Nugraha, ArifYunizar (2014) Simulasi Komputasi dan Verifikasi Eksperimen Aliran Fluida Dua Fase (Air-Udara) di Belokan 90°. Magister thesis, Universitas Brawijaya.
Abstract
Pressure drop aliran dua fase memiliki keterkaitan dengan flow pattern yang dipengaruhi oleh beberapa faktor yang diantaranya tegangan permukaan, gravitasi, kecepatan fluida, densitas fluida dan geometri belokan. Geometri belokan 90° memiliki kefleksibilitas dalam merubah arah aliran sehingga umum digunakan dalam suatu instalasi, namun memiliki kelemahan yaitu terjadinya tekanan balik ( pressure drop ) yang besar akibat pengaruh gravitasi yang tegak lurus terhadap bidang vertikal. Tujuan dari penelitian ini adalah untuk mengetahui pressure drop yang terjadi di belokan 90° dari posisi horizontal ke posisi vertikal serta menganalisa flow pattern fluida dua fase (air-udara) di belokan 90° secara simulasi komputasi dan diverifikasi secara visualisasi dengan bantuan kamera digital high speed . Manfaat yang diharapkan dari penelitian ini adalah memberikan informasi pengaruh aliran fluida dua fase (air-udara) dalam pengembangannya di bidang industri seperti perancangan desain yang optimum, prediksi keterbatasan kemampuan operasional mesin, mendiagnosa kegagalan atau kerusakan pada kondisi tertentu, serta keamanan dalam pengoperasian peralatan industri. Penelitian dimulai bulan Juni sampai November 2014 di Studio Perancangan dan Rekayasa Sistem (SPRS) dan Laboratorium Fenomena Dasar Jurusan Teknik Mesin Fakultas Teknik Universitas Brawijaya. Penelitian ini menggunakan bahan pipa PVC Clear (CPVC) dan acrylic (PMMA) pada seksi uji belokan 90° untuk mengamati flow pattern secara visualisasi selanjutnya dianalisa melalui simulasi KDF dengan software ANSYS FLUENT 14.5 dan diverifikasi secara eksperimen. Perhitungan pressure drop di belokan 90 dihitung secara teoritis dan eksperimen sehingga penelitian dapat dikaji secara ilmiah. Hasil penelitian menunjukkan ada hubungan antara flow pattern terhadap besar pressure drop aliran dua fase di belokan 90° dari ketebalan interface . Semakin besar ketebalan interface maka pressure drop semakin menurun baik secara teoritis maupun eksperimen yang dikarenakan interface berkaitan dengan gesekan antar fase yang dalam hal ini adalah efek slip jika bilangan Reynolds air ( Re SL ) menurun maka slip antar fase besar. Efek slip merupakan bagian dari fraksi volume yang mempengaruhi gaya sentrifugal yang mendorong fase air ke dinding luar belokan serta pengaruh elevasi dan tekanan balik di belokan 90° memberikan dampak pada gesekan antar fase dan ketebalan interface . Semakin besar proporsi volumetrik udara ( β ) maka bilangan Reynolds air ( Re SL ) semakin menurun sehingga menyebabkan gesekan antar fase yang besar. Fenomena aliran dua fase di belokan 90° berupa flow pattern slug yang mana fase udara menyentuh bagian atas atau bagian radius dalam belokan 90°. Semakin besar proporsi volumetrik udara ( β ) juga menyebabkan ketidakstabilan fluida air dan mempengaruhi flow pattern di belokan 90°, ketidakstabilan tersebut dikarenakan aliran balik di belokan 90° serta gaya sentrifugal yang disebabkan belokan 90° tersebut memberikan pengaruh terhadap gaya gesek antar fase yang saling menekan dengan munculnya interface dengan ketebalan tertentu.
English Abstract
Two-phase flow of pressure drop associated with any flow pattern that influenced by several factors including surface tension, gravity, fluid velocity, fluid density and geometry of curves. Geometry at 90° has flexibility in changing direction of flow, so it commonly used in an installation, but it has disadvantage of large back pressure (pressure drop) due to influence of perpendicular gravity to vertical surface. purpose of this study were to determine pressure drop that occurs in 90° curves from horizontal position to a vertical position and to analyze flow pattern of two-phase fluid (water-air) at 90° curves in computational simulation and visualization verified with help of high-speed digital camera. benefits of this research is informing of two-phase fluid flow (water-air) in development of industry as optimum design planning, prediction on engine operational capability limitations, diagnose failure or damage in certain conditions, and safety in operational of industrial equipment. study began in June until November 2014 at Studio Design and Engineering Systems and Basic Phenomena Laboratory of Department of Mechanical Engineering, Faculty of Engineering, University of Brawijaya. This study used Clear PVC pipe (CPVC) and acrylic (PMMA) material in 90° curves test section to observe flow pattern visualization n analyzed through simulation modeling with ANSYS FLUENT 14.5 software and verified experimentally. calculation of pressure drop in 90° curve is calculated oretically and experimentally so result of research can be studied scientifically. results showed relationship between flow patterns of amount of pressure drop of two-phase flow in 90° curves to thickness of interface. bigger thickness of interface, pressure drop decreases both oretically and experimentally due to interface of friction interface between phases in this case is effect of slip and its value is decreases to Reynolds number. Slip effect is part of volume fraction which influenced centrifugal force to push water phase to outer wall of curve so that bigger volumetric proportion of air ( β ) n water Reynolds number (Re SL ) will decrease and friction between phase increases, in addition, back pressure in 90°curve also affects thickness of interface. bigger proportion of air volumetric ( β ), water Reynolds number (Re SL ) will decrease, causing large friction between phases, due to bigger friction force pressure drop will decrease. phenomenon of twophase flow in 90° curve in form of slug flow pattern is which phase of air touching top or inner radius of bend 90° curves. bigger volumetric proportion of air ( β ) also cause instability of water fluid and affect flow pattern in 90° curve, instability happened due to back pressure on 90° curve and centrifugal force which caused by 90° curves affect to frictional forces between phases that pressed against each o r with emerge of interface with a certain thickness. smaller water Reynolds number (Re SL ) bigger thickness of interface, thickness of interface also affects decrease of pressure drop.
| Item Type: | Thesis (Magister) |
|---|---|
| Identification Number: | TES/620.106/NUG/s/041500214 |
| Subjects: | 600 Technology (Applied sciences) > 620 Engineering and allied operations > 620.1 Engineering mechanics and materials |
| Divisions: | S2/S3 > Magister Teknik Mesin, Fakultas Teknik |
| Depositing User: | Endro Setyobudi |
| Date Deposited: | 27 Jan 2015 14:03 |
| Last Modified: | 27 Jan 2015 14:03 |
| URI: | http://repository.ub.ac.id/id/eprint/158590 |
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