The hydrodynamic thrust bearing is a bearing type that operates on the principle of hydrodynamic lubrication, and it finds extensive application in the power generation sector. The implementation of surface texture engineering techniques on bearing stators has been found to enhance the overall performance of the bearings. Conversely, the adverse impact of roughness creates reduced pressure, hence resulting in cavitation, necessitating its avoidance. The objective of this study is to evaluate the load carrying capacity of two distinct types of textured bearings, taking into account the existence of slip creation at specific areas. The aforementioned locations consist of the pre-pocket, the pocket, and the composite location encompassing both the pre-pocket and the pocket. Furthermore, the simulation includes pockets that maintain a consistent depth, with many adjustments in the minimum film thickness. The result shows the combined slip placement formation has the potential to augment the load carrying capacity. The closed pocket configuration exhibits a maximum increase of 120.3 %, however the circumferential pocket configuration demonstrates a significantly higher enhancement of 178.1 % compared to the no slip condition. The slip effect has the capability to relocate the pressure concentration from the center to the periphery of the pocket when the film thickness is small. The novel design of a closed pocket bearings with a specific slip formation eliminate cavitation, resulting in enhanced bearing performance.

Almost half of municipal solid waste deposited in landfills comprises organic components. Processing organic waste into refuse-derived fuel will enhance the waste's chemical and physical characteristics, making it similar to solid fuel. This fuel can be used as a co-firing mixture in coal-fired power plants. Conversely, utilizing organic RDF (RDF-O) in pulverized coal boilers will cause ash-related problems, such as slagging, fouling, and corrosion, during combustion due to high alkali and chlorine contents. This study discusses the impact of ash problems and RDF-O comprising 5-20 wt% of coal using comprehensive analysisof empirical calculations, ash characteristics analysis, drop tube furnace (DTF) combustion, ash morphology, and mineralogy using SEM-EDS and XRD. The results show that the total chlorine in RDF-O (1985 ppm) increases the total chlorine in the blend samples (228, 323, 418, and 512 ppm), exceeding that in coal (131 ppm). Co-firing coal and RDF-O up to 10 wt% results in clean probe observation, relatively low gas emission, no sintering ash morphology, and minerals with highmelting temperature, indicating that this composition has a low tendency of slagging, fouling, and corrosion. RDF-O 15 wt% sample has small spots in the slagging and fouling probe which indicates there is some potential slagging and fouling tendency. Moreover, the addition of RDF-O up to 20 wt% clearly indicates a serious ashrelated problem as shown on both probes representing slagging and fouling areas.

Journal bearing is a specific type of bearing in which a lubricating liquid separates the inner surface of the bearing from the contacting shaft. Elastohydrodynamic lubrication modeling is a technique used for modeling journal bearing, taking into account the impact of deformation caused by the pressure generated due to the wedge effect resulting from shaft eccentricity during rotation. In this research, CFD software was used to model textured multistep journal bearing while considering the impact of surface roughness on composite material. According to the simulation results, the effect of multistep texture on the journal bearing increased load carrying capacity at low eccentricity ratios and decreased at high eccentricity ratios, while friction force and acoustic power level reduced as the eccentricity ratios increased. In addition, the effect of composite material on lubrication modeling could be observed in the resulting pressure value. In this context, the higher the elastic modulus of the composite material, the lower the pressure due to deformation. Tribological performance was influenced by roughness levels on the bearing surface and tended to decline as roughness value on the bearing surface increased.

