Septyaningrum, Erna (2024) Analisa Struktur Aliran pada Gravitational Vortex Water Turbine (GVWT) – Dual Stage. Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Gravitational Vortex Water Turbine (GVWT) merupakan jenis turbin yang didesain untuk lokasi dengan head dan flowrate rendah, dengan rentang opetasi 0,7 - 2 m. Kinerja GVWT dipengaruhi oleh beberapa parameter desain, seperti kanal, basin dan runner. Runner propeller dipilih untuk diaplikasikan dalam GVWT karena memiliki efisiensi dan RPM yang tinggi. Upaya yang dapat dilakukan untuk meningkatkan kinerja GVWT adalah dengan menambahkan guide vane dan menyusunkan dalam konfigurasi dual stage. Penelitian terkait GVWT telah banyak dilakukan sebelumnya. Namun analisa terhadap fenomena aliran dan kinerja GVWT dengan runner propeller belum dilakukan. Penelitian ini bertujuan untuk menganalisa kinerja GWVT dan fenomena aliran yang terjadi di dalam basin. Penelitian ini menganalisa kinerja dan detail fenomena aliran pada GVWT, baik untuk GVWT single stage (SS), single stage dengan guide vane (SS-GV) dan double stage (DS), dengan menggabungkan metode Experimental Fluid Dynamics (EFD) dan Computational Fluid Dynamics (CFD). Metode EFD dilakukan untuk melihat kinerja GVWT (data RPM dan torsi), yang dilakukan dengan menggunakan fasilitas flume tank. Sementara metode CFD bertujuan untuk menganalisa fenomena aliran yang terjadi di dalam basin. CFD dilakukan pada model 3D, dengan menggunakan model turbulensi RNG k-ε. Metode volume of fluid (VOF) dipakai untuk memodelkan free surface. Analisa profil, kontur, vektor dan streamline dilakukan untuk lihat fenoma aliran yang muncul. Hasil penelitian menunjukkan bahwa GVWT yang diuji memiliki nilai efisiensi yang cukup baik GVWT SS memiliki efisiensi mencapai 42%. Modifikasi intake kanal dan konfigurasi turbin dilakukan untuk meningkatkan efisiensi GVWT SS, yaitu dengan penambahan guide vane (GVWT SS-GV) dan instalasi dual stage runner (GVWT DS). Efisiensi GVWT SS-GV mencapai 49.24%, yang meningkat akibat penyesuaian sudut aliran, peningkatan vortex height dan peningkatan kecepatan tangensial. GVWT DS dengan pergeseran sudut azimuth 15° (GVWT DS-15) bekerja dengan efisiensi 55%, akibat peningkatan kecepatan tangensial dan penyesuaian sudut aliran. Sementara itu, penggunakan runner DS dan penambahan guide vane menyebabkan munculnya secondary flow yang lebih kompleks. Adanya runner yang berputar dan posisi outlet yang dekat dengan runner, menyebabkan secondary flow tertarik memanjang ke arah downstream atau outlet. Sementara itu, analisa non dimensional telah dilakukan untuk mendapatkan persamaan prediksi daya untuk masing-masing konfigurasi.
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The Gravitational Vortex Water Turbine (GVWT) is a type of turbine designed for locations with low head and flow rate, typically ranging from 0.7 to 2 m. The performance of GVWT is influenced by several design parameters such as the channel, basin, and runner. The propeller runner is chosen for GVWT application due to its high efficiency and RPM. Two methods for enhancing the GVWT performance are adding guide and arranging them in a dual-stage configuration. The research related to GVWT has been extensively conducted previously. However, analysis of the flow phenomena and performance of GVWT with a propeller runner has not been carried out. This study aims to analyze the performance of GVWT and the flow phenomena occurring within the basin.
This research analyzes the performance and detailed flow phenomena in GVWT, both for single-stage GVWT (SS), single-stage with guide vane (SS-GV), and double-stage (DS), by combining Experimental Fluid Dynamics (EFD) and Computational Fluid Dynamics (CFD) methods. The EFD method is employed to observe the performance of GVWT (RPM and torque data) using a flume tank facility. Meanwhile, the CFD method aims to analyze the flow phenomena occurring within the basin. CFD is conducted on a 3D model using the RNG k-ε turbulence model. The Volume of Fluid (VOF) method is used to model the free surface. Analysis of profiles, contours, vectors, and streamlines is conducted to observe the emerging flow phenomena. The findings indicate that the tested GVWT achieves a reasonably good efficiency, the performance of GVWT SS is approximately 42%. Modifications is conducted to improve GVWT SS efficiency, such as adding guide vanes (GVWT SS-GV) and installing double-stage runners (GVWT DS), result in efficiencies of 49.24% and 55% for GVWT SS-GV and GVWT DS-15 (DS with a 15° azimuthal angle shift), respectively. These improvements are attributed to adjustments in flow direction (angle of attack), increased vortex height, and enhanced tangential velocity. Additionally, the use of DS runners and guide vanes introduces more complex secondary flows. The rotating runner and close outlet position attract elongated secondary flows downstream. Non-dimensional analysis has also been conducted to derive power prediction equations for each configuration.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | deflektor, dual stage, guide vane, GVWT, propeller, secondary flow, single stage. |
| Subjects: | Q Science > QC Physics > QC151 Fluid dynamics |
| Divisions: | Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21001-(S3) PhD Thesis |
| Depositing User: | Erna Septyaningrum |
| Date Deposited: | 23 Aug 2024 01:52 |
| Last Modified: | 23 Aug 2024 01:52 |
| URI: | http://repository.its.ac.id/id/eprint/115491 |
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