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.
This paper discusses the use of foil-shaped center bulb in catamaran fishing vessels, where the length, width, and height of the center bulb were configured into six variations. This study aims to get the best configuration that can most reduce the total resistance of catamaran fishing vessels. Ship resistance was tested at Fr 0.15 to Fr 0.35 using the CFD method. The results showed that the best model was found in Model 6, where the length of the center bulb was 15% greater while the width and height were smaller by 10% from the original one. Model 6 can reduce resistance by 10.68%.
The development of technology in the ship industry is remarkable with many new innovations in the effort to improve ship performances. Ship resistance is one of the aspects that is very important to be comprehended the ship's characteristics. One of the innovations to reduce ship resistance is by adding hull vane to the ship hull. Hull vane is a fixed foil placed under the water line at the stern of the ship. This study is aimed to determine the effect of ship resistance after the addition of the hull vane and the location of the hull vane on the ship hull. This study utilizes a computer application program Computational Fluid Dynamic (CFD). The foil used is NACA 2415 type with s parameters angle of attack 5°, span foil 9.76 m, and chord hull vane length 1.15 m.. Investigations are further carried out on the variation of the vane hull at 2 different positions and implementation of single foil and double foil configurations. The results of this study indicate that the installation of a single foil hull vane on a ship can reduce vessel resistance and in contrast for the installation of double foil. In the case of single foil and its position at 50% of T = 2.9 m the resistance is found to be most optimally reduced when the vessel is operated at Froude number Fr = 0.342. The reduction in the total vessel resistance is 20.135% in comparison to the ship without a hull vane.
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