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Jurnal Vokasi Mekanika
Published by Universitas Negeri Padang
ISSN : 26561697     EISSN : 26562812     DOI : https://doi.org/10.24036/vomek.v4i3
Core Subject : Education, Engineering,
Education Mechanical Engineering
Jurnal Vokasi Mekanika menyambut baik kiriman yang memberikan wawasan tentang isu-isu terkini dan utama yang berkaitan dengan pendidikan kejuruan dan teknologi serta ilmu Keteknikan dalam bidang Teknik Mesin. Jurnal ini menyediakan tempat bagi para peneliti dan praktisi untuk mendiskusikan, mengejar, dan mempromosikan pengetahuan di bidang studi pendidikan teknologi kejuruan dan ilmu Keteknikan dalam bidang Teknik Mesin yang sedang berkembang pada saat sekarang ini. Bahasa naskah ditulis dalam bahasa Indonesia. Harus ada diskusi kritis tentang isu-isu baru dan signifikan dan kontribusi ke bidang terkait. Artikel dapat berasal dari salah satu bidang berikut: Teori, Strategi, Pendekatan, Metode Atau Model Pembelajaran TVET Penerapan dan Pengembangan Media, Modul, Bahan Ajar dan Buku Ajar Manajemen dan Kebijakan TVET Pengembangan Kurikulum TVET Evaluasi Program dan Pembelajaran TVET Penerapan Teknologi Kejuruan Terkait TVET Pengembangan Profesionalitas Guru TVET Energi dan energi terbarukan Sistem produksi dan Manufaktur Rekayasa bahan Teori dan aplikasi dinamika fluida komputasi Ilmu ilmu Teknik Mesin Lainnya.
Arjuna Subject : Teknik (semua kategori) - Teknik Mesin
Articles 427 Documents
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Calculation of High Pressure Heater Efficiency in the Feedwater System of PT PLN IP Teluk Sirih Unit 2 Steam Power Plant Andre Kurniawan; Arwizet K; Yolli Fernanda; Zulvani Adha
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 1 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/v1frxb70

Abstract

PT PLN IP Teluk Sirih is a coal-fired steam power plant that supplies electricity to the West Sumatra region. In steam power plants, the High Pressure Heater (HPH) functions as a heat exchanger that preheats feedwater before entering the boiler by utilizing extraction steam from  turbine. Damage or performance degradation of the HPH can reduce its effectiveness and lifespan, decrease feedwater temperature, increase the required heating in  boiler, raise fuel consumption, and ultimately lower the overall efficiency of the power plant cycle. Therefore, this study aims to determine the efficiency of HPH at PT PLN IP Teluk Sirih Unit 2 in order to support proper maintenance planning and reduce operational costs. The research employs a quantitative method with a descriptive–analytical approach using actual operational data obtained from the Distributed Control System (DCS) of PLTU Teluk Sirih Unit 2. The efficiency of HPH is calculated by comparing the heat released by the steam  and the heat absorbed by the feedwater  or HPH 1 and HPH 2. The variables used include the feedwater inlet temperatures of 192.9 °C for HPH 1 and 141.5 °C for HPH 2. The results show that the efficiency of HPH 1 is 91.26%, while the efficiency of HPH 2 is 88.11%. For HPH 1,  and  are 49,552,500 kJ/h and 54,297,300 kJ/h, respectively, whereas for HPH 2,  and  are 71,613,300 kJ/h and 81,288,480 kJ/h. These results indicate that a higher inlet temperature leads to a greater ratio between  and  , and consequently to a higher HPH efficiency.  
Numerical Simulation of the Effect of Blade Shape on Vertical Axis Wind Turbine Using NACA 0015, NACA 4415, and NACA 7510 Randi Purnama Putra; Yolli Fernanda; Fitrah Qalbina; Alhakim, Rezki
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 1 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/8fw5gp43

