Inertia effect of textured lubricated contact on the bearing performance using CFD approach

Numerous studies reported that inertia of the lubricant has been considered as one of physical parameters which has a strong effect on the load support of textured bearing. In the present study, based on two-dimensional computational fluid dynamics (CFD) technique, the investigatation of the inertia effect on bearing performance is carried out varying the texture length. The Navier-Stokes equation coupled with the cavitation model are discretized using finite volume method and solved using the commercial software FLUENT®. The results show that the inertia increases the hydrodynamic film pressure and thus the load support. In addition, it is also found that increasing the texture length as well as Reynolds number will increase the cavitation region

ANALISIS PENGARUH INERSIA TERHADAP LOAD CARRYING CAPACITY PADA BANTALAN THRUST BERTEKSTUR SEGI EMPAT TUNGGAL DENGAN MEMPERTIMBANGKAN SLIP MENGGUNAKAN METODE COMPUTATIONAL FLUID DYNAMIC (CFD)

Pesatnya perkembangan dalam bidang industri mempengaruhi para peneliti untuk melakukan berbagai macam inovasi. Salah satu penemuan yang menarik dalam bidang pelumasan hydrodynamic adalah desain tekstur pada bantalan thrust. Akan tetapi dengan adanya tekstur pada permukaan bantalan thrust terkadang justru dapat mengakibatkan efek negatif. Oleh karena itu, penelitian ini membahas pengaruh inersia dan rekayasa permukaan slip dalam rangka meningatkan performa bantalan thrustt. Penelitian ini menggunakan metode pendekatan computational fluid dynamic (CFD). Berdasarkan penelitian, diperoleh hasil bahwa slip dapat mengurangi efek kavitasi dengan mereduksi area kavitasi. Sehingga dapat dikatakan bahwa slip mempunyai dampak yang positif terhadap peningkatan performa bantalan thrust salah satunya yaitu dengan meningkatkan load carrying capacity. Sedangkan inersia dikombinasikan dengan slip dapat meningkatkan load carrying capacity akan tetapi panjang daerah kavitasi juga semakin besar

Analysis projectile performance in ballistic tests using compressed air gun

Ballistic resistance is affected by the projectile and armor material used. The character and behavior of the projectile affects its ability to damage and penetrate armor. The velocity, mass and shape of the projectile are the main factors in determining the ability of the projectile to penetrate armor in this case the target plate. Therefore, this study aims to determine and analyze the effect of projectile mass and shape on the velocity with which it penetrates the armor material using a compressed air gun. Armor material as a ballistic test target using carbon steel plate with a thickness of 0.8 mm; 1.2 mm and 1.8 mm. Projectiles of lead materials with different masses and shapes are fired from the air gun under controlled air pressure, set at 2000 Psi, 3000 Psi, and 4000 Psi to provide thrust in the barrel. The plat target is placed at a distance of 5 m from the air gun. Speed gauges are placed after the air gun and after the target plate to determine the projectile's rate before and after passing through the target plate. The test results concluded that the velocity of the projectile ejected from the compressed air gun was influenced by the magnitude of the pressure and the mass of the projectile. The mass of the projectile has a more dominant effect on the velocity of the projectile compared to the amount of pressure applied. Different projectile shapes with the same mass have no significant effect on the velocity. However, the heavier mass projectile outperforms the lighter mass projectile through the target plate. It is required the right combination of velocity and mass of the projectile to be able to penetrate the target plat

Redesigning of 4 (Four) Blades Propeller Installed in a Wooden Fishing Boat in a Ship Yard in Tegal, Central Java Province

