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All Journal Teknomekanik Journal of Engineering Researcher and Lecturer
Budi Syahri
Department of Mechanical Engineering, Faculty of Engineering, Universitas Negeri Padang, Indonesia
Chemical Engineering, Chemistry & Bioengineering Education Engineering Mechanical Engineering

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Hydrodynamic optimization of a Sweptback Stern Foil for resistance reduction in flat-hull ships: A CFD-based extension of the Hull Vane concept Rahmat Azis Nabawi; Budi Syahri; Yogi Dian Alfana; Donny Fernandez
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.54872

Abstract

Flat-hull ships are known to have higher resistance than streamlined hulls. Although the Hull Vane® concept has been proven effective as a stern-mounted energy-saving device through pressure-field modification and stern-wave interaction, most previous studies have focused on straight-foil configurations (straight planform). The effect of planform shape optimization, particularly the sweptback configuration, on the hydrodynamic performance of flat-hull ships is limited in the literature. This study modifies the geometry of a Hull Vane® into a sweptback stern foil and evaluates its performance using Computational Fluid Dynamics simulations. The results show that a 15° sweptback angle yields the greatest reduction in total drag. Velocity contour analysis shows a narrower wake and a more uniform velocity-gradient distribution in the stern area for the 15° swept-back stern-foil configuration compared to other configurations. Meanwhile, the turbulence length distribution shows a tendency toward reduced intensity of large-scale turbulent structures behind the ship, indicating improved wake-flow characteristics. The identified drag reduction mechanism primarily stems from improved pressure recovery and modified pressure distribution in the stern area, which is consistent with the working principle of Hull Vane®. Optimizing the sweptback planform geometry yields more efficient flow interaction than the straight-foil configuration. These findings indicate that planform optimization is an important design parameter in the development of stern foils to improve the hydrodynamic efficiency of medium-to high-speed commercial vessels.
Enhanced durability and tribological performance of polyvinyl alcohol/layered double hydroxide/tannic acid composites under repeated swelling cycles Dieter Rahmadiawan; Shih-Chen Shi; Wei-Ting Zhuang; Eko Indrawan; Yolli Fernanda; Budi Syahri; Irzal Irzal
Teknomekanik Vol. 7 No. 2 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i2.32872

Abstract

In recent years, the exploration of polyvinyl alcohol (PVA) composites has garnered significant attention due to their versatility applications in aqueous environments. However, despite their promise, neat PVA exhibit limitations such as significant mechanical degradation under repeated swelling cycles. This study investigates the durability and tribological performance of polyvinyl alcohol (PVA) composites reinforced with nickel-iron layered double hydroxide (LDH) and tannic acid (TA) under repeated swelling cycles. Building on previous research that explored composite preparation and initial characterization, this research emphasizes the effects of cyclic swelling on wear resistance, friction behavior, and mechanical properties. Tribological tests were conducted to evaluate the coefficient of friction (COF) and wear rate before and after multiple swelling cycles, alongside tensile strength and strain measurements. The results revealed that the PVA/TA2/LDH2 composite, containing the highest additive content, exhibited the lowest wear rate of 11.52 × 10⁻⁵ mm³/Nm after 3 swelling cycles, demonstrating superior resistance to material degradation. Although PVA/TA2/LDH1 exhibited a slightly lower COF, its wear rate was higher due to reduced reinforcement. Compared to neat PVA, which showed a COF increase from 0.45 to 0.53, the PVA/LDH/TA composites retained their tribological stability, with only a marginal increase in COF and wear rate. Similarly, tensile strength of PVA/TA2/LDH2 decreased by only 11% after 3 cycles (from 33.3 MPa to 30 MPa), while neat PVA experienced a 25.5% reduction (from 30 MPa to 22.5 MPa). These findings highlight the potential of PVA/LDH/TA composites for applications in aqueous environments, offering significantly enhanced long-term performance and reliability.
The impact of project-based learning on 21st century skill development of vocational engineering students: A systematic literature review Alief Depa Rozan; Budi Syahri; Febri Prasetya; Aprilla Fortuna; Agariadne Dwinggo Samala; Soha Rawas
Journal of Engineering Researcher and Lecturer Vol. 3 No. 3 (2024): Regular Issue
Publisher : Researcher and Lecturer Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58712/jerel.v3i3.168

Abstract

This study conducts a systematic literature review to evaluate the impact of Project-based Learning (PjBL) to vocational education and its effects on developing 21st-century skills. Utilizing the PRISMA framework, the study analyzes 21 articles from an initial pool of 1,036 papers from Scopus and Google Scholar databases. The included literature consists of articles published within the last five years (2019-2024) and systematically examines the findings from relevant studies. The analysis results demonstrate that PjBL is crucial in preparing students for a dynamic, technology-driven workforce by enhancing skills such as learning and innovation, information, media, technology, and life and career skills. Despite challenges in implementing PjBL, such as insufficient technological proficiency, inadequate resources, and misaligned curricula, PjBL offers opportunities to develop more effective pedagogical approaches aligned with industry needs. The study emphasizes the importance of collaboration between educators, policymakers, and industry stakeholders to address these challenges and improve vocational education quality. Additionally, the study identifies the need for further research to bridge existing gaps, particularly in developing information, media, and technology skills. Therefore, PjBL is a potential method for equipping students with essential skills for the ever-evolving job market.
Co-Authors Agariadne Dwinggo Samala Alief Depa Rozan Aprilla Fortuna Dieter Rahmadiawan Donny Fernandez Eko Indrawan Febri Prasetya Irzal Irzal Rahmat Azis Nabawi Shih-Chen Shi Soha Rawas Wei-Ting Zhuang Yogi Dian Alfana Yolli Fernanda