Previous numerical studies in the Savonius wind turbine mostly used constant angular velocity as input data, where the values were obtained from experiments. This process cannot be used in the design optimization of the turbine, in which the angular velocity of the modified turbine is not known a priority. In numerical simulation, the use of loading system to get constant angular velocity to control the tip speed ratio (TSR), tends to have fluctuating value on output data. Moreover, the values of angular velocity shall be the results from freestream flow and Savonius rotor interaction. This condition can be simulated by using fluid structure interaction (FSI) method. Three dimensional Savonius S wind turbine is simulated using unsteady Reynolds Averaged Navier Stokes (RANS). Inlet velocity and wind turbine inertia are used as input data. The flow is assumed to be incompressible, viscous, and uniform at the inlet. The turbulence model used is the Eddy Viscosity k-ω SST, with y+ < 1. The domain consists of a sliding mesh, which rotates in the overset mesh region. Simulation results Power Coefficient (CP) and angular velocity and compared with experimental result. This study is resulted a standard method for the Savonius wind turbine numerical study.
Katup merupakan peralatan mekanik statis yang bertujuan untuk mengontrol aliran dan tekanan dalam suatu sistem perpipaan. Pemilihan jenis katup, bentuk desain dan jenis material memiliki peran yang sangat penting dalam kinerja dan kehandalan sistem. Pompa hidram bekerja dengan memanfaatkan proses palu air. Terjadinya palu air akan mengakibatkan sebagian air menuju ke tabung udara dan sebagian lagi akan mengalami aliran balik pada pipa penggerak. Pencegahan water hammer bisa dengan cara pemasangan check valve, relief valve, menambah waktu pembukaan dan penutupan valve. Oleh karena iu pada penelitian ini akan digunakan variasi beban dan bentuk katub limbah terhadap efek water hammer Penelitian ini menggunakan variasi katup limbah champfer,normal dan fillet. Hasil penelitian menunjukan bentuk disk champfer dengan berat beban 200 gram memliliki kecepatan aliran tertinggi yaitu 0,72752 m/s dengan nilai Reynold 18479,21. Sedangan variasi bentuk disk fillet memili nilai kecepatan terrendah dengan nilai 0.48276 m/s dengan nilai reynold 12262,29.
The design of the exhaust system affects many parameters such as reducing the noise level, control velocity, temperature, back-pressure of exhaust gas and reduce pollution production. The exhaust system has many parts which consist of an exhaust manifold, resonator, catalytic converter, muffler, and connecting pipes. Muffler has the main function as a noise absorber. Furthermore, the temperature distribution on mufflers is also affected by fuel consumption by reducing back-pressure effect. This study has conducted an experiment to determine the effect of modified muffler shape in a motorcycle which consists of standard, scorpion, and 3v3 type. The effects of mufflers’ performance on the motorcycle are described on torque and power graphics. Furthermore, this study explains the muffler geometry effect on noise reduction from the combustion process. The installation of 3v3 muffler decreases torque and power in a motorcycle. Moreover, the installation of 3v3 muffler type raises noise pollution level which generates by the engine combustion process.
Aerodynamic forces that occur around the vehicle must be considered since it involves safety, ergonomic, and fuel consumption. To reduce fuel consumption, the vehicle should be built as aerodynamic as possible to minimize drag forces. The vehicle becomes unstable at high speed due to increasing lift force. To balance the vehicle at high speed, a downforce should be generated to keep the tires attached to the road surface. Each type of car has a various value of aerodynamic force due to its design, dimension, and cross-section area. The characteristics of streamflow around the car are discussed in this paper. This research simulated 2D sedan car YRS 4 Doors in the steady condition in various velocities, i.e. 23 m/s, 26 m/s, and 40 m/s. This simulation used the Quad Pave mesh model and run in k-ε implicit turbulence model. The characteristics could be observed from the qualitative and quantitative data. The quantitative data used as measurable data were Coefficient of Pressure (CP) and Drag Coefficient (CD). Quantitative data was shown to outline a better visual explanation of the streaming characteristic. The qualitative data used in this paper are path lines, velocity vectors, and contours. The high-velocity stream results in a low value of CP. When the fluid flowed at high speed through a surface, it had low pressure. The coefficient of drag in the high-speed car decreased as the free stream increased. The value of the coefficient of drag (Cd) from this research was app. 0.567.
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