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Mekanika: Majalah Ilmiah Mekanika
Published by Universitas Sebelas Maret
ISSN : 14127962     EISSN : 25793144     DOI : https://doi.org/10.20961/mekanika
Core Subject :
"Mekanika: Majalah Ilmiah Mekanika" is an open-access journal published by Mechanical Engineering Study Program, Faculty of Engineering, Universitas Sebelas Maret. Mekanika invites scholars, researchers and practioners who have interest in mechanical engineering to publish their articles and also provides forums for them to share their works and knowledge. Mekanika focuses on the area of materials engineering and science, design, energy, manufacturing and construction but is not limited to. Both English and Bahasa are accepted in this journal. Mekanika has two issues every year (March and September) and aims to publish more frequently in the future.
Arjuna Subject : Teknik (semua kategori) - Teknik Mesin
Articles 91 Documents
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Pressure Drop and Void Fraction of Two-Phase Flow (Air-Water) in Grooved Vertical Pipes Supa Kusuma Aji; Nicky Suwandhy A. S; Chandra Gunawan; Bayu Pranoto; Hangga Wicaksono
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.76968

Abstract

Two-phase flows consisting of liquids and gases are often found in everyday life and are used on an industrial scale. In an industrial environment, this flow has many weaknesses, including pressure drop and void fraction. One strategy to reduce losses that arise is to use passive methods. The passive method used is to utilize the shape of the grooves in the channel. In this study, the flow is used to determine its effect on the pressure drop and void fraction that appears in two-phase flow. The experimental method was used for this study. The test pipe is equipped with 16 grooves, while the smooth pipe (without grooves) is used as a comparison. The test pipe is made of acrylic material. The water fluid is circulated using a centrifugal water pump with a superficial speed of 0.33-0.42 m/s. Air fluid is supplied using a compressor with superficial speeds of 0.049, 0.066, and 0.082 m/s. Measurement of pressure drop was carried out using a pressure transmitter with an Arduino data logger. The void fraction is calculated by determining the ratio of the volume fraction of water and air in the test tube. The results of the study revealed that the use of 16 grooves in the pipe can reduce the pressure drop and cavity fraction that appears when compared to smooth pipes.
Corrosion Rate Analysis and Prediction of the Remaining Life of the Research Vessel to Improve Ship Safety Aspects Andi Cahyo Prasetyo Tri Nugroho; Cahyo Sasmito; Abid Paripurna Fuadi; Dany Hendrik; Cakra Wijaya Kusuma Rahadi; Rizqi Dian Permana; Noor Muhammad Ridha Fuadi
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.75062

Abstract

Corrosion is a major concern in the marine industry, compromising the safety and integrity of ships. This paper presents a corrosion rate analysis and prediction of the remaining life of the Baruna Jaya IV research vessel using non-destructive testing (NDT) ultrasonic testing to improve ship safety aspects. The NDT ultrasonic testing was conducted on the ship's hull to evaluate the thickness and detect any hidden corrosion. The results were used to develop a corrosion rate model and predict the remaining life of the ship using a probabilistic model. The study found that the corrosion rate of the ship was high, and the remaining life of the ship was estimated to be less than five years. The study’s findings can be used to develop a maintenance and repair strategy to reduce corrosion and improve the safety of the Baruna Jaya IV research vessel.
Predicting the Drag Coefficient Characteristics of Ocean Bottom Unit (OBU) Float Array Model for Early Warning Tsunami Systems Using Computational Fluid Dynamics (CFD) Method Yudiawan Fajar Kusuma; Ilham Hariz; Hanni Defianti; Buddin Al Hakim; Arfis Maydino F. Putra
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.75079

Abstract

As a country along the Pacific Ring of Fire, Indonesia faces various natural disaster threats, including tsunamis. Therefore, an early tsunami warning system is crucial for detecting potential tsunami waves. The early tsunami warning system encompasses several complex components, one of which is the Ocean Bottom Unit (OBU) floater. This paper discusses the performance of various types of floater arrays for tsunami early warning systems using Computational Fluid Dynamics (CFD) simulations. The study focuses on coefficients, especially the drag coefficient, and the influence of the number of float arrangements on the flow pattern around the buoy or Ocean Bottom Unit (OBU) array. Among the five numerical simulation models, the six-couple floater has the highest drag and lowest lift coefficients, while the single floater has the lowest drag coefficient. The percentage of difference in drag coefficient between single floater and couple series floater is quite significant, reaching up to 50%. The moment coefficient is also affected by the number of floaters, with a series of five couple floaters having the highest moment coefficient at a Reynolds (RE) number of 2 × 106. The advantage of using the CFD method is that it can visualize current velocity, which is crucial for understanding the flow pattern around the float system. The results indicate that the flow pattern becomes more complex as the number of floater arrays increases, which leads to more vortices between the floater, resulting in increased turbulence and drag coefficient.
Water Pump Control System using Pulse Width Modulation Method Based on Arduino Uno R3 Usman, Dani; Permana, Dimas Surya
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.89449

