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Mesin
Published by Institut Teknologi Bandung
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Core Subject : Engineering,
Mechanical Engineering
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Articles 539 Documents
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COMPUTATIONAL AERODYNAMIC STUDY OF A HATCHBACK CAR MODEL Rio Teguh Kurniawan; Lavi R Zuhal; Ema Amalia
Mesin Vol. 23 No. 1 (2008)
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Abstract

"Ahmed Body" is a well-established model of a hatchback car. In this study, computational simulations were conducted by using existing CFD software to capture "drag crisis" phenomena. Flow is assumed as incompressible flow with Reynolds Number of 4.3 x 10^6. A half of "Ahmed Body" was used in computational simulations with RANS method. Turbulence models that were employed mostly are k-e. The amount of grid cells used in computation is about 300.000. Computations were carried out mostly to get drag coefficients and also to examine vortex structure related to it. In "drag crisis" phenomena, maximum drag coefficient is reached at rear window angle of 30 degrees. Placement of spoilers and vortex generator has succesfully reduced the maximum drag coefficient at the critical angle of 30 degrees.
ANALISIS KESALAHAN FUNGSI RESPON FREKUENSI AKIBAT KETERBATASAN WAKTU REKAM PADA PENGUJIAN GETARAN DENGAN EKSITASI IMPAK KASUS DOMAIN WAKTU KONTINU Noval Lilansa; Zainal Abidin; Djoko Suharto
Mesin Vol. 23 No. 1 (2008)
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Abstract

This paper derives mathematical equation describing the relation between errors in FRF due to limited record time length, record time and the time constant of a vibration system modelled by the I- dof vibration system with viscious damping. It is assumed in derivation of the equations that both impact excitation as well as response signals are not contaminated by noises. Moreover, the impact excitation is assumed to be a delta Dirac function. Consequently, the spectrum of the excitation is constant for all frequencies. The derived mathematical equations results show that the FRF error is a complex function so that is can be expressed by the magnitude anf phase functions. The magnitude of FRF error represent the maximum possible error occuring in the FRF magnitude. The maximum possible error occuring in the FRF magnitude at fn is influenced by parameters, such as record time and time constant of the structures. This maximum possible error shows an exponentially decreasing nature as the ratio of these parameters increases. Based on the derived equation, a recording of the response signal within three times of the system time constant results in the maximum possible error at fn in the FRF magnitude in the order of 5% of the theoritical FRF magnitude. Such recording can be performed if the peak amplitude of the response signal ceases to about 5% of the initial peak amplitude at the end of the record time for between 0.001 and 0,1.
STUDI NUMERIK KARAKTERISTIK ALIRAN SILANG PADA SILINDER BUNDAR TUNGGAL Berkah Fajar
Mesin Vol. 23 No. 1 (2008)
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Abstract

This study deals with numerical investigation of hydrodynamic properties of fluids flow accross a single circular cylinder. The flow is assumed incompressible, laminar with Reynolds number 0,0001, 2, 20, 40, 100, 200, 400, 1000, 4000 and 20000. The work started with generating geometrical mesh, and then continue with the numerical simulation. The simulations were done by varying the pressure with standardm linier or second order interpolation, momentum discretisation (first-order upwind, second-order upwind, Power law), and pressure velocity coupling (SIMPLE, SIMPLEC, and PISO). The simulation results agree with the experimental results done by other. The comparison parameter used were flow pattern, Strouhal number, drag coefficient, and separation position. The simulation results also show that the flow characteristic with Reynolds Number larger than 40 is depend on time (unsteady). This is caused by vortex shedding at the rear of the cylinder. The body force (lift and drag) on the cylinder change periodically and the value agree with the experimental results.
STUDI BLOCKAGE EFFECT TERHADAP ALIRAN PADA KONFIGURASI WING-BODY FAIRING Khoiri Rozi; Herman Sasongko
Mesin Vol. 23 No. 2 (2008)
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Abstract

