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Abstrak :
Laporan penelitian ini menyajikan analisa interaksi aliran fluida dengan sebuah model sudu-jalan turbin air kategori `drag type'. Daun sudu-jalan yang dikaji memiliki profil S. Prediksi proses fisik aliran dilaksanakan dengan kaidah komputasi yaitu CFD (Computational Fluid Dynamics). Aliran viskos dua-dimensi disekitar sudu-jalan disimulasikan untuk berbagai kecepatan aliran datang mulai dari angka Reynolds 120 sampai 36000. Hasil-hasil perhitungan detail disajikan dalam bentuk plot-plot vektor kecepatan dan kontur-kontur besar kecepatan, tekanan, tegangan geser dinding untuk kedua arah X data Y. Pengaruh kecepatan aliran datang terhadap distribusi kecepatan, tekanan aliran air dan tegangan geser dinding disekitar dan pada sudu-jalan telah dilaporkan. Hasil-hasil menunjukkan menunjukkan bahwa aliran disekitar sudu-jalan turbin ini dapat disimulasikan secara realistis. Distribusi tekanan yang merupakan data penting untuk rnendapatkan parameter peracangan yaitu hambatan dan angkatan memperlihatkan dengan jelas perbedaan hambatan di kedua daun sudu-jalan. Fenomena aliran beresirkulasi terjadi dibelakang sudu-jalan. Adanya aliran sirkulasi ini berpengaruh terhadap distribusi tekanan dalam medan aliran.

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This research report presents an analysis of interaction of fluid flow and a hydraulic turbine blade model. The physical process of the fluid flow was predicted by means of Computational Fluid Dynamics (CFD). The flow field was numerically observed ranging from Re = 1200 to Re = 36000. The converged solutions are presented in terms of plots of velocity vectors, contours of velocity magnitude, contours of pressure, distributions of wall shear stress in both direction X and Y. Effects of different oncoming flow velocity to the flow field are reported. Results show that the flow field in the vicinity of the turbine blade can be realistically simulated. The calculated pressure distribution indicated drag difference between the advancing and returning blade. The recirculation region formed behind the blade is clearly seen.

Abstrak :
Simulasi CFD (Computational Fluid Dynamic) digunakan untuk mendapatkan perilaku aliran gas buang yang menuju katalis, hasil dari simulasi itu akan digunakan untuk mengoptimasi bentuk geometri diffuser inlet yang akan menghasilkan distribusi aliran yang lebih seragam pada katalis, dan simulasi CFD juga akan digunakan untuk menganalisis penurunan tekanan yang terjadi pada model.

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Diffuser Optimation at Exhaust System with Catalytic Converter for 110 cc Mopet with Fluid Flow CFD Simulation. CFD simulation used to get behavior of exhaust gas through catalyst, this result will be used to optimize geometry form to perform uniform stream distribution to catalyst, and CFD Simulation will used to analyze backpressure that happened at the model.

Abstrak :
As an initial analysis, numerical simulation has more advantages in saving time and costs regarding experiments. For example, variations in flow conditions and geometry can be adjusted easily to obtain results. Computational fluid dynamics (CFD) methods, such as the k-ε model, renormalization group (RNG) k-ε model and reynolds stress model (RSM), are widely used to conduct research on different objects and conditions. Choosing the appropriate model helps produce and develop constant values. Modeling studies as appropriate, i.e., in the turbulent flow simulation in the wind tunnel, is done to get a more accurate result. This study was conducted by comparing the results of the simulation k-ε model, RNG k-ε model and RSM, which is validated by the test results. The air had a density of 1,205 kg/m3, a viscosity of 4×10-5 m2/s and a normal speed of 6 m/s. By comparing the simulation results of the k-ε model, RNG k-ε model and RSM, which is validated by the test results, the third turbulence model provided good results to predict the distribution of speed and pressure of the fluid flow in the wind tunnel. As for predicting the turbulent kinetic energy, turbulent dissipation rate and turbulent effective viscosity, the k-ε model was effectively used with comparable results to the RSM models.