Abstract

The availability of sufficient energy must support the rapid development of technology. The availability of electrical energy is decreasing. The saving of energy is one of the ways to solve this problem. One of the uses of electricity in clean water pumps, where clean water is the basic necessity of human life, therefore control system and auxiliary equipment is needed that is able to supply water according to the capacity of the need. However, often the use of the pump is not proportional to the capacity of the needs and the pump is often operated continuously, so that electricity and water are wasted. In this research, the use of water pumps is controlled, the rotation of the pump drive motor can be adjusted so that the pump output is in accordance with the water consumption load. The speed of a Direct Current (DC) motor is determined by the voltage. The higher the voltage, the faster the rotation. The focus of this research is to optimize the power efficiency of DC water pumps by using the Pulse Width Modulation (PWM) method to control the speed of the pump.
Analyze The Effect of The Impeller Type on Bearing Rating Life Tsani, Fatchan Mubarok; Pramesti, Yasinta Sindy
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.86101

Abstract

One of the essential components of a balancing machine is the bearing, which is a crucial component that ensures stability, precision, and efficiency in the balancing process. Although there were high-quality bearings on the market, ongoing research was needed to ensure that balancing machine bearings could supply the specific needs of the industry and continued to improve their reliability and efficiency; the use of bearings specifically designed for balancing applications and of high-quality is necessary to ensure optimal performance and accurate results. This study aims to examine the impact of varying impeller types on balancing machine-bearing life in commercial companies. This research adopts a quantitative causality method, collecting data and samples during the study and then analyzing them using the Analysis of Variance (ANOVA) method. Bearing life is measured using a sum by combining several factors. The results of the research revealed that from ANOVA analysis with an error percentage of 0.05, a significance value of 0.006 was obtained and F = 44.582, Ftable = 9.55, which means calculated F > Ftable so it can be concluded that the type of impeller was affected bearing life.
An MR Damper Parametric Model with luz(...) Projection Function and Its Application in an Open-loop Force Tracking Control System Hidajat, Raymundus Lullus Lambang Govinda; Imaduddin, Fitrian; Santoso, Budi; Irianto, Irianto; Putra, Azma; Ubaidillah, Ubaidillah
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.90437

Abstract

This research discusses a parametric model with a luz(...) projection function for an outer bypass Magnetorheological (MR) damper with a meandering type valve and its application in an open-loop force tracking control system. This parametric model with the luz(…) projection function has been developed previously. The MR damper force can be controlled with open-loop force as a standard control strategy. Research on the performance of the MR damper model in open-loop control systems usually uses non-parametric models. Thus, the novelty of this research is that it uses a parametric model, i.e., the model of the luz(...) projection function as the model of the outer bypass MR damper with a meandering type valve. The proposed open-loop control system uses an inverse model that produces an electric current according to the desired force. The force tracking control scheme was realized with computer simulations using a state space approach. These simulation results show that the model with the luz(…) projection function can efficiently and accurately track the desired force in an open-loop force-tracking control system. The desired force is sinusoidal, square, and sawtooth waveform. Relative Error (RE) of 0.000, 0.0123, and 0.0563, respectively, are achieved. 
Recent Advancements in Ocean Current Turbine Blade Design: A Review of Geometrical Shape, Performance and Potential Development using CAE Fajri, Aprianur; Jurkovič, Martin; Kandimba, Enock Michael; Lutanto, Agus; Falah, Fajrul; Adiputra, Ristiyanto; Firdaus, Nurman
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.87374

