Studi Numerik Pengaruh Area Ratio Dan Bilangan Reynolds Terhadap Karakteristik Aliran Turbulen Pada Pipa Sudden Expansion Dengan Chamfered Edge

Amylia, Jasmine Carissa (2026) Studi Numerik Pengaruh Area Ratio Dan Bilangan Reynolds Terhadap Karakteristik Aliran Turbulen Pada Pipa Sudden Expansion Dengan Chamfered Edge. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

**Bahasa Indonesia (rapi tanpa alenia baru):**

Komponen *sudden expansion* pada sistem perpipaan industri sering memicu separasi aliran dan terbentuknya zona resirkulasi, yang mengakibatkan tingginya *pressure drop* dan penurunan efisiensi energi. Modifikasi geometri berupa *chamfered edge* telah terbukti mampu memitigasi separasi tersebut, namun kajian mengenai interaksinya dengan variasi dimensi ekspansi dan kecepatan aliran masih terbatas. Oleh karena itu, penelitian ini bertujuan menginvestigasi pengaruh interaksi antara modifikasi *chamfered edge*, *area ratio*, dan bilangan Reynolds terhadap kerugian energi serta karakteristik aliran turbulen pada pipa *sudden expansion*. Penelitian ini menggunakan simulasi numerik tiga dimensi berbasis *Computational Fluid Dynamics* (CFD) dengan perangkat lunak ANSYS 2023 R2. Pemodelan menerapkan model turbulensi Realizable k-ε dan *enhanced wall treatment*. Simulasi dilakukan menggunakan fluida air pada bilangan Reynolds 1,5 × 10⁵ dan 3 × 10⁵, dengan variasi *area ratio* sebesar 2, 3, dan 4. Geometri *chamfer* ditetapkan pada sudut 20° dengan panjang tak berdimensi Ld/D₁ = 0,2. Hasil penelitian dianalisis berdasarkan nilai koefisien kerugian lokal (KL), distribusi *pressure coefficient*, distribusi kecepatan, serta data kualitatif berupa kontur tekanan statis, pola *streamline*, dan profil kecepatan. Hasil penelitian menunjukkan bahwa penggunaan *chamfered edge* mampu menurunkan nilai KL dibandingkan *sudden expansion* konvensional tanpa *chamfer*. Pada Re = 3 × 10⁵, nilai KL menurun sebesar 44,29% untuk AR = 2, sebesar 34,58% untuk AR = 3, dan sebesar 25,23% untuk AR = 4. Selain itu, peningkatan *area ratio* menyebabkan nilai KL semakin besar karena zona separasi dan resirkulasi yang terbentuk semakin luas. Pada konfigurasi dengan *chamfer* dan Re = 3 × 10⁵, nilai KL meningkat dari 0,1409 pada AR = 2 menjadi 0,2972 pada AR = 3 dan 0,3966 pada AR = 4. Sementara itu, pengaruh bilangan Reynolds terhadap nilai KL relatif kecil, yaitu hanya sebesar 0,50% pada AR = 2, 0,92% pada AR = 3, dan 0,74% pada AR = 4. Dengan demikian, pada rentang bilangan Reynolds yang dikaji, nilai KL menunjukkan kecenderungan *Reynolds-number independence*, sehingga kerugian lokal lebih dominan dipengaruhi oleh geometri ekspansi, khususnya *area ratio* dan keberadaan *chamfered edge*.
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The sudden expansion component in industrial piping systems frequently triggers flow separation and recirculation zones, resulting in high pressure drops and reduced energy efficiency. Geometric modification in the form of a *chamfered edge* has been shown to mitigate flow separation; however, studies investigating its interaction with variations in expansion geometry and flow velocity remain limited. Therefore, this study aims to investigate the interaction effects of *chamfered edge* modification, area ratio, and Reynolds number on energy losses and turbulent flow characteristics in sudden expansion pipes. This research employs three-dimensional numerical simulations based on *Computational Fluid Dynamics* (CFD) using ANSYS 2023 R2 software. The simulations apply the Realizable k-ε turbulence model with *enhanced wall treatment*. Water is used as the working fluid at Reynolds numbers of 1.5 × 10⁵ and 3 × 10⁵, with area ratio variations of 2, 3, and 4. The chamfer geometry is defined by a 20° angle and a dimensionless length of Ld/D₁ = 0.2. The results are analyzed using the local loss coefficient (KL), pressure coefficient distribution, velocity distribution, and qualitative observations, including static pressure contours, streamline patterns, and velocity profiles. The results demonstrate that the chamfered edge reduces the KL value compared with the conventional sudden expansion without a chamfer. At Re = 3 × 10⁵, the KL value decreases by 44.29% for AR = 2, 34.58% for AR = 3, and 25.23% for AR = 4. In addition, increasing the area ratio results in higher KL values because the flow separation and recirculation zones become larger. For the chamfered configuration at Re = 3 × 10⁵, the KL value increases from 0.1409 at AR = 2 to 0.2972 at AR = 3 and 0.3966 at AR = 4. Meanwhile, the effect of Reynolds number on KL is relatively small, with changes of only 0.50% for AR = 2, 0.92% for AR = 3, and 0.74% for AR = 4. Therefore, within the investigated Reynolds number range, the KL value exhibits Reynolds-number independence, indicating that local losses are predominantly governed by the expansion geometry, particularly the area ratio and the presence of the chamfered edge.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Area ratio, Chamfered Edge, Pressure Drop, Reynolds Number, Sudden expansion.
Subjects:	T Technology > T Technology (General) > T57.62 Simulation T Technology > TJ Mechanical engineering and machinery > TJ935 Pipe--Fluid dynamics. Tubes--Fluid dynamics
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Jasmine Carissa Amylia
Date Deposited:	01 Aug 2026 04:06
Last Modified:	01 Aug 2026 04:06
URI:	http://repository.its.ac.id/id/eprint/140901

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