of SUS304 and increase for the Al 5083-O alloy with decreasing temperature. In case of 9% Ni steel, change of critical crack length was not observed due to temperature decrease. In addition, the changing material properties according to the temperature of the LNG tank were analyzed according to the international code for the construction and equipment of ships carrying liquefied gases in bulk (IGC code) and the rules of classifications.
An optimum design of on-bottom stability of offshore pipelines on soft clay
Yu, Su Young ; Choi, Han Suk ; Lee, Seung Keon ; Do, Chang Ho ; Kim, Do Kyun ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 598~613
DOI : 10.2478/IJNAOE-2013-0156
This paper deals with the dynamic effect of pipeline installation and embedment for the on-bottom stability design of offshore pipelines on soft clay. On-bottom stability analysis of offshore pipelines on soft clay by DNV-RP-F109 (DNV, 2010) results in very unreasonable pipe embedment and concrete coating thickness. Thus, a new procedure of the on-bottom stability analysis was established considering dynamic effects of pipeline installation and pipe-soil interaction at touchdown point (TDP). This analysis procedure is composed of three steps: global pipeline installation analysis, local analysis at TDP, modified on-bottom stability analysis using DNV-RP-F109. Data obtained from the dynamic pipeline installation analysis were utilized for the finite element analysis (FEA) of the pipeline embedment using the non-linear soil property. From the analysis results of the proposed procedure, an optimum design of on-bottom stability of offshore pipeline on soft clay can be achieved. This procedure and result will be useful to assess the on-bottom stability analysis of offshore pipelines on soft clay. The analysis results were justified by an offshore field inspection.
Heaving displacement amplification characteristics of a power buoy in shoaling water with insufficient draft
Kweon, Hyuck-Min ; Cho, Il-Hyoung ; Cho, Hong-Yeon ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 614~624
DOI : 10.2478/IJNAOE-2013-0157
The resonance power buoy is a convincing tool that can increase the extraction efficiency of wave energy. The buoy needs a corresponding draft, to move in resonance with waves within the peak frequency band where wave energy is concentrated. However, it must still be clarified if the buoy acts as an effective displacement amplifier, when there is insufficient water depth. In this study, the vertical displacement of a circular cylinder-type buoy was calculated, with the spectrum data observed in a real shallow sea as the external wave force, and with the corresponding draft, according to the mode frequency of normal waves. Such numerical investigation result, without considering Power Take-Off (PTO) damping, confirmed that the area of the heave responses spectrum can be amplified by up to about tenfold, compared with the wave energy spectrum, if the draft corresponds to the peak frequency, even with insufficient water depth. Moreover, the amplification factor of the buoy varied, according to the seasonal changes in the wave spectra.
Conceptual design and numerical simulations of a vertical axis water turbine used for underwater mooring platforms
Wenlong, Tian ; Baowei, Song ; Zhaoyong, Mao ;
International Journal of Naval Architecture and Ocean Engineering, volume 5, issue 4, 2013, Pages 625~634
DOI : 10.2478/IJNAOE-2013-0158
Energy is a direct restriction to the working life of an underwater mooring platform (UMP). In this paper, a vertical axis water turbine (VAWT) is designed to supply energy for UMPs. The VAWT has several controlled blades, which can be opened or closed by inside plunger pumps. Two-dimensional transient numerical studies are presented to determine the operating performance and power output of the turbine under low ocean current velocity. A standard k-
turbulence model is used to perform the transient simulations. The influence of structural parameters, including foil section profile, foil chord length and rotor diameter, on the turbine performance are investigated over a range of tip-speed-ratios (TSRs). It was found that turbine with three unit length NACA0015 foils generated a maximum averaged coefficient of power, 0.1, at TSR = 2.