The acoustic power level (APL) produced by a thrust bearing during operation has a major effect on its performance. Therefore, this research aimed to investigate the impact of slip engineered on the noise generated by thrust bearings. A numerical approach was used to simulate open pocket bearings with varying film thickness depths. At the initial location of the slip area, three bearing models were analyzed: pocket slip, pocket no slip, and smooth slip. The results show that implementing slip can reduce noise levels, turbulence kinetic energy (TKE), and turbulence eddy dissipation (TED) rate. The average APL, TKE, and TED values were the lowest at the high film thickness

Journal bearing is a machine element that is used to maintain the continuous rotation of the shaft on its axis. The rising demand for efficient and economical journal bearing applications has resulted in increased demand for high-speed machines. An increase in engine speed raises the distribution of pressure, temperature, and vapor volume fraction. Most of the research still only focuses on increasing pressure distribution and load-carrying capacity. However, the value of friction force, temperature distribution, and vapor volume fraction must also be considered such that the lubrication of the journal bearing is close to the real situation. Therefore, the research was conducted by varying the geometry modelling through multistep textures using viscous boundaries and thermo-hydrodynamic lubrication. Owing to the high load and speed usage on multistep journal bearings, research on the effect of eccentricity ratio and inlet and outlet temperatures on the tribological performance of multistep journal bearings was conducted. The analysis has been performed using a multistep journal bearing modelling 3D computational fluid dynamics considering the effect of cavitation on temperature. The results of this study indicate that the use of multistep textures on journal bearings can reduce friction force, temperature, and vapor volume fraction. The variation of the eccentricity ratio shows that a high eccentricity ratio leads to a high three parameters (i.e., friction force, temperature, and vapor volume fraction). Finally, for variations of inlet and outlet temperatures, such parameters are high when the inlet and outlet temperatures are high.

Ethanol has higher octane and oxygen properties than fossil-fuel gasoline. Along with the increase in gasoline dependency and exhaust emissions, the use of ethanol as a fuel is urgently studied. This study aimed to observe the concentration of 5% ethanol in gasoline on the performance and exhaust emissions of a 150cc gasoline engine that was operated at 1000, 2000, and 3000rpm. The observation results show that the concentration of 5% ethanol in gasoline correlates with an increase in performance with indications of an increase in EGT, Brake power, BTE, and a decrease in SFC. On the emission side, it is also correlated with an increase in the quality of exhaust emissions with indications of increased CO2 emissions and reduced CO and HC emissions. The best correlation of 5% ethanol concentration was obtained at an operating speed of 2000rpm with an increase in EGT of 10.70%, an increase in Brake power of 9.49%, an increase in BTE of 38.62%, an increase in CO2 emissions of 23.06%, a decrease in SFC of 26 .49%, CO emission reduction of 16.67%, and HC emission reduction of 4.24%.

The main goal of this research is to evaluate the surface roughness level on the performance of journal bearing using the computational fluid dynamics (CFD) method. Aiming to further enhance the acoustic and tribological lubrication performance, a novel heterogeneous rough/smooth pattern is introduced. The results reveal that increasing the roughness level can improve the load support and reduce the bearing noise. However, an undesirable scenario is observed, namely increased friction force of the heterogeneous rough/smooth bearing.

Lubricated contact performance can be improved by using a textured surface as well as a hydrophobic surface. A procedure to obtain the optimal partially textured journal bearing combined with the hydrophobic coating is presented through the computational fluid dynamics (CFD) codes. In this study, lubricated hydrophobic textured contacts with and without cavitation modeling are discussed. The cavitation phenomena in the lubricant is modeled using a multiphase model of “mixture” to obtain a realistic condition. The effect of dimple depth, as well as the eccentricity ratio, on the tribological performance, is of particular interest. It is found that the tribological performance is greatly influenced by the multiphase flow cavitation scheme. When cavitation modeling is taken into account, higher load support is noted. Furthermore, the simulation results show that a hydrophobic textured surface with a shallow depth (d/hmin<1) seems to be better for enhancing the tribological performance. Meanwhile, for the case of the low eccentricity ratio, there is an optimal dimple depth giving the highest load support. The findings explored in this work can be considered as a theoretical basis to increase the performance of hydrophobic textured journal bearing.

