Studi Eksperimen Karakteristik Aliran Fluida Melalui Large Octagonal Elbow Pada Closed-Loop Subsonic Wind Tunnel

Faizin, Ahmad Khairul (2017) Studi Eksperimen Karakteristik Aliran Fluida Melalui Large Octagonal Elbow Pada Closed-Loop Subsonic Wind Tunnel. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penggunaan elbow pada instalasi closed-loop wind tunnel akan menyebabkan terjadinya kerugian tekanan pada aliran, besarnya pressure drop pada aliran yang melalui elbow tersebut dipengaruhi oleh besarnya jari-jari kelengkungan, friction dan sudut belok dari elbow. Hal ini menyebabkan terjadinya separasi dan secondary flow pada elbow dan menyebabkan kerugian energi aliran (headloss) yang lebih besar. Test section yang digunakan di dalam studi ini berupa dua large octagonal elbow 90º dengan radius ratio (rm/Dh) = 0.6. Diamater hydraulic elbow sebesar 806 mm. Pada penelitian ini digunakan bilangan Reynolds ReDh = 2,57 x 105 dan 4,63 x 105 berdasarkan inlet freestream velocity (U∞). Hasil eksprimen menunjukkan nilai ΔCp pada Re = 2,57 x 105 di elbow 1 sebesar 0,683 dan elbow 2 sebesar 1,055. Besarnya perbedaan tekanan outer dan inner wall berpotensi terjadinya aliran sekunder. Pada xi/Dh = 1.35, aliran fluida mengalami percepatan pada sisi inner dan aliran fluida mengalami perlambatan sisi outer. Antara xi/Dh = 1.63 sampai xi/Dh = 2.01 terjadi pergeseran kecepatan maksimum dari sisi inner ke sisi outer. Intensitas turbulensi pada outlet octagonal elbow 2 (xi/Dh = 2.54) dan Re = 4,63 x 105 sebesar 1,83 %, profil intensitas turbulensi di pusat profil [(r-ri)/b = 0,5] sebesar 1,8 % dan berkisar 4 % di daerah inner dan outer wall. Rendahnya nilai intensitas turbulensi ini karena pengaruh dari instalasi honeycomb. ================================================================== The use of elbow in closed-loop wind tunnel installation will cause pressure loss at flow, the amount of pressure drop in flow through the elbow is influenced by the magnitude of the radius of curvature, friction and the angle of the elbow. This leads to separation and secondary flow in the elbow and leads to greater loss of energy flow (headloss). The test section used in this study was two large octagonal elbow 90º with radius ratio (rm/Dh) = 0.6. Diamater hydraulic elbow of 806 mm. In this study used Reynolds ReDh = 2.57 x 105 and 4.63 x 105 based on freestream velocity (U∞) inlet. The experimental results show the value of ΔCp at Re = 2.57 x 105 in elbow 1 of 0.683 and elbow 2 of 1.055. The magnitude of the difference in outer and inner wall pressures has the potential for secondary flow. At xi / Dh = 1.35, the fluid flow accelerates on the inner side and the fluid flow decelerates the outer side. Between xi / Dh = 1.63 to xi / Dh = 2.01 there is a maximum velocity shift from the inner side to the outer side.The intensity of turbulence at outlet octagonal elbow 2 (xi / Dh = 2.54) and Re = 4.63 x 105 of 1.83%, turbulence intensity profile at center of profile [(r-ri) / b = 0,5] of 1,8% and around 4% in inner and outer wall areas. The low value of this turbulence intensity is due to the influence of the honeycomb installation.

Item Type: Thesis (Undergraduate)
Additional Information: RSM 620.106 4 Fai s
Uncontrolled Keywords: Large octagonal elbow 90º, pressure drop, secondary flow, head loss
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction
Divisions: Faculty of Industrial Technology > Mechanical Engineering > (S1) Undergraduate Theses
Depositing User: Ahmad Khairul Faizin
Date Deposited: 03 Oct 2017 02:01
Last Modified: 06 Mar 2019 06:23
URI: http://repository.its.ac.id/id/eprint/46762

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