A planing hull is a high-speed craft with relatively complex hydrodynamic characteristics. An increase in speed can induce a significant change in trim angle with an increment in ship drag. One solution to reduce ship resistance is to use an interceptor. This research aimed to analyze the hydrodynamics of a planing hull vessel by applying an interceptor. The fundamental aspects reviewed included the analysis of drag, trim, heave, and lift force. The interceptor would be investigated on the basis of its integrated position at its height. This research also used the computational fluid dynamic (CFD) method in calm water conditions. All simulations were conducted with the same mesh structure, which allowed the performance evaluation of the interceptor in calculating turbulent air–water flow around the ship. Numerical calculations used the Reynolds-averaged Navier–Stokes (RANS) equation with the k–ε turbulence model to predict the turbulent flow. The vertical motion of the ship was modeled using dynamic fluid–body interaction (DFBI) in the fluid domain through an overset mesh technique. The numerical approach was compared with the experimental test results of Park et al. to ensure the accuracy of the test results. The interceptor was designed at the transition phase, which showed the highest trim angle followed by high drag. The interceptor would experience negative trim at high speeds; thus, it was not recommended. The research results indicated that the most effective use of the interceptor was at Froude number 0.87 close to the chine position with a height of 100%. This interceptor could reduce a maximum of 57% drag, 17% heave, 8.48% trim, and 0.12% lift force. The interceptor could increase excessive drag and trim at Froude numbers over 1.16. The interceptor proved to be remarkably useful in trim control and ship drag reduction, but selecting the wrong dimensions and positions of the interceptor could endanger the ship. This simulation was performed on Aragon-2; thus, the interceptor performance may possibly change if a different hull geometry is used.
Drag is one of the main factors in improving fuel efficiency. Various study in regards to improve drag performance of a planing hull amongst them is a stern flap. The main parameters to design a stern flap are span length and angle of stern flap. The stern flap works by changing pressure distribution over the ship's bottom and creating a lift force on the stern transom part. This study aims to analyze the behavior of stern flap in variations of span length and angle of stern flap towards drag performance of Fridsma hull form. Finite Volume Method (FVM) and Reynolds-Averaged Navier -Stokes (RANS) are used to predict the hull resistance during simulations. Results show that shear drag is very sensitive towards the total drag value, proving that shear drag valued at least 60% of the total drag in each planing hull multi-phase characteristics phase. Stern flap with 58% of hull breadth span length installed at 0° is considered the most optimal, reducing 10.2% of total drag, followed by 18% displacement reduction. In conclusion, the stern flap effectively improves the Fridsma hull's total drag and its components on 0.89 < Fr < 1.89.
Experimental test is one of the methods for predicting drag ships using towing tank. This method has a good level of accuracy but requires quite complex equipment and costs. With the advancing technology of computing, the CFD method has emerged as an alternative for problem-solving, especially in hydrodynamics analysis. This study aims to ensure the accuracy of Computational Fluid dynamics (CFD) by verifying experimental data on high-speed vessel using an interceptor. The Interceptor system generates a hydrodynamic lift force by intercepting the flow of water under the hull. Comparison of experimental results and numerical simulations will involve analysis of drag, heave and trim. Numerical simulations were carried out using ITTC recommendations as testing standards. This research uses the grid independence study method to ensure the accuracy of the mesh. CFD simulations were carried out using the overset mesh method and the k-epsilon to solve turbulence flow. The Dynamic Fluid Body Interaction (DFBI) module is employed to resolve the dynamic motion of the ship in order to assess hull movements based on by fluid forces and moments. There can be two degrees of freedom in the heave and pitch directions. All simulations are performed in calm water condition. Verification is carried out by reviewing the condition of the ship without an interceptor and with an interceptor. 100% stroke and 60% interceptor were used as variations of the verification of this study. The results of this study indicate that the CFD analysis has been verified by the experimental method with a maximum error range of 10.7%. Planing hull is a type of fast ship that has quite complex hydrodynamic characteristics. This study also shows that the use of interceptors is proven to improve the performance of the planing hull ship.
The acting on the planing hull is the most complex hydrodynamics simulation. Therefore, an analysis was done to evaluate drag, lift force, and seakeeping in two degrees of freedom (2-DOF) which is heave and trim. It was fundamental aspects of the overall high-speed vessel. This article focused on the hydrodynamic performance of a complete interceptor configuration that could control the motion behavior of deep-V planing hull in calm water conditions. The benchmark study was undertaken by comparing numerical results with experimental study by Park at al. Models with and without interceptors had been analyzed by numerical simulation performed using Reynold Averaged Navier Stokes (RANS) to describe turbulence model with k epsilon based on computational fluid dynamic (CFD). In this study, the interceptor proper applies at a speed of less than Froude number 0.87. Interceptor reduce by 21% drag at Froude number 0.87 and also reduce by 16% trim and 6% heave at Froude number 0.58. Nevertheless, applied interceptor in high Froude number such as more than Froude number 1.16 caused interceptor lose effectiveness due to producing a decisive moment which made negative trim (bow-down) and increase total drag.
CFD is a numerical approach used to solve fluid problems. In the CFD simulation process, the meshing stage is crucial to produce high accuracy. Meshing is a process where the geometric space of an object is broken down into many nodes to translate the physical components that occur while representing the object’s physical shape. The research objective was to analyze the characteristics of the mesh technique in the Finite Volume Method (FVM) using the RANS (Reynolds - Averaged Navier - Stokes) equation. The numerical simulation approach used three mesh techniques, namely overset mesh, morphing mesh, and moving mesh. The k-ε turbulent model and VOF (Volume of Fluid) were used to model the water and air phases. The mesh technique approach in CFD simulation showed a pattern under experimental testing. This research showed the difference in value to the experimental results, namely by using the moving mesh method, the difference in resistance difference was 8% at high-speed conditions, the difference in trim value at overset mesh was 11%, and the difference in heave value with the moving mesh method was 14% at low speed. The conclusion reported that overset mesh had better than other mesh methods.
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