Adi Maimun

Fuzzy FMEA model for risk evaluation of ship collisions in the Malacca Strait: Based on AIS data

Maritime safety in the Malacca Strait is an important issue. The Strait of Malacca is the longest strait in the world (1120 km) and is classified as a high-risk area for navigation. The 800-km (500-mile) long Malacca Strait, linking Europe and the Middle East to the Asia-Pacific, carries about 40% of world trade. The strait is the main shipping channel between the Indian Ocean and the Pacific Ocean, linking major Asian economies such as those of India, China, Japan, and South Korea. In this paper, hazard identification and risk evaluation are established as steps of a formal safety assessment for ship collisions. The inputs of a fuzzification are obtained from a failure mode and effects analysis, which includes risk factors such as occurrence (O), severity (S), and detection (D). The risk factors O, S, and D are evaluated using the fuzzy method. The actual sea-traffic condition data are collected by means of Automatic Identification System equipment that is installed at Kobe University, Japan, and the Universiti Teknologi Malaysia (UTM) Johor, Malaysia. Those data are applied to establish the methods with the help of the Geographic Information System .

Formal Safety Assessment (FSA) for Analysis of Ship Collision Using AIS Data

Currently, maritime safety is the best issue in the world. International Maritime Organization (IMO) have recommended formal safety assessment (FSA) methodology to enhance maritime safety. In this paper, the research was conducted in the Malacca Strait. Malacca Strait is an area that has a high risk for shipping navigation. Many accidents occur in the area are like collision, fire, grounding and so on. Therefore a study on improving safety in this area is very important. It is to produce an output that can be used to provide input to the master and multiple stakeholders to improve safety on board at the time of sailing. In this study, AIS is used as a data source. Sea condition data collected actual traffic through the Automatic Identification System (AIS) equipment installed at Kobe University, Japan, and Universiti Teknologi Malaysia (UTM) in Johor, Malaysia. The data is applied to define a method with the help of Geographic Information Systems (GIS).

Static Stability and Ground Viscous Effect of a Compound Wing Configuration with Respect to Reynolds Number

Static stability is a main issue of a wing-in-ground effect (WIG) craft for safe takeoff and cruise mode of flight. In this study, the effect of ground boundary layers on aerodynamic behaviour and the height static stability of a compound wing ofWIG craft were numerically studied during ground effect. First, the principal aerodynamic coefficients of numerical analysis were validated by experimental data of the compound wing. Then, these coefficients of the compound wing were obtained for fixed and moving ground conditions. Consequently, the numerical results showed that viscous ground had some effects on lift and drag coefficients and lift-to-drag ratio, whereasmoment coefficient and centre of pressure of the compound wing had small variation due to removal of ground boundary layers.The present results clarified that the ground viscous effect can be changed slightly with Reynolds number. Also, the height static stability of the compound wing will be obtained and compared with the rectangular wing one. Based on the current results, the stability of the compound wing was higher than a common rectangular wing. In addition, the height static stability of both wings was strongly affected with ground clearance. It had slight reduction then fluctuated when Reynolds number was increased.

Design Parametric Study of a Compound Wing-in-Ground Effect. I: Aerodynamics Performance

AbstractThe configuration and service condition of a wing can influence the performance of wing-in-ground effect (WIG) craft. In this study, the aerodynamic performance of compound wings in ground effect was numerically investigated through a parametric design study. The compound wing is divided into three parts with one rectangular wing in the middle and two reverse taper wings with an anhedral angle at the sides. A NACA6409 airfoil was employed as a section of the wing. The design parameters included the span size, anhedral angle, and taper ratio plus two boundary conditions: ground clearance and Reynolds number. The three-dimensional, Reynolds-averaged Navier-Stokes (RANS) equations were solved numerically. A realizable k−e turbulent model was used to compute the effects of the turbulent flow over the wing surface. The computational results of the basic wing were compared with the experimental data of other published works. Next, the aerodynamic performance of the compound wings was computed for variou...

Hydrodynamic Resistance Reduction of Multi-Purpose Amphibious Vehicle due to Air Bubble Effect

