Studi Eksperimen Karakteristik Aliran Melalui Small Octagonal Elbow 90 Pada Closed-Loop Subsonic Wind Tunnel

Trisetya, Anandhika (2018) Studi Eksperimen Karakteristik Aliran Melalui Small Octagonal Elbow 90 Pada Closed-Loop Subsonic Wind Tunnel. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pada windtunnel tipe saluran tertutup (closed-loop) terdapat elbow yang berfungsi untuk menghubungkan dua saluran lurus yang saling tegak lurus. Adanya elbow pada closed-loop windtunnel menyebabkan terjadinya kerugian tekanan pada aliran fluida. Perubahan arah aliran akibat sudut belokan pada elbow memberikan pengaruh yang besar terhadap pressure drop. Untuk mengetahui karakteristik aliran pada octagonal elbow 90° maka dilakukan penelitian secara eksperimen. Model uji yang digunakan di dalam studi ini berupa small octagonal elbow 90º dengan radius ratio (rm/Dh) = 0.66. Instalasi elbow pertama didahului rumah fan di sisi upstream dan elbow kedua diawali straight duct sebagai upstream flow. Pada penelitian ini digunakan bilangan Reynolds ReDh = 2,08 x 105 dan 4,5 x 105. Hasil yang didapatkan dari penelitian ini berupa nilai ΔCp elbow 1 pada Re = 2.08 x 105 sebesar 1.50 dan pada Re = 4.50 x 105 sebesar 1.50. Pada elbow 2, Re = 2.08 x 105 sebesar 1.60 dan pada Re = 4.50 x 105 sebesar 1.75. Perbedaan nilai Cp antara inner dan outer elbow menyebabkan terjadinya secondary flow. Profil kecepatan pada bidang horizontal menunjukkan terdapat backflow yang disebabkan adanya perbedaan tekanan pada sisi outer dan inner yang besar. Profil kecepatan pada bidang vertikal terdapat daerah kecepatan rendah pada sisi centerline. Intensitas turbulensi pada kedua outlet elbow saat Re = 4.5 x 105 (11.30% dan 4.86%) lebih kecil daripada saat Re = 2.08 x 105 (15.91% dan 7.36%) karena saat bilangan Reynolds tinggi, kecepatan rata-rata dari aliran juga meningkat. Profil intensitas turbulensi pada outlet elbow 1 di pusat profil z/a = 0.5 sebesar 11.40% untuk bidang vertikal, untuk posisi z/a < 0.1 berada pada sekitar 12.30% dan untuk z/a > 0.9 berada pada sekitar 14.40%. =================================================================================================================================================================== In a closed-loop windtunnel there is an elbow that serves to connect two straight lines perpendicular to each other. The presence of elbows on the closed-loop windtunnel causes a pressure loss on the fluid flow. Changes in direction of flow due to angle of turn in elbow give a big influence to pressure drop. To know the flow characteristic at octagonal elbow 90 ° then conducted experimental research. The test model used in this study is small octagonal elbow 90º with radius ratio (rm / Dh) = 0.66. The first elbow installation is preceded by a fan house on the upstream side and the second elbow begins straight duct as an upstream flow. In this study used Reynolds ReDh = 2.08 x 105 and 4.5 x 105. The result of this research is the value of ΔCp elbow 1 at Re = 2.08 x 105 of 1.50 and at Re = 4.5 x 105 of 1.50. In elbow 2, Re = 2.08 x 105 is 1.60 and at Re = 4.5 x 105 of 1.75. Differences in Cp value between inner and outer elbow cause secondary flow. The velocity profile in the horizontal plane indicates a backflow caused by a pressure difference on the outer and inner sides. The velocity profile in the vertical plane has a low velocity area on the centerline side due to the influence of the fan's hub. The intensity of turbulence at both elbow outlets at Re = 4.5 x 105 (11.30% and 4.86%) is smaller than at Re = 2.08 x 105 (15.91% and 7.36%) because when Reynolds numbers are high, the average velocity of the flow also increases. The turbulence intensity profile in outlet elbow 1 at the center of the profile z / a = 0.5 is 11.40% for the vertical plane, for z / a <0.1 positions at about 12.30% and for z / a> 0.9 at about 14.40%.

Item Type: Thesis (Undergraduate)
Additional Information: RSM 620.106 4 Tri s-1 3100018075222
Uncontrolled Keywords: Karakteristik aliran, pressure drop, profil kecepatan, secondary flow, small octagonal elbow 90º.
Subjects: T Technology > TJ Mechanical engineering and machinery
T Technology > TJ Mechanical engineering and machinery > TJ935 Pipe--Fluid dynamics.
Divisions: Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User: Anandhika Trisetya
Date Deposited: 15 Apr 2020 09:01
Last Modified: 15 Apr 2020 09:01
URI: http://repository.its.ac.id/id/eprint/50868

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