STUDI EKSPERIMENTAL MENGENAI VISUALISASI DAN KARAKTERISTIK ALIRAN FLUIDA DUA FASE (AIR-UDARA) PADA DOWNSTREAM RECTANGULAR T-JUNCTION MINICHANNEL DENGAN METODE IMAGE PROCESSING

Muhammad Rifqifauzi Wijaya, Prof. Dr. Ir. Indarto, DEA

2020 | Skripsi | S1 TEKNIK MESIN

Studi eksperimental mengenai aliran fluida dua fase air dan udara dilakukan pada seksi uji rectangular T-Junction minichannel berukuran 1,25 mm x 2,25 mm dengan DH sebesar 1,6 mm searah horizontal. Variasi kecepatan superfisial fluida cair dan gas yang digunakan secara berturut yakni JL = 0,7 m/s - 4,935 m/s dan JG = 0,871 m/s � 58,05 m/s. Fluida kerja yang digunakan air dan udara. Seksi uji yang digunakan menggunakan bahan dasar akrilik untuk memudahkan pengamatan pola aliran secara visual. Pada eksperimen kali ini dilakukan pengamatan terhadap berbagai karakteristik aliran fluida dua fase diantaranya yakni pola aliran, peta pola aliran, karakteristik pola aliran slug (panjang slug, kecepatan slug, dan frekuensi slug), serta karakteristik gradien tekanan (dp/dx) pada masing-masing pola aliran yang berhasil diamati pada bagian downstream dari T-Junction dengan menggunakan analisis statistik berupa time series dan Probability Distribution Function (PDF). PDF digunakan untuk mengetahui karakteristik distribusi gradien tekanan (dp/dx). Data pola aliran diperoleh dengan mengamati hasil video pola aliran yang ditangkap dengan menggunakan kamera berkecepatan tinggi Phantom Miro M310. Panjang dan kecepatan slug diolah dengan metode image processing menggunakan software MATLAB R2016a. Sedangkan, data gradien tekanan (dp/dx) diperoleh dengan menggunakan sensor P55 Valydine Differential Pressure Transducer yang terpasang pada bagian main inlet fluida air, short inlet fluida udara dan outlet di daerah downstream dari seksi uji T-Junction. Dari hasil penelitian didapatkan bahwasanya pola aliran yang berhasil diamati pada daerah downstream dari seksi uji yakni pola aliran bubble, slug, slug annular, dan churn, sedangkan pola aliran stratified dan annular tidak berhasil diamati. Dari beberapa peta pola aliran yang ada, peta pola aliran yang mirip dengan penelitan ini terjadi pada beberapa daerah pola aliran saja yakni peta pola aliran Triplett dkk (1999) hanya pada daerah pola aliran slug, peta pola aliran Elazhary dan Soliman (2012) hanya pada daerah pola aliran slug. Sedangkan peta pola aliran Mandhane cukup signifikan perbedaannya pada daerah pola aliran dan batas transisinya Selain itu, kecepatan superfisial fluida memiliki pengaruh yang signifikan terhadap panjang, kecepatan dan frekuensi kemunculan gas slug. Seiring dengan meningkatnya JL saat JG konstan, didapatkan panjang gas slug menurun sedangkan kecepatan gas slug dan frekuensi kemunculan gas slug meningkat. Seiring dengan meningkatnya JG pada JL konstan, panjangxxii gas slug meningkat, kecepatan gas slug meningkat sedangkan frekuensi gas slug menurun. Dari hasil penentuan karakteristik gradien tekanan (dp/dx) antara daerah upstream yakni pada bagian main inlet fluida air dan short inlet fluida udara terhadapoutlet pada daerah downstream T-Junction dengan menggunakan analisis time series dan PDF didapatkan bahwasanya seiring dengan meningkatnya kecepatan superfisial fluida air dan udara, fluktuasi gradien tekanan (dp/dx) akan semakin meningkat pada pola aliran bubble, slug, slug annular dan churn ditunjukkan dengan grafik PDF yang semakin landai.

Experimental study of gas-liquid co-current two-phase flow in a minichannel in horizontal direction were conducted. The test section was rectangular T-Junction minichannel test section sized 1,25 mm x 2,25 mm with DH of 1,6 mm made from acrylic material to facilitate visual observation of flow pattern. The range of gas and liquid superficial velocities were JL = 0,7 m/s - 4,935 m/s and JG = 0,871 m/s � 58,05 m/s, respectively. The working fluids were air and water. In this experiment, observation were made on various of two-phase fluid flow including flow pattern, flow pattern map, slug flow pattern characteristics (slug length, slug velocity, and slug frequency), as well as the pressure gradient characteristics of each flow pattern which observed in the downstream area of the T-Junction using statistical analysis in the form of time series and Probability Distribution Function (PDF). PDF is used to determine the characteristics of the pressure gradient ditribution. Flow pattern data were obtained by observing the results of the flow pattern video captured using a high-speed camera, Phantom Miro M310. The slug length and slug velocity data were processed by image processing method using MATLAB R2016a software. Meanwhile, the pressure gradient data were obtained using the P55 Valydine Differential Pressure Transducer sensor which is attached to the main inlet of water, short inlet of air in the upstream area and outlet in the downstream area of the T-Junction test section. From the experiment result showed that the flow pattern observed in the downstream rea of the test section were bubble, slug, slug annular, and churn, while the stratified flow pattern and annular were not observed. From several existing flow pattern maps, flow pattern maps similar to this research occur in only a few flow pattern areas, namely the flow pattern map of Triplett et al. (1999) only in the slug flow pattern area, Elazhary and Soliman (2012) flow pattern map only in the slug flow pattern area. Meanwhile, when compared to the Mandhane flow pattern map, the differene is quite significant in the flow pattern area and the transition boundary. In addition, the superficial velocity of the fluid has a significant effect on the length, velocity and frequency of apperance of the gas slug. As the JL increases while JG keep constant, the length of the gas slug decreased, while the gas slug velocity and the frequency of apperance of the gas slug increased. As the JG increases at constan JL, the gas slug velocity increase while the gas slug frequency decreases. From the result of determining the characteristics of thexxiv pressure gradient between the upstream area, namely the main inlet of the water fluid and the short inlet of air fluid to the outlet in the downstream area of T-Junction using time series and PDF analysis, it was found that along with the increasing superficial velocity of water and air fluid, pressure gradient fluctuation will increase in each flow pattern (bubble, slug, slug annular, and churn).

Kata Kunci : Multiphase fluid flow, T-Junction, minichannel, flow pattern, flow pattern map, pressure gradient, PDF