Kajian Eksperimen Dan Numerik Pengaruh Silinder Sirkular Terhadap Kinerja Turbin Air Savonius Sumbu Vertikal

Setiawan, Priyo Agus (2020) Kajian Eksperimen Dan Numerik Pengaruh Silinder Sirkular Terhadap Kinerja Turbin Air Savonius Sumbu Vertikal. Doctoral thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Daya air (Hydropower) dari aliran sungai atau arus laut merupakan salah satu sumber renewable terbaik. Energi arus air merupakan sumber daya alam yang dapat diperoleh secara cuma-cuma yang jumlahnya melimpah dan tersedia terusmenerus sepanjang tahun. Indonesia merupakan daerah kepulauan dan memiliki potensi pengembangan energi yang cukup tinggi. Potensi arus sungai rata-rata kedalaman 2 m di perairan Indonesia berada pada kisaran 0,12-0,32 m/s. Turbin yang sesuai untuk kecepatan arus sungai rendah adalah turbin Savonius. Penelitian ini bertujuan untuk meningkatkan kinerja turbin air Savonius, yang berarti peningkatan torsi positif turbin. Peningkatan torsi positif turbin dengan cara meletakkan silinder sirkuler di depan atau di samping sudu advancing untuk meningkatkan gaya drag pada sudu advancing, atau di depan sudu returning untuk mengurangi gaya pada sudu ini. Penelitian ini menggunakan metode numerik dan eksperimen. Numerikal dilakukan untuk melihat visualisasi aliran yang tidak dapat dilakukan oleh eksperimental. Numerikal dilakukan dengan melakukan verifikasi dan validasi terhadap data eksperimental yang sudah dipublikasikan. Pemodelan numerik dilakukan untuk melihat pengaruh silinder terhadap torsi dan daya turbin Savonius. Pemodelan numerikal dengan menggunakan Reynolds Averaged Navier – Stokes (RANS) dengan deskritisasi second order upwind dan jenis turbulence model Realizable k epsilon (RKE). Eksperimental dilakukan pada flowing tank dengan ukuran tinggi air 900 mm dan lebar channel 1100 mm. Diameter savonius berukuran 400 mm dan kecepatan arus sebesar 0,22 m/s. Parameter yang berpengaruh dalam penelitian ini adalah diameter silinder sirkular terhadap diameter turbin Savonius (ds/D), Jarak (X/D), sudut stagger () di depan advancing blade dan sudut stagger (α) di depan returning blade. Pemasangan silinder sirkular dilakukan pada sisi advancing blade dan returning blade. Hasil Numerikal menunjukkan bahwa penempatan silinder sirkular pada sisi samping advancing blade dengan variasi diameter silinder menunjukkan kinerja terbaik pada diameter ds = 0,7D dengan kenaikan kinerja sebesar 25,10 % pada TSR 0,7. Penempatan silinder pada sisi samping advancing blade pada variasi jarak horizontal (x/D) terbaik pada x = 0,5D dengan kenaikan kinerja sebesar 17,31 % pada TSR 0,9. Penempatan silinder sirkular pada variasi stagger di depan advancing blade menunjukkan koefisien daya atau kinerja terbaik terjadi pada sudut stagger 60o dengan kenaikan kinerja sekitar 15,82% pada TSR 0,9. Penempatan silinder sirkular pada variasi stagger di depan returning blade menunjukkan kinerja terbaik pada stagger 60o dengan kenaikan kinerja sekitar 11,74 % pada TSR 0,9. Sedangkan Hasil eksperimen dan numerik menunjukkan tren hasil yang sama. ========================================================= Hydropower from rivers or marine currents, tides and irrigation canal is one of the best renewable sources. The energy of water flow is a natural resource that can be obtained free of charge and is available continuously throughout the year, and environmentally friendly. As an archipelagic country, Indonesia has the potential for high water energy development. The potential for river currents with an average depth of 2 (two) meters in Indonesian waters ranges from 0.12 - 0.32 m/s. For this low water flow rate, the Savonius type water turbine is most suitable. The low performance of the Savonius turbine compared to other types of turbines has inspired this research to make improvements to its performance. This study aims to improve the performance of the Savonius water turbine, which means an increase in the positive torque of the turbine. The increase in the positive torque of the turbine is done by placing a circular cylinder in front of or beside the advancing blade to increase the drag force on the advancing blade, or in front of the returning blade to reduce the force on the blade.This research uses numerical and experimental methods. The numerical method used is intended to visualize flow phenomena that cannot be determined experimentally. The numerical results are verified and validated by published experimental data. Numerical modelling using Reynolds Averaged Navier - Stokes (RANS) with descriptive second-order upwind and Realizable k-epsilon (RKE)turbulence model was carried out to investigate the effect of the cylinder on the torque and power of the Savonius turbine. The experiment was carried out on an flowing tank with a water height of 900 mm and a channel width of 1100 mm. Savonius turbine blade diameter measuring 400 mm. The speed of the water flow is adjusted according to the capability of the equipment of velocity measurement of 0.22 m/s. The important parameters in this study are the diameter of the circular cylinder (ds) and the distance between circular cylinder and advancing blade (X) calculated relative to the turbine diameter are (ds/D) and (X/D), respectively, and also the angle of the stagger () in front of the advancing blade and the angle of the stagger (α) in front of the returning blade. The Circular cylinder installation is performed in front and beside of the advancing blade, and in front of the returning blade. The numerical results show that the placement of a circular cylinder measuring ds = 0.7 D on the side of the advancing blade gives the highest increase in the power coefficient of the turbine, which is 25.10% at TSR = 0.7. The placement of the cylinder on the side of the advancing blade at a horizontal distance of x = 0.5D gives the highest performance increase, which is 17.31% at TSR = 0.9. The placement of circular cylinder in the stagger variation in front of the advancing blade shows that the best power coefficient of turbine occurs at a stagger angle of 60o with an increase in the power coefficient of about 15.82% at TSR = 0.9. Meanwhile, the placement of circular cylinders on the stagger variation in front of the returning blade shows the best performance on the 60o stagger with an increase in power coefficient of about 11.74% at TSR 0.9. Furthermore, the comparison between the experimental and numerical results shows the agreement of each other.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: performance, circular cylinder, Savonius, hydropower, advancing blade, returning blade. Kinerja, Silinder sirkular, Savonius, hydropower, advancing blade,returning blade.
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ266 Turbines. Turbomachines (General)
Divisions: Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21001-(S3) PhD Thesis
Depositing User: PRIYO AGUS SETIAWAN
Date Deposited: 16 Sep 2020 01:30
Last Modified: 16 Sep 2020 01:30
URI: https://repository.its.ac.id/id/eprint/81879

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