Multipurpose Amphibious Vehicles (MAV) and other blunt shaped floating vehicles encounter the problem of a large bow wave forming and hydrodynamic resistance at high speeds. This wave formation is accompanied by higher resistance and at a critical speed results in bow submerging or swamping. Three new shapes of hull bow design for the multipurpose amphibious vehicle were conducted at several speeds to investigate the hydrodynamic phenomena using Computational Fluid Dynamics (CFD, RANS code), which is applied by Ansys-CFX14.0 and Maxsurf. The vehicle’s hydrodynamic bow shapes were able to break up induced waves and avoid swamping. Comparative results with the vehicle fitted with U-shape, V-shape and Flat-shape of hull bow, showed that the U-shape of the hull bow has reduced the total resistance to 20.3% and 13.6% compared with the V-shape and flat shape respectively. Though, the U-shape of hull bow is capable to increase the amphibious operating life and speed of vehicle. Also it has ability to reduce the vehicle’s required power, fossil fuel consumption and wetted hull surface. On the other hand, the use of air cushions to support marine vehicles, heavy floating structures and in other operation is well known. The main problem in Multi-purpose Amphibious Vehicles (MAV) is the amount of power needed in order to overcome the hydrodynamic resistance acting on the hull which is included the frictional and pressure resistances. Therefore, more power is needed to move the MAV forward. In this respect, more fuel will be required to operate the amphibious vehicles. This problem could be effectively reduced by the introduction of the air cushion concept. With the air being drawn from top of craft to the cavity below the hull will produce some cushioning effect and also help to reduce skin friction drag. In this paper, air cushion effect will be studied in rigid surface cavity instead of using flexible skirts. This would avoid the problem of high maintenance due to replacement of damaged skirts. Finally, the MAV will be supported using air cavity and bubbles generated by an air pump (compressor and air pressure vessel) to pushes the hull of multi-purpose amphibious vehicle up and reduce the frictional resistance due to draft and wetted surface reduction and layer of air between hull surface and water. This research would be done via CFD (ANSYS-CFX 14.0) and analyzed the hydrodynamic resistance

Experimental investigation of a wing-in-ground effect craft

The aerodynamic characteristics of the wing-in-ground effect (WIG) craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM) wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future.

Effect of increasing rudder deflection on rudder inflow for LNG vessel in shallow water

This paper presents the rudder inflow including fully non-uniform wake on a deep drafted LNG vessel in shallow water. The Ansys Fluent v.6.2 software was used to solve Reynold Average Navier-Stokes (RANS) equations, and Icem CFD as a mesh generator. The modeling was conducted based on the B 5-88 type propeller, with a diameter (D) of 7.7 meters. The propeller was meshed using tetra unstructured mesh in a flow field based on 3-Dimension incompressible Navier-stokes solver. It was found in the propeller-to-rudder interaction that there was a slight drop of pressure at rudder leading edge of 00 rudder angle of attack (AoA). However, the dropped pressure was observed on its leading edge as the rudder angle of attack was increased to-70. The effect of increasing rudder deflection was generated by the flow around it and inflows moved over the rudder. This deflection effect continued to X/D=0.4; afterwards, a zero velocity appeared because of the flow encountered by the stagnation region.

Design Parametric Study of a Compound Wing-in-Ground Effect. II: Aerodynamics Coefficients

The aerodynamic behavior of the wing-in-ground effect can be affected by its configuration. This configuration is potentially the most influential parameter for the performance and stability of the wing-in-ground effect craft. As a continuation to the authors’ previous works, in this research, the aerodynamic coefficients of the compound wing have been numerically investigated through the design parametric study in ground effect. The aerodynamics performances of the compound wing have been computed and the effects of various design parameters on the lift-to-drag ratio have been discussed in the previous paper. First, this paper validates the prediction method by comparing the lift coefficient of a rectangular wing with NACA 6409 airfoil for different angles of attack with an aspect ratio of 1.25 and ground clearance of 0.15. Then, the aerodynamic coefficients of the compound wing are computed over a range of various design parameters. As expected, all design parameters have effects on the aerodynamic coefficients. However, the effects of design parameters on the aerodynamic behavior of the compound wing are not equal. It was found that the span of the side wing, anhedral angle, and ground clearance have considerable effects on the ram effect pressure and the tip vortex of the compound wing.

Investigation on the dynamic stability of an underwater glider using CFD simulation

Dynamic stability is an important consideration for an underwater glider because its slow motion makes it susceptible to underwater currents. This is compounded by its weak propulsion system whereby it self-propels by shifting its net buoyancy either positive or negative during forward motion. In this paper, steady state Computational Fluid Dynamic (CFD) simulation was used to evaluate the dynamic stability of a low-speed underwater glider. Fluid domains were generated for different flow velocities and angles of attack, for both rectilinear and rotary motions. For rectilinear motion, a straight line resistance test was replicated the tow tank resistance test. For rotary motion, a rotating arm setup was replicated and various angular velocities were numerically simulated. Hydrodynamic derivatives were obtained by extracting the slopes of the lift force and moment data points. The results showed that the dynamic stability of glider improved as the velocity and mass of the glider increases.

Comparison of numerical simulation with experimental result for small scale one seater wing in ground effect (WIG) craft

In this paper, three dimensional data and behavior of incompressible and steady air flow around a small scale Wing in Ground Effect Craft (WIG) were investigated and studied numerically then compar...