Abstract

The global energy demand is experiencing a significant surge, reaching 442 exajoules in 2023. The urgency to develop renewable energy sources intensifies as global energy needs continue to escalate, coupled with the detrimental impact of fossil fuel consumption on climate change. Ocean current energy has emerged as a promising renewable energy source due to its predictability and minimal environmental impact. However, the efficiency and reliability of Ocean Current Turbines (OCTs) depend highly on their blades' design and performance. This review provides a comprehensive overview of recent advancements in ocean current and tidal current turbine blade design and the challenges and issues associated with their operation and maintenance. The paper discusses various design aspects, including blade geometry, material selection, hydrodynamic performance optimization, and bio-inspired designs. Additionally, it highlights the common failures and degradation mechanisms of turbine blades, such as fatigue, erosion, and cavitation. Furthermore, the review explores the challenges faced in developing and deploying OCTs, such as improved blade durability, cost-effectiveness, and environmental compatibility.
Design of Airscrew Propeller as an Alternative Main Propulsion for Wing in Surface Effect (WiSE) A2C Using the Simplified Method Approach Sasmito, Cahyo; Pujiwat, Rutma; Priatno, Dany Hendrik; Iskendar, Iskendar; Khoirudin, Muh Hisyam; Eskayudha, Dimas Bahtera
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.77937

Abstract

This study focused on developing an airscrew propeller as an alternative propulsion system for the Wing in Surface Effect (WiSE) A2C, employing a rigorous and systematic scientific approach. The design and calculation methodology were grounded in the "simplified method" introduced by Hovey. This technique has proven effective for preliminary propeller design despite its reliance on several assumptions and simplifications. This method balances practicality with empirical data, offering a straightforward framework for generating initial design parameters without extensive computational demands. Although the simplified method has limitations, such as its dependence on empirical observations and reduced computational precision, it remains effective for developing foundational design concepts. The study leveraged this approach to create a propeller design that aligns with the aerodynamic and performance requirements specific to the WiSE A2C. The resulting design features an airscrew propeller with an RAF-6 airfoil profile and a diameter of 685 mm. The RAF-6 profile was chosen for its favorable aerodynamic characteristics, including a high lift-to-drag ratio, which is crucial for optimizing propulsion efficiency. This tailored design ensures compatibility with the operational environment of the WiSE A2C, enhancing its overall performance and stability while meeting specific aerodynamic goals.
Enhancing Ship Stability: A Comparative Analysis of Single and Double Chine Hull Configurations of Semi-Planning Hull at High Speed Ghyferi, Andi Abdullah; Bahatmaka, Aldias; Naryanto, Rizqi Fitri; Won, Lee Sang; Cho, Joung Hyung
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.90734

Abstract

Ship stability could be considered one of the defining aspects of marine transport, as it directly influences the safety and performance of the ship. Past works have found hull geometry critical in the stability issue; however, the impact of various Chinese configurations under different operation scenarios is missing. This paper seeks to address this gap by studying the effects of Chinese single and double geometries on stability, primarily concerning trimming by stern angles in compliance with the High-Speed Craft (HSC) 2000. Annex 8: Monohull Intact Stability Criteria. Stability calculations using Maxsurf software were done concerning angles of the steady heel, the area under the righting levers (GZ) curve, maximum GZ, and initial transverse metacentric height (GMt). The study showed that both Chinese configurations conformed to the prescribed stability standards. Still, the double Chinese configuration showed better results in terms of stability at a 2-degree heel angle, with a GZ value of 1.692 and the highest GMt value in a steady state. Therefore, the research establishes enhanced stability benefits that the users stand to benefit from by adopting double chine configurations relative to single chine styles.
Hydrodynamic Performance Assessment of Straight and Helical Hydrokinetic Turbine Hydrofoil-Blade Sections in River Oyun, North-Central Nigeria Ladokun, Laniyi Laniran
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.92527

Abstract

The performance of lift-based hydrokinetic rotor turbines usually depends on the blade sections or hydrofoil profile. Different hydrofoil blade sections, having different profiles and geometries, give different coefficients of performance in different hydrodynamic settings. This study examined the influence of blade geometry on the power stage characterization of vertical axis crossflow hydrokinetic turbines under conditions of low river current velocity. Two turbines have been selected to characterize the power stage. Pre-developed straight-bladed National Advisory Committee for Aeronautics (NACA) 0021 hydrofoil blade sections and a Gorlov helical/curved NACA 0021 pattern were used in the hydrodynamic experimental characterization along River Oyun, Kwara State, North-Central Nigeria. The graphical ratio of the coefficient of performance, CP,which measures the efficiency of the turbine blade sections converting kinetic energy into mechanical energy, and the turbine blade Tip Speed Ratio (TSR), was used to analyze the hydrodynamic blade performance characterization. The peak CP values, the optimal TSR, the CP curve shape, and the stall regions from the CP-TSR chart were used to determine the hydrofoil with optimal performance.

Page 9 of 10 | Total Record : 91

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