For design of marine propeller, the energy supply from marine engine to the propeller should be converted to thrust force with minimum losses. Furthermore, the unwanted vibration and cavitation due to the overlooking a detail calculation of the propeller should be prohibited for increasing the fuel efficiency and life-span of the propeller. In the last few decades, most of small and medium sized enterprises (SMEs) focusing their work on ship component industry in Central Java Province Indonesia provide the marine propeller to the ship manufacturer and ship repairmen in some shipyards in northern part of Central Java port. The design of the propeller is never been observed and optimized. The aim of the present work is to redesign the installed propeller on a wooden fishing boat with the new optimized design using B-Series propeller theory approach. The reverse engineering method uses three-dimensional scanner to obtain the geometrical data of the installed ship propeller. The new optimized propeller design is obtained from free software calculation based on the boat and engine specification. The comparison shows that the new optimized propeller design has a wider blade and larger pitch and increases 20% of the open water efficiency of the propeller performance at lower engine rotation. Keywords: B-series design, fishing boat, marine propeller, redesign, optimizatio

Effect of texture depth on the hydrodynamic performance of lubricated contact considering cavitation

Surface texturing on the lubricated bearing has proven to enhance the hydrodynamic performance. The present work explores the influence of texture parameter as well as the Reynolds number on the tribological performance using computational fluid dynamic (CFD) approach. The inclusion of cavitation model in the analysis of lubrication performance is of particular interest. It is shown that the cavitation has a significant effect on the hydrodynamic pressure, and thus the cavitation model should be considered in analysis. Moreover, in this study the optimal relative texture depth is discussed in more detail regarding with the cavitation effec

Pengaruh Pemodelan Kavitasi untuk Analisis Kontak Terlubrikasi dengan Slip Dinding

Kondisi no-slip pada umumnya dianggap sebagai kondisi batas pada antarmuka antara pelumas dan permukaan dinding sampai akhir abad ini. Namun terbukti secara eksperimental bahwa slip terjadi pada permukaan baik hydrophobic maupun hydrophilic. Kondisi Navier-slip sering diusulkan sebagai pengganti kondisi batas. Meskipun demikian, dalam beberapa penelitian yang telah dipublikasikan, analisis performansi pelumasan dengan slip masih mengasumsikan bahwa kavitasi tidak terjadi. Tujuan dari penelitian ini adalah mengetahui pengaruh pemodelan kavitasi dalam analisa performansi pelumasan dengan slip. Performansi pelumasan yang ditinjau meliputi daya dukung pelumasan dan gaya gesek. Persamaan Reynolds yang dimodifikasi dikembangkan untuk mencari distribusi tekanan dalam kontak. Metode beda hingga digunakan untuk mendiskretisasi persamaan Reynolds dan pemecahannya dilakukan dengan menggunakan Tri-Diagonal Matrix Algorithm (TDMA). Model kavitasi yang digunakan adalah Half Sommerfeld (HS) dan Swift-Stieber (SS) pada aplikasi slider bearing dengan permukaan paralel. Hasil penelitian menunjukkan bahwa model kavitasi HS dan SS memiliki pengaruh yang signifikan dibanding dengan analisis tanpa kavitasi. Dengan pemodelan kavitasi, hasil analisis pelumasan menjadi lebih realistis karena dapat meniadakan harga negatif pada tekanan kontak dan daya dukung pelumasan. Oleh karena itu, dalam analisis heterogen, direkomendasikan untuk menggunakan model kavitasi dalam analisis. Kata Kunci: slider bearing, slip, metode beda hingga, model kavitas

Effect of inertia on the cavitation phenomena of hydrodynamic textured bearings considering slip

Surface modification of a lubricated bearing, such as hydrophobic coating inducing slip situation and texturing, is proved to enhance hydrodynamic performance. As widely known, in textured surface lubricant inertia and cavitation can significantly affect the hydrodynamic pressure profile. However, a brief literature review indicates that studies related to the correlation between cavitation and inertia, especially in the presence of slip, are considerably limited. The present study examines the effect of inertia on cavitation phenomena by considering the slip boundary using two approaches, namely computational fluid dynamics based on full Navier–Stokes equations and analytical lubrication equation based on the Reynolds equation. The modified Reynolds equation with slip concept is used with respect to the slip effect applied on the surface of the bearing. The results indicate that the inertia as well as the slip condition significantly affects the cavitation area. It is also highlighted that the cavitation area reduces by increasing the inertia effect, and it becomes smaller when the slip is introduced