Hasil Pencarian  ::  Simpan CSV :: Kembali

"Pendekatan eksperimen dan model simulasi telah dilakukan untuk mengetahui perilaku partikel halus yang menempel pada lapisan cairan di dinding dalam aliran dua fase gas padat. Polimetil metaklirat dengan diameter 20 um dan 50 um digunakan pada pengukuran ini. Dengan menggunakan sistem pengumpan kontinyu, partikel halus dimasukkan dan dicampur dengan udara di dalam ducting. Eksperimen aliran dua fase dengan gas dan partikel halus padat dalam temperatur ruangan telah dilakukan untuk mengamati efek penempelan partikel yang menempel di dinding yang memiliki lapisan cairan dengan viskositas tinggi. Hasil percobaan menunjukkan bahwa kuantitas partikel melekat tergantung pada kecepatan pengumpanan partikel. Hasil model simulasi juga menunjukkan kecenderungan yang sama. Hubungan laju pengumpanan bermacam-macam partikel dan tingkat penangkapannya dibahas disini."

"A single phase, incompressible turbulent flow through a 90º pipe bend with/without guide vane conditions has been studied here. The present work deals with the numerical simulation to investigate the change in flow separation and velocity distribution at the downstream section due to the effect of the guide vane. The k-? turbulence model has been adopted for simulation purposes to obtain the results. After the validation of existing experimental and numerical results, a detailed study has been performed for three different Reynolds number and four different positions of the guide vane. The value of the Curvature ratio (Rc/D) has been considered as one factor for the present study. The curvature ratio can be defined as the ratio between the bend curvature radius and hydraulic diameter of the pipe. The results obtained from the present study have been presented in graphical form. A flow separation region has been found at the bend outlet for flow through 90º pipe bend without the guide vane. This flow separation region was absent for the cases which dealt with the flow through 90º pipe bend with the guide vane. Velocity distribution at four different downstream positions for different cases and different Reynolds numbers have been compared and reported in the present study."

"This is the proceedings of the Second International Workshop on Flow Induced Noise and Vibration (FLINOVIA), which was held in Penn State, USA, in April 2016. The authors’ backgrounds represent a mix of academia, government, and industry, and several papers include applications to important problems for underwater vehicles, aerospace structures and commercial transportation. The book offers a valuable reference guide for all those working in the area of flow-induced vibration and noise.Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field.The book describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation; for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays; for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements; for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses."

""Callister and Rethwisch?s Fundamentals of Materials Science and Engineering, 4th Edition continues to take the integrated approach to the organization of topics. That is, one specific structure, characteristic, or property type at a time is discussed for all three basic material types -- metals, ceramics, and polymeric materials. This order of presentation allows for the early introduction of non-metals and supports the engineer?s role in choosing materials based upon their characteristics. Also discussed are new, cutting-edge materials. Using clear, concise terminology that is familiar to students, Fundamentals presents material at an appropriate level for both student comprehension and instructors who may not have a materials background"-- Provided by publisher."

"Perkembangan penelitian tentang aktuator plasma khususnya dalam aplikasi kontrol aliran terus berkembang pesat dalam dekade belakangan ini. Kemampuan aktuator plasma yang dapat bekerja tanpa adanya bagian yang bergerak secara mekanik atau fleksibel dan konsumsi energi yang sedikit menjadi keunggulan tersendiri jika dibandingkan dengan peralatan kontrol aktif yang sebelumnya telah digunakan seperti blowing, suction, dan jet sintetik. Aktuator plasma adalah susunan beberapa material yang terdiri dua buah lembaran tembaga sebagai elektroda yang diantaranya terdapat sebuah dielektrik material sebagai penahan medan listrik. Kedua elektroda tersebut dihubungkan dengan transformer bertegangan tinggi yang memiliki keluaran 5500-volt dengan rasio 137.5 dengan jenis step-up. Dalam melakukan modifikasi atau rekayasa suatu aliran ada beberapa metode yang umum digunakan yaitu modifikasi laminar ke transisi turbulen, separasi dan turbulen. Metode-metode tersebut dapat terapkan dengan baik dengan melakukan perubahan pada lapisan batas di setiap perubahan rezim alirannya. Pada penelitian ini dilakukan kajian untuk mendapatkan pemahaman terhadap modifikasi struktur aliran turbulen dengan memanipulasi kondisi lapisan batas yang terbentuk pada plat datar dengan mengunakan turbulen promoter sebagai pemicu meningkatan turbulensi aliran pada lapisan batas. Penelitian ini dilakukan secara eksperimen dan komputasi untuk mendapatkan fenomena yang lebih riil dan komprehensif. Secara eksperimen, penggunaan aktuator plasma pada kondisi tanpa aliran free stream memberikan kemampuan menghasilkan angin ion maksimal sebesar 1.2 m/s dan dengan mengunakan aliran free stream sebesar 2 m/s dapat mereduksi tebal lapisan batas sebesar 9 mm. Secara komputasi, diketahui bahwa aktuator plasma bekerja menginduksi suatu aliran karena pengaruh dari medan elektromagnetik dengan membentuk efek body force di sekitar aktuator. Pemodelan body force dikembangkan sebagai pengembangan model numerik untuk mengembangkan model komputasi dalam fluid mechanics. Dari hasil pemodelan numerik tersebut didapatkan persamaan body force yang bekerja untuk aktuator plasma dengan eror 2 jika dibandingkan dengan hasil pengukuran kecepatan secara eksperimen.

