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Numerical Study on Resistance of Stepped Planing Hull Rayhan, Fajri Ashfi; Masrul, Andika; Khairullah Akbar, Arya; Anugerah Putra, Bima
Journal of Mechanical Engineering Science and Technology (JMEST) Vol 7, No 2 (2023)
Publisher : Universitas Negeri Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17977/um016v7i22023p106

Abstract

A stepped planing hull, also known as a step hull, is a hull modification that reduces the wetted surface area. Although this type of hull has proven effective in several ships, it is still rarely used. The step hull possesses numerous advantages that make it ideal for activities involving small and fast boats. However, regrettably, its full potential remains untapped at present. The purpose of this study was to identify the effect of variations in the angle of the step hull on resistance or drag. The study utilized the CFD method, and three hull configuration models were used at each change in hull step angle of 180º, 210º, 240º, and 270º. Configurations 1 and 2 have similarities in terms of rear hull length (600 mm), hull height (20 mm for configuration 1 and 30 mm for configuration 2), and deadrise angle (15° for configuration 1 and 20° for configuration 2). Configuration 3 has similarities with an 800 mm rear hull, 20 mm hull height, and 15° deadrise angle. It was found that as the Froude number increases, the coefficient of total resistance decreases. Conversely, as the Froude number increases, the resulting resistance also increases. The configuration with the highest resistance value corresponds to the alteration from configuration 2 with a hull step of 180°, and that the alteration from configuration 2 with a hull step of 270° corresponds to the configuration with the lowest resistance value. This study concludes that deadrise angle and the height of the step hull are the main factors that require careful consideration when designing ships that use a step hull. Therefore, this research provides an understanding of the step hull and can serve as a basis for the development of the step hull.
Analisis Efisiensi Propeler Dengan Desain Bilah Melingkar Anugerah Putra, Bima; Ashfi Rayhan, Fajri
Applied Science and Technology on Naval Engineering Vol 2 No 1 (2024): Applied Science and Technology on Naval Engineering (ASTNE)
Publisher : Fakultas Teknik UPN Veteran Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

The toroidal propeller, characterized by its circular blade shape, has gained attention for its potential benefits, including increased efficiency and reduced noise levels. Despite its advantages, limited scientific literature exists on toroidal propeller research, predominantly relying on field experiments. This study seeks to assess the toroidal propeller's performance by comparing it to a conventionally shaped propeller with similar geometric parameters. Parameters such as propeller diameter, number of blades, hub diameter, and blade front view are adjusted in the conventional propeller model to mimic the toroidal design. The pitch parameter of the conventional propeller is varied to explore its ability to match the efficiency of the toroidal propeller. Utilizing Computational Fluid Dynamics (CFD) simulations through Simscale software, propeller models are evaluated across a range of RPM (1000 - 6000). The simulations yield thrust and torque values, subsequently used to calculate efficiency. Results indicate that thrust and torque increase with higher pitch and RPM. Interestingly, a variation of the conventional propeller with a pitch of 171.45 mm demonstrates superior efficiency compared to the toroidal propeller, albeit with lower thrust. Visualization of fluid flow on each model reveals optimal flow in the toroidal propeller, devoid of vorticity. This study enhances understanding of toroidal propellers, offering insights that contribute to the ongoing development of this technology.