The study was performed to acquire information on the qualitative flow condition and dynamical blockage effect on wing-body fairing configuration. The study was used to computational fluid dynamics to provide the pathlines patters and the total static pressure distribution in the vicinity junction region. Results of study in the research indicated that flow pattern influences by variation of angle of attack. As increasing of angle of attct so that the saddle point position move in to pressure side and away from wing surface. Meanwhile, separation line or imprint horseshoe vortex due to increasing angle of attack became more than opened. Results of total static pressure distribution show that the blockafe effect area seems deeply on incoming trailing edge location. Therefore, as increasing of angle of attack will be blockage effect to fluid flow on pressure side and suction side stronger.
PENGEMBANGAN PERSAMAAN KORELASI PENDIDHAN KOLAM UNTUK REFRIGERAN HIDROKARBON Ari Darmawan Pasek; Willy Adriansyah; Hery Hery; Hengky Leo
Mesin Vol. 23 No. 2 (2008)
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Abstract

Hydrocarbons (HC) are considered as the alterative substitutes of CFC and HCFC refrigerants. Using it as new refrigerants needs a complete knowledge of its characteristics. One of them is the boiling heat transfer coefficient. Series of experiments were carried out to investigate this characteristics. Experiments had been carried out with R-12 (CFC) and R-22 (HCFC) and their substitutes, HC-12 and HC-22. Tested refrigerant was conditiond at a saturated state and an electric heater immersed in the refrigerant pool of liquid was used as the boiling surface. Boiling heat transfer coefficient is determined as the ratio between the heat flux and the excess temperature on the boiling surface. The experimental results were compared between R-12 and R-22 with their substitutes. The experimental results were compared with the correlation equations proposed by researchers. Based on the analysis results, modified correlation equations are proposed for the tested refrigerants.
ANALISIS TERMODINAMIKA SIKLUS HIBRID UNTUK PEMBANGKIT LISTRIK TENAGA PANAS BUMI I Made Astina; Kadek Edy Kurniawan; Merly Pastalozi
Mesin Vol. 23 No. 2 (2008)
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Abstract

Modification of the conventional cycle in a geothermaL power plant is an alternative way that can be conducted in efficient conversion of thermal energy to be electric energy. Combination of Brayton cycle with fossil fuel energy sources and Rankine cycle utilizing geothermal energy is interest of this study. Kamojang Geothermal power plant is chosen as an object of casestudy. A software was developed to accurately evaluate the thermodynamic cycle with any modification. The software is supported by thermodynamic properties database directly derived from equations of state. Hybrid cycle analysis was conducted by comparing the conventional geothermal system operating with independent Rankine cycle such as the current Kamojang geothermal power plant in accordance with rational data ernd assumptions.Simulation results show that 157.88% of power increment, 58.17% of efficiency increment for using organic working fluid R-134a. Replacing R-134a with organic working R-600 afford 162.89% of power increnrent and 63.76% of efficiency increment. Ratio of the net power increment respect to the heating input of fuel is 0.52. This high enhancement is achieved for gas turbine inlet temperature of 1100 celcius degree, pressure ratio of 20, gas temperatltre front steam heater at 350 celcius degree, steam temperature from the heater at 250 celcius degree, and organic turbine inlet pressure and temperature at 35 bars and 340 celcius degree, respectively.
RANCANG BANGUN MICRO AIR VEHICLE KONFIGURASI TAILLESS Taufiq Mulyanto; Arinta H Wijaya; Hari Muhammad
Mesin Vol. 23 No. 2 (2008)
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Abstract

Nowadays, Micro Air Vehicle (MAV) is mostly developed for surveillance purpose, either for military or civilian. In this article, a design and building of a MAV will be presented. A tailless configuration was chosen. The design and build process started with a study of several design parameters of existing MAVs. Then, it is followed by initial sizing, detail design and production of the MAV. In general, the designed MAV could meet the design requirements and objectives stated. Some preliminary tests had shown that the basic flying characteristics was sufficiently good, although further development still has to be done. The design and build process was also able to evaluate the implementation of some aircraft design formula and method being implemented to design MAV.
CORE SUB-COOLED BOILING OF THE BANDUNG TRIGA 2000 REACTOR K Kamajaya; Henky P.R; E Umar; P. Ilham Yazid
Mesin Vol. 23 No. 2 (2008)
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Abstract