---

The research development in plasma actuator especially in its application of flow control keeps rapidly expanding in the past decades. The ability of plasma actuator which can work without any mechanically moving parts or flexible and the little amount of energy consumption that it needs have been a unique advantage if compared to other past active control devices such as blowing, suction, and synthetic jet. Plasma actuator is a configuration of few materials, which consists of two copper plates as the electrodes with a dielectric material in between as the electrical field resistor. Both electrodes then were connected to the high voltage transformer with the output of 5500 volt and the ration of 137.5. The type of the transformer itself is a step up transformer. In the effort of modifying or altering the flow, there are few methods which generally being used modifying laminar to trubulent transition, separation, and turbulent. Those methods can be implemented by altering the flow on its boundary layer in each flow rezime. This research focuses in the study of acquiring an understanding in the modification of the turbulent flow structure by manipulating the boundary layer condition which formed on the flat plate using the turbulent promoter as the trigger to form the boundary layer. This research was conducted experimentally and computationally to obtain the more real and comprehensive phenomenon. In the experimental result, it is obtained that the usage of plasma actuator on the condition without the free stream flow can achieved the ability to generate the maximum ionic wind of 1.2 m s. Meanwhile, in the condition with 2 m s free stream velocity, plasma actuator can decrease the boundary layer thickness up to 9 mm. In the computational result, it is known that plasma actuator works by inducting the flow due to the effect of electromagnetic field by forming the body force effect around the actuator. The body force modelling later was developed as numerical model development to develop the simulation model in fluid mechanics. From this numerical modelling, the body force equation is later obtained that can be applied into plasma actuator with an error of 2 , if compared with the result of velocity measurement which obtained experimentally."

"Komposit Al/SiCp coating telah dihasilkan dari gravity casting. Dengan partikel SiC dilapisi oleh lapisan metal oksida yang diperoleh dari proses electroless plating dalam larutan elektrolit HNO3, dengan konsentrasi magnesium (Mg) dalam larutan elektrolit tersebut bervariasi dari 0,002 sampai 0,012 mol dan konsentrasi aluminum (Al) dibuat tetap 0,018 mol. Partikel SiC coating tersebut, digunakan untuk membuat komposit (MMCs) dengan persen volume SiC bervariasi dari 2 sampai 20,5 vol%. Komposit aluminum yang dihasilkan, dianalisis dalam metalografi dan sifat mekanik. Dari komposit tersebut, diperoleh bahwa sifat mekanik komposit dapat meningkat dibandingkan dengan matriks aluminum, seperti kekerasan meningkat dari 76,23 BHN menjadi 96,82 BHN, porositas turun dari 8,97% menjadi 3,81% dan laju keausan turun dari 10,6 x 10-6/mm/mm3 menjadi 2,63 x 10-6/mm/mm3 karena penambahan persen volume SiC 15%. Sedangkan kuat tarik komposit Al/SiCp turun dibandingkan dengan matriks aluminumnya dari 203,31 Mpa menjadi 191,49 Mpa. Pembentukan fasa spinel MgAl2O4 di interface Al/SiC rendah, karena magnesium berinteraksi dengan silikon, membentuk fasa baru Mg2Si yang teridentifikasi oleh XRD pada semua komposisi persen volume SiC coating. Pembentukan fasa Mg2Si pada matriks aluminum, dapat meningkatkan sifat mekanis komposit Al/SiCp.

---

Al/SiCp coating MMCs has been produced by gravity casting. The SiC particles were coated with metal oxide film obtained by electroless plating in liquid electrolyte HNO3, and liquid electrolyte made various magnesium (Mg) concentrations from 0.002 to 0.012 mole and a concentration aluminum (Al) have made constant is 0,018 mole. The SiCp coated, used for making MMCs was various volume percent SiCp from 2 to 20.5 vol%. The aluminum composites produced was analysed both metalography and mechanical properties. It is obtained that mechanical properties of these composites are increased compared to unreinforced, i.e hardness increased from 76.23 BHN to 96.82 BHN, porosity decreased from 8.97% to 3.81% and wear rates decreased from 10.6 x 10-6/mm/mm3 to 2.63 x 10-6/mm/mm3 due to the additions volume percent SiC up to 15%. In contrast, the tensile strength of Al/SiCp composites decreased from 203.31 MPa to 191.49 MPa. Spinel phase of MgAl2O4 at the interface Al/SiC is low, due to magnesium interact with silicon, formed a new phase of Mg2Si indentified by XRD in all composition of volume percent SiC coating. A new phase of Mg2Si formed in the matrix aluminum, increased mechanical properties of Al/SiCp composites."