One of the engine components used to reduce friction between two rotating machine elements is the bearing. Currently, studies on the provision of surface roughness on the bearing surface are being conducted to improve its performance. Simplification of surface roughness texture is modeled with various dimple shapes. There is still a paucity of literature dealing with the Reynolds equation in the context of slip and cavitation. This work proposes to utilize numerical analysis to examine the pressure induced by differences in the shape of the dimple. The dimple is portrayed as a triangle with two distinct forms. When approaching the present reality, cavitation is taken into account. Lubricating fluid enters through the dimple on the inlet side and departs through the outlet channel. Slippage is also a factor in computational fluid dynamics simulation. The pressure behavior is determined by varying the Reynolds number. The results show that the higher the Reynolds number, the more pressure is generated. The pressure produced by the triangular dimple shape with high sides at the outlet is greater than the pressure formed by the high-textured dimple at the inlet. The slippage has an impact of 17% on pressure enhancement.

Keausan pada sebuah part dapat dicegah dengan menggunakan pelumas yang tepat, sehingga usia pakai part akan lebih lama. Pelumas SAE 40 biasa digunakan untuk pelumasan engine. Pelumas ini tergolong berviskositas sedang sehingga cocok untuk putaran engine mesin otomotif. Salah satu metode untuk melakukan pengujian terhadap keausan adalah metode pin on disc. Penelitian ini bertujuan untuk mengetahui pengaruh pelumas SAE 40 terhadap keausan besi cor FCD yang bergesekan dengan material bearing dengan pengujian Tribotester Pin-on-Disc. Penelitian ini dilakukan pada material besi cor grafit bulat FCD 50 dan FCD 60 dengan pelumas SAE 40 pada beban 10 N dan 20 N. Pin terbuat dari besi cor digesekkan pada piringan material AISI 52100 yang berputar dalam periode waktu tertentu. Keausan yang terjadi pada pin kemudian diukur lebar keausannya. Dari lebar ini dapat dicari tinggi aus dan volume aus. Hasil penelitian menunjukkan bahwa volume keausan terkecil terjadi pada material pin FCD 60 dengan beban 10 N dan nilai volume keausan terbesar terjadi pada material pin FCD 50 dengan beban 20 N. Dengan membandingkan hasil penelitian ini dengan penelitian sebelumnya, dapat disimpulkan bahwa semakin tinggi nilai viskositas pelumas maka nilai koefisien keausan material akan semakin kecil. Kata kunci: Besi Cor FCD, Keausan, Pelumas, Pin on Disc.

In this paper, the effect of cavitation modeling on the lubrication performance (i.e., load support, friction) is investigated by computational fluid dynamics (CFD) approach.The comparison of the lubrication performance between the analysis with the cavitation model and that without cavitation model is of particular interest.Results are presented for two patterns of textured bearing, i.e., bearing with high inertia and one with low inertia.Based on the simulation results, the inclusion of cavitation modeling has a strong effect of the load support as well as the friction force.The "no-cavitation" cases lead to under-estimation of the predicted performance of lubrication.It is also shown the presence of the inertia is proven to increase the load support.

To reduce a significant energy waste in industry due to the friction and wear in mechanical components, there is an increasing demand for durable thrust bearing under extreme operational conditions.Surface texturing, combined with the application of hydrophobic material, has been proven to be an effective and economical means to enhance the tribological lubrication performance of sliding surfaces.Therefore, in the present work, an exact optimization method is presented to optimize the surface texture in terms of the texture depth for enhancing the loadcarrying capacity.Furthermore, the texture shapes, including ellipse and triangle, are investigated under different arrangements of hydrophobic materials.The lubrication characteristics are established by solving the modified Reynolds equation with means of finite volume method.For modeling the hydrophobic behavior, the critical shear stress model is employed to assure more real boundary conditions of bearing.The simulation results show that for any type of groove shape, the highest load-carrying capacity can be achieved under unique hydrophobic placement.The main interesting finding is the fact that the optimal texture with the groove shape of ellipse shows a better impact on the performance of slider bearing irrespective of the hydrophobic placements.