Abstract

Energy is a resource that can be used to perform various tasks, including fuel, electricity, mechanical energy, and heat. With technological advances and global economic development, the demand for electricity will continue to increase. This drives various research efforts towards alternative energy sources, ranging from the development of existing tools to the creation of new innovations. Wind turbines work by utilizing the kinetic energy of the wind flow to rotate the blades, which are then converted into electrical energy through a generator system. The purpose of this study is to analyze the effect of curvature shape on the Lift Coefficient (Cl), Drag Coefficient (Cd), and Power Coefficient (Cp) of vertical axis wind turbine blades. Simulations were carried out in 3D using ANSYS Fluent software and the SST turbulence model, with wind speeds ranging from 4 to 7 m/s. The aerodynamic profiles analyzed were NACA 0015, NACA 4415, and NACA 7510. Aerodynamic simulations of vertical axis wind turbines were carried out using a steady-state approach with a multi-reference frame (MRF) rotation model to obtain the average aerodynamic characteristics of the rotor. The simulation results show that NACA 4415 produces the best Cl value with relatively controlled Cd, while NACA 0015 shows the worst aerodynamic performance. NACA 7510 produces the highest Cp value at all wind speed variations, despite low Cl and high Cd values, indicating that the drag mechanism dominates torque generation at low speeds.
Analysis of the Effect of Feed Rate, Spindle Speed and Coolant on Surface the Roughness of ST 37 Steel in the Turning Process Rahmatul Fauzan Mulyadi; Syahril; Rifelino; Zainal Abadi
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 2 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/epr1f741

Abstract

Surface roughness is an important parameter in turning processes, as it directly affects the performance and service life of mechanical components. This study aims to examine the influence of feed rate, spindle speed, and coolant application on the estimated surface roughness (Raest) of ST 37 steel under conventional turning conditions. A 2³ full factorial experimental design was employed, involving eight treatment combinations consisting of two feed rate levels (0.040 and 0.100 mm/rev), two spindle speed levels (315 and 400 rpm), and two cooling conditions (with and without coolant). Surface roughness estimation was carried out using digital image analysis with ImageJ software based on optical microscope images. The analysis utilized gray-level intensity distributions, which were then converted into roughness values using an empirical scaling approach. The results indicate that increasing the feed rate led to a rise in Raest ranging from 1.74% to 7.11%, while higher spindle speeds contributed to an increase in surface roughness between 4.54% and 11.91%. In contrast, the use of coolant reduced surface roughness by an average of 9.20%, mainly due to its role in minimizing heat and friction during machining. The optimal parameter combination was obtained at a spindle speed of 315 rpm and a feed rate of 0.040 mm/rev with coolant, producing an Raest value of 1.495 µm, which falls within ISO roughness class N7. Overall, all specimens were classified within ISO N7, indicating a semi-finishing surface quality.
Effect of Rice Husk Ash and Clay Powder as Cooling Media in Post Weld Heat Treatment (PWHT) on The Impact Toughness of SMAW-Welded SS400 Steel Angga Hermawansyah; Zainal Abadi; Delima Yanti Sari; Rifelino
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 2 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/f6gkaq38

Abstract

This study investigates the effect of variations in cooling media during Post Weld Heat Treatment (PWHT) on the impact toughness of low carbon steel SS400. The main problem addressed in this research is how differences in cooling medium characteristics influence the cooling rate, which subsequently affects the impact toughness of welded material. The objective of this study is to determine the effect of using rice husk ash, clay, and air as cooling media on the impact toughness value of SS400 steel. The experimental method was employed by applying PWHT to SMAW-welded specimens, followed by Charpy impact testing to obtain the final deflection angle, which was then converted into impact energy and impact value (HI). The results show that clay cooling medium provides the highest average impact toughness value of 1.175 J/mm², followed by rice husk ash at 1.107 J/mm², while air cooling yields the lowest value of 0.845 J/mm². These differences indicate that the thermal characteristics of the cooling media significantly influence the material’s ability to absorb energy before fracture, which is related to the stability of the cooling rate during the PWHT process. It can be concluded that variations in cooling media affect the impact toughness of SS400 steel, where more stable cooling conditions lead to higher toughness values.
Analysis Of The Effect Of Penstock Diameter Variation And Nozzle Flow Velocity On Pelton Turbine Performance Using Computational Fluid Dynamics (CFD) Revaldo Nur Hidayat; Randi Purnama Putra; Yolli Fernanda; Fitrah Qalbina
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 2 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/18k9e415