In 2000, the TRIGA 2000 reactor in Bandung completed a commissioning program and received an operating license at 2000 kW. The Indonesia regulatory body (BAPETEN) issued a 15-year license, to operate the reactor at 2000 kW. During the commissioning tests, bubbling at the reactor core was observed and considered acceptable by General Atomic experts. The sub-cooled boiling observed during the commissiong tests confirmed the predictions of the thermal hydraulics calculations performed by General Atomics and presented in the safety analysis report. In 2004 the operating staff of the Bandung TRIGA 2000 Reactor observed an increase in the amount and size of the bubbles emanating from the core and in January 2005 the BAPETEN after an inspection and discussion with the operating irganization decided to limit the reactor power to 1250 kW. In January 2005, IAEA team mission organize a favt-finding mission to have a better understanding of the safety implications of the reactor bubbling and to propose an action plan to address and solve the issue. Followint this obligation, BATAN submitted to the Agency the current verison of the SAR at the end of 2007. In March 2007, IAEA team mission came to Indonesia di review the SAR was combined with the follow-up on the recommendation from previous mission on investigation of core bubbling phenomena,
Evaluation on the Temperature and Calcination Time During Sol-gel Coating of TiO2 on Iron Foam substrate Raden Dadan Ramdan; Luqman Haris; Hendra Hermawan; Bambang Sunendar
Mesin Vol. 26 No. 1 (2017)
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Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/MESIN.2017.26.1.1

Abstract

Iron foam is iron based material which is widely applied due to its unique properties. However since corrosion is also a problem for this material, coating with innert material is required in enhancing its applications. In the present research, TiO2 coating is performed on iron foam suface by sol-gel dipping method. Focus is given on the study of the effect of calcinations temperature and time on the coating characteristics. TiCl4 is used as the precursor with concentration of 0.3 M, added with 1M HCl solution and chitosan soluation with concentration of 1%. Calcination is performed at temperature of 400, 500 dan 600oC and calcinations time of 1 and 3 hours inside controlled gas furnace using nitrogen atmosphere. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) characterization data shows that TiO2 particles form on the iron foam substrate. SEM characterization on the sample heated at 400oC and heating time of 1 hour shows the formation of nano particle titania (0.06 μm) which is homogeneously distributed with less agglomeration than others and considered as the best sample in the present research. As the temperature and time of calcinations increase, more inhomogeneous particle distribution and bigger particles form.
Sifat Tarik Dan Sifat Impak Komposit Polipropilena High Impact Berpenguat Serat Rami Acak Yang Dibuat Dengan Metode Injection Molding Mardiyati Mardiyati; Nurdesri Srahputri; Steven Steven; Rochim Suratman
Mesin Vol. 26 No. 1 (2017)
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Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/MESIN.2017.26.1.2

Abstract

Rami merupakan salah satu jenis serat alam yang banyak tumbuh di Indonesia dan memiliki sifat mekanik yang baik. Hingga saat ini, pemanfaatan rami sebagai material penguat pada komposit polimer berpenguat serat alam telah banyak dipelajari. Namun, penggunaan serat rami sebagai bahan penguat dan polipropilena high impact (PPHI) yang banyak digunakan dalam industri otomotif sebagai matriks dalam komposit untuk aplikasi di bidang otomotif belum banyak dipelajari. Pada penelitian ini dipelajari pengaruh fraksi volume serat rami terhadap sifat tarik dan sifat impak komposit PPHI berpenguat serat rami. Komposit PPHI dibuat dengan menggunakan injection molding pada temperatur 190 0C dengan fraksi volume serat rami sebesar 5%, 10%, dan 15%. Pengujian densitas dan pengujian fraksi volume bahan penyusun diukur dengan mengacu pada ASTM D 792 dan ASTM D 3171. Kekuatan tarik komposit diukur dengan mengacu pada standar ASTM 3039. Harga Impak dari komposit diukur dengan mengacu pada ASTM D 6110-04. Dari penelitian ini dapat disimpulkan bahwa kekuatan tarik komposit tertinggi dimiliki oleh komposit PPHI berpenguat serat rami dengan fraksi volume serat sebesar 10%, yaitu sebesar 18.17 Mpa, lebih tinggi 21% dibandingkan dengan kekuatan tarik PPHI yang tidak diperkuat oleh serat rami. Harga impak komposit tertinggi juga dimiliki oleh komposit PPHI berpenguat serat rami dengan fraksi volume serat 10%, yaitu sebesar 46.39 KJ/m2, lebih tinggi 15.5% dibandingkan dengan PPHI yang tidak diperkuat oleh serat rami.

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