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All Journal Jurnal Pertanian Agros Jurnal AME (Aplikasi Mekanika dan Energi): Jurnal Ilmiah Teknik Mesin Jurnal Teknik Mesin Indonesia Indonesian Journal of Engineering and Science (IJES) Makara Journal of Technology Prosiding SNTTM
Warjito .
Department Of Mechanical Engineering, Faculty Of Engineering, Universitas Indonesia
Aerospace Engineering Agriculture, Biological Sciences & Forestry Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Electrical & Electronics Engineering Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering

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Modification of Flow Structure Over a Van Model By Suction Flow Control to Reduce Aerodynamics Drag Harinaldi, Harinaldi; Budiarso, Budiarso; Warjito, Warjito; Kosasih, Engkos Achmad; Tarakka, Rustan; Simanungkalit, Sabar Pangihutan; Lay Teryanto, I Gusti Made Fredy
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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

Abstract

Automobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmed's body by changing the orientation of the flow from its original form (modified/reversed Ahmed body). This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. Computational approach used a commercial software with standard kepsilon flow turbulence model, and the objectives was to determine the characteristics of the flow field and aerodynamic drag reduction that occurred in the test model. Experimental approach used load cell in order to validate the aerodynamic drag reduction obtained by computational approach. The results show that the application of a suction in the rear part of the van model give the effect of reducing the wake and the vortex formation. Futhermore, aerodynamic drag reduction close to 13.86% for the computational approach and 16.32% for the experimental have been obtained.
Performance of pico-scale turgo turbine bucket using coconut shells spoons with variations inlet angle and nozzle distance to hydraulic efficiency Muhammad Faridz Athaya; Warjito; Budiarso; Ridho Irwansyah; Muhamad Agil Fadhel; Muhammad Mizan
Jurnal Teknik Mesin Indonesia Vol. 18 No. 1 (2023): Jurnal Teknik Mesin Indonesia
Publisher : Badan Kerja Sama Teknik Mesin Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36289/jtmi.v18i1.429

Abstract

The United Nations Climate Change Conference of the Parties (COP26) has a main agenda, namely evaluating COP21, where the main target of COP21 is to maintain global temperature changes below 2 degrees Celsius (MoEF, 2021). Indonesia itself is committed to zero carbon emissions by 2060, and the target of a renewable energy mix by 2025 is 23%. Indonesia’s own renewable energy potential is 443 GW [13], but not all renewable energy can be used in some areas that have terrain problems. Picohydro turbines are suitable for choice, because these turbines have a relatively constant supply, can be placed in reservoirs and rivers, and are also not dependent on weather. Among several types of picohydro, the Turgo Turbine is a suitable turbine to choose, because it has cheap construction and maintenance costs, and only requires a low head. This study aims to determine the effect of changes in the inlet angle and nozzle distance on the hydraulic efficiency of turgo turbines with coconut shell blades. Variations in the entry angle are carried out, namely 10°, 20°, 30° and distance variations, namely 100 mm, 150 mm, 200 mm. Based on the results of the study, it can be concluded that the greatest hydraulic efficiency is at a variation in the entry angle of 10° with a nozzle distance of 100 mm, that is, numerically by 49%, and experimentally by 41.8%.
THE INFLUENCE OF FROTHER IN FLOTATION USING ELECTROLYSIS FOR BATIK DYEING WASTE SEPARATION Nurrohman, Nurrohman; Warjito, Warjito
AME (Aplikasi Mekanika dan Energi): Jurnal Ilmiah Teknik Mesin Vol. 2 No. 1 (2016)
Publisher : Universitas Ibn Khaldun Bogor

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (518.947 KB) | DOI: 10.32832/ame.v2i1.350

Abstract

Batik waste can increase water characteristics such as turbidity, color and Total Suspended Solid (TSS). A technique for separating Batik from the liquid so that its turbidity, color and TSS decrease is needed. Flotation studies have been conducted using electrolysis to produce the bubbles to separate waste synthetic dye staining result of Batik from the bulk liquid. Research carried out by electrolysis with 316L stainless steel electrodes, inside an acrylic pipe with a height of 100 cm, and 8,4 cm in diameter with a voltage 15 V. Solid aluminum sulfate as a reagent was added to coagulate Batik waste as much as 1 gram per 10 ml of Batik waste. Batik waste was mixed with distilled water beforehand. Frother used was pure ethanol as much as 0.1% v/v. From the research it was discovered that flotation of Batik waste can be used for Batik waste separation with the addition of alum. Alum was proved capable of acting as collector in this type of waste separation. Ethanol as frother used was proved capable of making stable froth and increases the separation efficiency.
FAKTOR-FAKTOR YANG MEMENGARUHI PRODUKSI USAHA TANI BAWANG MERAH DI DESA BARENG KECAMATAN SEKAR KABUPATEN BOJONEGORO Warjito, Warjito; Kustanti, Asihing; Syafrial, Syafrial
Agros Journal of Agriculture Science Vol 26, No 2 (2024): Edisi Juli
Publisher : Fakultas Pertanian, Universitas Janabadra