Abstract

The performance of a Pelton turbine in micro-hydropower plants is influenced by penstock design and fluid flow conditions. Variations in penstock diameter can lead to changes in head loss, flow velocity, and energy transfer efficiency. This study aims to analyze the effect of penstock diameter variation and nozzle flow velocity on Pelton turbine performance under different head conditions using the Computational Fluid Dynamics (CFD) method.Simulations were conducted using penstock diameters of 4 inches, 5 inches, and 6 inches with ANSYS software. The results show that the respective head losses are 0.010 m, 0.006 m, and 0.0028 m, indicating that larger diameters reduce friction losses in the flow. The corresponding nozzle velocities are 8.90 m/s, 9.08 m/s, and 8.64 m/s, with the highest value observed at the 5-inch diameter due to the balance between flow rate and energy losses. The resulting torque values are 2.13 Nm, 2.55 Nm, and 2.60 Nm, while the rotor rotational speeds are 150.87 W, 189.07 W, and 194.90 W. The effective power generated is 65.59 W, 80.21 W, and 77.79 W, with efficiencies of 43.77%, 42.44%, and 39.95%, respectively. The results indicate that a 5-inch penstock diameter provides the most optimal performance, as it achieves the best balance between head loss, flow distribution, and fluid energy transfer.
The Analysis of Diameter Expansion and Connection Angle Variations Effects In Hyropower Penstock Pipe Bend on Pressure Drop Using Computational Fluid Dynamics Simulation Agung Widodo; Dony Hidayat Al-Janan; Aldias Bahatmaka
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 2 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/wb52b413

Abstract

Pembangkit Listrik Tenaga Air (PLTA) memanfaatkan pipa pesat (penstock) sebagai saluran utama pengaliran air dari reservoir menuju rumah pembangkit. Belokan pada jalur pipa pesat berpotensi menyebabkan pressure drop yang dapat menurunkan efisiensi sistem secara keseluruhan. Penelitian ini bertujuan untuk menganalisis pengaruh variasi perbesaran diameter dan variasi sudut penghubung pada belokan pipa terhadap nilai pressure drop. Kajian teoritis  yang digunakan meliputi prinsip persamaan kontinuitas dan persamaan bernoulli dalam sistem perpipaan. Penelitian ini menggunakan pendekatan kuantitatif dengan metode eksperimen berbasis simulasi Computational Fluid Dynamics (CFD) menggunakan perangkat lunak ANSYS Fluent 2019 R3. Pengambilan data dilakukan menggunakan simulasi numerik numerik terhadap 13 variasi desain belokan pipa yang mencakup variasi perbesaran diameter 1D, 1,25D dan 1,5D dengan variasi sudut penghubung 10°, 20°, 30°, 45°, 60° dan 90°, menggunakan model turbulensi k-epsilon realizable dengan kecepatan inlet 7 m/s. Hasil simulasi menunjukkan bahwa nilai pressure drop dipengaruhi secara signifikan oleh kedua variabel. Semakin kecil sudut penghubung, semakin rendah nilai pressure drop yang dihasilkan, dengan peningkatan sudut dari 10° ke 90° menyebabkan kenaikan pressure drop sebesar 898,0% pada variasi 1,25D dan 1.707,9% pada variasi 1,5D. Perbesaran diameter efektif menurunkan pressure drop hanya pada sudut penghubung kecil, sedangkan pada sudut besar justru memicu separasi aliran dan zona resirkulasi. Desain paling optimal adalah 1,25D dengan sudut penghubung 10°, yang menghasilkan pressure drop sebesar 1.094,350 Pa atau lebih rendah 47,7% dibandingkan desain standar 1D. Penelitian ini memberikan rekomendasi desain belokan pipa pesat yang mampu meminimalkan kerugian tekanan guna meningkatkan efisiensi sistem PLTA. 
Data-Driven Analysis of Machining Parameters Affecting Surface Roughness (Ra) in CNC Turning of Al6061 Using OLS Method Dimas Ardiansyah Halim; Arbey, S; Rio Evandi; Tosa Susilo; Joko Suparno
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 2 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/e9fjmj14

Abstract

This study aims to analyze the effect of machining parameters on surface roughness (Ra) in the CNC turning process of Aluminum 6061 using the Ordinary Least Squares (OLS) approach. The investigated parameters include cutting speed (v), feed rate (f), nose radius (r), and spindle speed (n). The experimental design was developed using a Central Composite Design (CCD) with five coded levels (+2, +1, 0, ?1, ?2). The machining process was carried out on a CNC GSK 980TDi lathe using CCMT inserts with nose radii of 0.2 mm, 0.4 mm, and 0.8 mm, while the surface roughness was measured using a Mahr Marsurf M300 tester with an accuracy of 0.076 µm. Experimental data were analyzed using the OLS method to determine the most dominant parameters affecting Ra. The results show a coefficient of determination (R²) of 0.932 and an adjusted R² of 0.868, indicating that the regression model provides an excellent level of fit. The nose radius (r) and spindle speed (n) were found to be the most significant factors influencing surface roughness, exhibiting opposite effects. This data-driven approach demonstrates the effectiveness of the OLS method in identifying critical machining parameters in CNC turning processes.

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