Pesawat merupakan sarana transportasi yang memiliki arti penting bagi pembangunan ekonomi dan pertahanan, mengingat bahwa Indonesia adalah sebuah Negara kepulauan dengan kondisi geografis yang sulit untuk diakses tanpa sarana transportasi yang memadai. Penelitian ini bertujuan agar mendapatkan koefisiean hinge moment dan side force bidang kendali ekor pesawat N-XXX pada bagian rudder horn dengan variasi defleksi dengan derajat tertentu. Metode yang digunakan untuk analisis aerodinamika ada beberapa macam, yakni metode analisis Computational Fluid Dynamic (CFD) dan eksperimen yang biasa dilakukan dengan uji terowongan angin yang menawarkan tingkat keakuratan hasil lebih nyata namun dengan biaya yang lebih besar. Metode yang digunakan pada penelitian ini adalah analisis dengan metode Computational Fluid Dynamic (CFD). Penelitian dilakukan dengan variasi defleksi pada horn rudder sebesar 0°,10°,20° untuk mengetahui nilai hinge moment dan side force dengan langkah mengidealisasi geometri, meshing dan diselesaikan dengan CFD untuk perhitungannya guna mendapatkan nilai hinge moment dan side force. Pada defleksi 0° mempunyai nilai hinge moment -0.588, defleksi 10° mempunyai nilai hinge moment 0.653 dan defleksi 20° mempunyai nilai hinge moment -3.836 sedangkan untuk nilai side force pada defleksi 0° mempunyai nilai side force -0.999, defleksi pada 10° mempunyai nilai side force 70.908, defleksi 20° mempunyai nilai side force 106.773.Kata kunci: ekor pesawat, defleksi, hinge moment, rudder horn, side force.

Excavator merupakan alat berat yang biasanya digunakan untuk menggali tanah, membelah batu, membongkar jalan atau merobohkan bangunan. Salah satu komponen yang berperan dalam fungsi tersebut adalah bucket tooth. Pada penelitian ini membahas tentang perancangan optimasi bucket tooth yang ada di pasaran untuk menghasilkan desain yang lebih ringan tetapi tetap mempertahankan kekuatannya, bucket tooth tersebut adalah Verona PC200. Proses optimasi pada bucket tooth menerapkan konsep optimasi topologi. Metode yang dilakukan meliputi penentuan jenis material yang dipakai dengan berbagai pengujian yaitu uji komposisi, uji mikrografi dan uji kekerasan. Kemudian dilakukan analisis linear statik menggunakan metode elemen hingga untuk melihat tegangan maksimum yang terjadi pada bucket tooth, besarnya nilai tegangan Von-mises sebesar 403,81 MPa. Selanjutnya dilakukan optimasi topologi dengan memilih beberapa variasi area desain yang menghasilkan reduksi massa dalam variasi pertama sebesar 0,72 kg dan pada variasi kedua 1,49 kg. Reduksi massa tersebut menyebabkan perubahan tegangan yang terjadi pada bucket tooth menjadi 451,8 MPa pada variasi pertama, dan 458,6 MPa pada variasi kedua, namun tegangan tersebut masih dalam kondisi aman.

Dalam teori pelumasan klasik hidrodinamika, asumsi permukaan kontak bearing yang benar-benar halus sering kali digunakan. Meskipun demikian, telah dibuktikan bahwa asumsi tersebut tidak realistis dikarenakan pada umumnya, tidak ada permukaan bearing yang benar-benar halus. Tulisan ini membahas pengaruh kekasaran permukaan terhadap performa slider bearing bertektur dengan menggunakan pendekatan CFD (computational fluid dynamic). Model kavitasi multi-phase digunakan untuk memodelkan fenomena kavitasi yang lebih riil. Performa slider bearing dengan tingkat kekasaran permukaan tertentu dibandingkan dengan slider bearing halus dengan menvariasikan kondisi inersia. Berdasarkan hasil simulasi, ditemukan bahwa tekanan hidrodinamik dan daya dukung beban berkurang dengan bertambahnya kekasaran permukaan. Selain itu, jika bearing dirancang agar memiliki kondisi inersia yang rendah, daya dukung beban akan menjadi lebih besar.