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All Journal Jurnal Rekayasa Mesin Jurnal Inovasi Mesin
Nubli, Haris
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Mechanical Engineering

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Optimization Design of NACA 4412 Airfoil Based on Genetic Algorithm for Efficiency and Maximum Lift Force Laksono, Aryo Eko; Bahatmaka, Aldias; Fitriyana, Deni Fajar; Laksono, Galih Tri; Habibullah, Muhammad; Nubli, Haris; Hyung, Cho Joung
Jurnal Rekayasa Mesin Vol. 20 No. 2 (2025): Volume 20, Nomor 2, Agustus 2025
Publisher : Mechanical Engineering Department - Semarang State Polytechnic

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jrm.v20i2.6531

Abstract

The NACA 4412 airfoil, renowned for its exceptional subsonic aerodynamic performance, faces critical operational constraints including elevated drag characteristics and premature stall onset at high angles of attack. While previous investigations have independently examined internal slot modifications and gurney flap implementations for aerodynamic enhancement, the synergistic potential of their combined application to the NACA 4412 configuration remains largely unexplored. This research presents a comprehensive optimization study that strategically integrates internal slot geometry with gurney flap configuration to maximize lift coefficient (CL) and aerodynamic efficiency (CL/CD) through advanced genetic algorithm optimization. The methodology employed high-fidelity computational fluid dynamics simulations using FLUENT with Spalart-Allmaras turbulence modeling, validated against experimental data to ensure accuracy. PCHIP numerical interpolation techniques were utilized to estimate aerodynamic coefficients across comprehensive angle-of-attack ranges not directly simulated. The optimized configuration demonstrated remarkable performance improvements, including a 75.68% increase in lift coefficient, an extension of the critical stall angle from 14° to 16°, enhanced aerodynamic efficiency, and significantly improved flow stability with reduced separation characteristics. These findings establish that the synergistic combination of internal slot and gurney flap modifications can fundamentally transform NACA 4412 aerodynamic performance, particularly excelling in high-angle-of-attack operational scenarios.
The Effect of Variations In Clear Coat Application Distance On The Glitter of The Painting Results Fatkhurokhman, Najib; Hidayat, Hanif; Nubli, Haris
Jurnal Inovasi Mesin Vol. 7 No. 2 (2025): OCTOBER 2025
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jim.v7i2.22624

Abstract

Painting defects in  the repainting  process in the vehicle body repair industry are still a common problem. The main factor causing painting defects is manual application that is not in accordance with standard operating procedures. Painting the vehicle body functions to protect the surface and increase aesthetic value, but there are still frequent painting defects such as rough surfaces, spots, and melting due to improper application. This study aims to examine the distance of application of clear coat to the quality of painting results with minimal defects. The research design used was an experimental  research design with a variety of spraying distances of 10 cm, 15 cm, 20 cm, 25 cm and the measurement of the gloss value was carried out using a gloss meter. The results of the study show that the spraying distance greatly affects the gloss value of the painted results. A distance of 15 cm results in the best gloss value of 90.94 GU with no paint defects, while a distance of 25 cm results in the lowest gloss value of 58.50 GU with rough and dull surfaces. Too close a distance increases the shine power but has the potential to cause defects in the form of  a melted clear coat  layer. This study concluded that the optimal distance for spraying clear coats is 15 cm to achieve high-quality painting results
Co-Authors Aldias Bahatmaka Fatkhurokhman, Najib Fitriyana, Deni Fajar Hidayat, Hanif Hyung, Cho Joung Laksono, Aryo Eko Laksono, Galih Tri Muhammad Habibullah