Kurniawan, Dinaryuda Dwi (2015) Studi Numerik Karakteristik Aliran Fluida Di Dalam Symmetric Flat-Walled Diffuser Dengan Variasi Intensitas Turbulensi Pada Inlet Section. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Diffuser merupakan salah satu konstruksi yang biasa digunakan didalam sistem aliran fluida. Performa diffuser dapat ditunjukkan dengan nilai koefisen tekanan (Cp) fluida yang mengalir di dalamnya. Adverse pressure gradient (APG) di dalam diffuser dapat menyebabkan boundary layer berkembang dengan cepat sehingga dapat mengakibatkan separasi aliran dan Cp menjadi rendah. Untuk menunda separasi perlu dilakukan penelitian lebih lanjut tentang diffuser dengan modifikasi nilai intensitas turbulensi pada sisi inlet untuk memperbaiki nilai koefisen tekanan (Cp) diffuser. Penelitian ini bertujuan untuk mengevaluasi karakteristik aliran fluida pada symmetric flat-walled diffuser dengan aspect ratio konstan dengan sudut divergensi (2θ) = 8°. Pada penelitian ini digunakan bilangan Reynolds 1.55 x 105 dan 6.2 x 105 berdasarkan tinggi dan kecepatan inlet diffuser. Test section penelitian terdiri dari 3 bagian yaitu symmetric diffuser, upstream channel, dan downstream channel. Symmetric diffuser memiliki panjang (L1) = 1500 mm, upstream channel memiliki panjang (L2) = 600 mm, dan downstream channel memiliki panjang (L3) = 1000 mm. Test section secara keseluruhan memiliki lebar inlet span (b1) = 300 mm, lebar outlet span (b2) = 518.8 mm dan tinggi inlet diffuser (W1) = 300 mm, tinggi outlet diffuser (W2) = 518.8 mm. Penelitian ini menggunakan metode numerik dengan software Fluent 6.3.26 dengan turbulence model k-ω shear stress transport (SST). iv Hasil yang diperoleh dari penelitian menunjukkan bahwa tidak terjadi separasi aliran pada bidang midspan vertikal maupun horizontal pada intensitas turbulensi Tu = 1% maupun Tu = 10%. Namun berdasarkan visualisasi vektor kecepatan, separasi aliran dapat diamati pada bidang midspan horizontal pada z/W1 = 11/12 dan z/W1 = 1. Separasi ditunjukkan pada daerah setelah inlet diffuser, yaitu untuk z/W1 = 11/12 pada x/L1 = 0.4 hingga x/L1 = 37/30 (x = 1.85 m), sedangkan untuk z/W1 = 1 ditunjukkan terjadinya separasi pada daerah sesaat setelah inlet diffuser, yaitu pada x/L1 = 0.4 hingga x/L1 = 47/30 (x = 2.35m) pada ReW1 = 1.55 x 105 dan ReW1 = 6.2 x 105 . Peningkatan bilangan Reynolds tidak menunjukkan terjadinya penundaan separasi diakibatkan pengaruh adverse pressure gradient yang besar.
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Diffuser is one of the construction that is able to control the behavior of the fluid. Performance of diffuser can be indicated by the value of the pressure coefficient (Cp) fluid that flowing in it. Adverse pressure gradient (APG) causes boundary layer develops rapidly so that it causes separation and Cp becomes low. So that need to evaluating divergence angle of diffuser to delay the separation to get optimization Cp of diffuser. This study aimed to evaluate the characteristics of fluid flow in a symmetric flat-walled diffuser with a constant aspect ratio with two divergence angle (2θ) = 8 °. In this study used the Reynolds number 1.55 x 105 and 6.2 x 105 based on the height and speed of the inlet diffuser. Test section consisted of three parts, namely symmetric diffuser, upstream channels, and downstream channels. The symmetric diffuser has a length (L1) = 1500 mm, the upstream channel length (L2) = 600 mm, and the downstream channel has a length (L3) = 1000 mm. Overall test section inlet width span (b1) = 300 mm, the width of the outlet span (b2) = 518.8 mm and height of the inlet diffuser (W1) = 300 mm, height outlet diffuser (W2) = 518.8 mm. This study uses a numerical method with software Fluent 6.3.26 with k-ω turbulence model of shear stress transport (SST). vi The results of the study showed that there is no flow separation on the field at midspan vertical and horizontal in turbulence intensity Tu = 1% and Tu = 10%. However, based on the velocity vector visualization, flow separation can be observed at midspan plane horizontal at z/W1 = 11/12 dan z/W1 = 1. The occurrence of separation indicated in the area after the inlet diffuser, ie for z/W1 = 11/12 at x / L1 = 0.4 until x / L1 = 37/30 (x = 1.85 m), while for z/W1 = 1 is shown the occurrence of separation in the area shortly after the inlet diffuser, are at x / L1 = 0.4 until x / L1 = 47/30 (x = 2.35 m) at ReW1 = 1.55 x 105 and ReW1 = 6.2 x 105 . Increasing of the Reynolds number did not show a separation delay caused by adverse pressure gradient effect.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | adverse pressure gradient, aspect ratio, symmetric flat-walled diffuser, turbulence intensity |
| Subjects: | T Technology > TJ Mechanical engineering and machinery > TJ935 Pipe--Fluid dynamics. Tubes--Fluid dynamics |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | - Davi Wah |
| Date Deposited: | 28 Feb 2023 08:31 |
| Last Modified: | 28 Feb 2023 08:31 |
| URI: | http://repository.its.ac.id/id/eprint/96106 |
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