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37159/jpa.v26i2.4730

Abstract

Mastery of Information and Communication Technology (ICT) has a significant role in developing the agricultural sector, especially in increasing efficiency and productivity. This research aims to investigate the influence of ICT mastery on shallot farming in Bareng Village, Bojonegoro Regency. Through a quantitative approach and collecting primary and secondary data from 93 respondents, multiple regression analysis shows that mastery of ICT makes a positive and significant contribution to agricultural development. Apart from that, factors such as the amount of fertilizer and type of seed also influence production. This study highlights the importance of integrating ICT in agricultural practices to increase efficiency, optimize production and strengthen the competitiveness of agricultural products in the global market. The results of this research provide important insights for policy makers, farmers and other stakeholders in understanding the role of ICT in facing challenges and exploiting opportunities in agricultural development.
PICO-SCALE OPEN FLUME PROPELLER WATER TURBINE PERFORMANCE UNDER VARIATION IN AIRFOIL THICKNESS-TO-CHORD RATIO Christian Romulus Tigor; Warjito Warjito; Budiarso Budiarso; Aji Putro Prakoso
Indonesian Journal of Engineering and Science Vol. 7 No. 2 (2026): Table of Contents: In progress
Publisher : Asosiasi Peneliti Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.51630/ijes.v7i2.223

Abstract

Air pollution from coal-fired power plants contributes approximately 44% of Indonesia’s CO₂ emissions. Transitioning to renewable sources, such as hydroelectric power, offers a viable solution, particularly with open-flume propeller turbines in remote areas. This study investigates the effect of T/C ratios on pico-scale open-flume propeller turbines using NACA 44XX airfoils. Three configurations (0.11, 0.12, and 0.13) with varying rotational speeds were evaluated using computational fluid dynamics (CFD) simulations with mesh motion in ANSYS Fluent, along with analytical methods for torque, power output, and efficiency. T/C 0.13 consistently delivered the best performance, reaching a maximum efficiency of 15.39% at 850 rpm. In contrast, the analytical method found that the maximum efficiency of that configuration is approximately 26% at 1100 RPM. The deviation between the analytical and numerical results arises from the analytical method's limitations in capturing the viscous shear flow around the turbine blades and the gap-clearance loss. The pressure distribution analysis revealed that T/C 0.13 maintained the most balanced high–low pressure zones, minimizing early flow separation. T/C 0.12 exhibited instability at high RPM due to less stable pressure differentials, whereas T/C 0.11 maintained stability with sharper pressure gradients and a higher risk of separation despite lower output. These findings emphasize the role of optimal blade geometry in improving efficiency, pressure–velocity stability, and flow control in small-scale water turbines. However, the lack of experimental testing in this study limits the validity of its results; further experimentation is needed.
Comparative performance of submerged and non-submerged pico-Scale crossflow water turbine Alifarsya Ihsan Maulana; Warjito; Budiarso
Prosiding SNTTM Vol 23 No 1 (2025): SNTTM XXIII October 2025
Publisher : BKS-TM Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.71452/d1gjke23

Abstract

Indonesia’s abundant renewable energy potential. has driven the nation to shift toward clean energy, including small-scale hydropower systems like picohydro. With capacities under 5 kW, picohydro systems are ideal for remote areas due to their simplicity and low operational costs. Crossflow turbines are commonly used for their efficiency under low-head and fluctuating-flow conditions. This study compares turbine performance under three submergence conditions: unsubmerged, partially submerged, and fully submerged. Two methods were employed: analytical calculations (based on velocity triangles to determine speed, torque, and efficiency) and numerical simulations using CFD software ANSYS Fluent. The turbine geometry was modeled in Autodesk Inventor, with a focus on key performance parameters such as torque, power output, and efficiency. Results show that submergence level significantly affects turbine performance. The unsubmerged condition yielded the highest efficiency and power output, as the nozzle flow enters without downstream fluid resistance, allowing optimal energy transfer to the blades. In contrast, partial and full submergence introduced backpressure zones, air pockets, and vortices that increased drag and reduced net torque. Although absolute torque tended to rise due to greater fluid interaction, the RPM decreased, and energy losses increased, resulting in reduced overall power and efficiency.
Co-Authors Alifarsya Ihsan Maulana Asihing Kustanti Budiarso Budiarso Budiarso Budiarso Budiarso Budiarso Budiarso, Budiarso Christian Romulus Tigor Engkos Achmad Kosasih Engkos Kosasih Engkos Kosasih Harinaldi . I Gusti Made Teryanto I Gusti Made Teryanto, I Gusti Made Lay Teryanto, I Gusti Made Fredy Muhamad Agil Fadhel Muhammad Faridz Athaya Muhammad Mizan Nurrohman Nurrohman Prakoso, Aji Putro Ridho Irwansyah Rustan Tarakka Rustan Tarakka Sabar Pangihutan Simanungkalit Sabar Simanungkalit Sabar Simanungkalit, Sabar Syafrial Syafrial