Studi Eksperimen Karakteristik Aliran Dalam Flat-Walled Diffuser Dengan Dan Tanpa Vortex Generator Pada Bilangan Redh = 3,1 X 105 Dan 6,1 X 105

Haq, Fahmi Khafidhul (2016) Studi Eksperimen Karakteristik Aliran Dalam Flat-Walled Diffuser Dengan Dan Tanpa Vortex Generator Pada Bilangan Redh = 3,1 X 105 Dan 6,1 X 105. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Diffuser merupakan suatu konstruksi ducting yang mengalami pembesaran penampang searah dengan aliran fluida. Penggunaan diffuser yaitu pada wind tunnel, air conditioner sentral, fire extinguisher, heat recovery steam generator (HRSG) dan body mobil. Diffuser dalam dunia otomotif digunakan pada mobil balap Formula One yang berfungsi mengurangi gaya hambat pada mobil tersebut. Karena dengan adanya diffuser di belakang, tekanan aliran di belakang mobil meningkat. Test section yang digunakan pada penelitian ini adalah symmetric flat-walled diffuser dengan area ratio 2,2 yang memiliki sudut divergensi (2θ) = 8°, panjang diffuser, L1, = 1800 mm,panjang upstream channel, L2, = 1200 mm dan panjang downstream channel, L3, = 1000 mm, serta memiliki tinggi inlet diffuser (W1) = 518,7 mm dan tinggi outlet diffuser (W2) = 770,5 mm. Pada penelitian ini digunakan bilangan Reynolds 3,1 x 105 dan 6,1 x 105 berdasarkan diameter hidrolik diffuser dan kecepatan maksimum pada inlet diffuser. Selain peningkatan bilangan Reynolds pada penelitian ini juga digunakan tanpa vortex generator (VG) yang hasilnya dibanding dengan diffuser tanpa VG. Hasil yang didapatkan dari penelitian ini yaitu tidak ada separasi aliran pada diffuser. Peningkatan bilangan Reynolds juga tidak berpengaruh secara signifikan terhadap performa diffuser. Hal tersebut dapat dilihat dari nilai Cpr pada ReDH = 3,1 x 105 dan 6,1 x 105 tanpa VG mengalami penurunan 3,1 % dan nilai Cpr pada ReDH = 3,1 x 105 dan 6,1 x 105 dengan VG mengalami kenaikan 5,7 %. Selain itu penambahan VG justru menurunkan performa diffuser. Hal tersebut dapat dilihat pada ReDH = 3,1 x 105 mengalami penurunan Cpr sebesar 12,1 % dan pada ReDH = 6,1 x 105 mengalami penurunan Cpr sebesar 4,1 % dengan penambahan VG. Sedangkan untuk intensitas turbulensi (IT) pada downstream diffuser ketika ditambahkan VG mengalami penurunan. Hal tersebut dapat dilihat dari nilai IT pada ReDH = 3,1 x 105 mengalami penurunan sebesar 26,4 % dan pada ReDH = 6,1 x 105 mengalami penurunan sebesar 2,7 % dengan penambahan VG. ================================================================================================================== Diffuser is a construction of ducting which has an enlargement in cross-sectional flow direction. The use of a diffuser includes in a wind tunnel, central ac, fire extinguisher, heat recovery steam generator (HRSG), and the body of a car. Diffuser in the automotive world is used in Formula One racing car which functions is to reduce drag on the car. With the diffuser in the back, the flow pressure in the back of the car increases. The test section that used in this experiment is a symmetric flat-walled diffuser with area ratio 2,2 which has a divergency angle (2θ) = 8°, diffuser length, L1 = 1800 mm, length upstream channel, L2 = 1200 mm and a length downstream channel, L3, = 1000 mm, and height of diffuser inlet (W1) = 518,7 mm and height of the diffuser outlet (W2) = 770.5 mm. This experiment uses the Reynolds number of 3,1 x 105 and 6,1 x 105 based on hydraulic diameter of diffuser and the maximum flow speed at of diffuser inlet. In addition to the use of two different Reynolds number, this experiment also uses without vortex generator (VG) where the results are compared with diffuser without VG. The results obtained from this experiment knows there is no flow separation in the diffuser. The increase of Reynolds number does not affect significantly to the performance of diffuser. It can be seen from the Cpr on ReDH = 3,1 x 105 and 6,1 x 105 without VG decreases 3,1 % and the value of Cpr on ReDH = 3,1 x 105 and 6,1 x 105 with VG increases 5,7%. The addition of VG reduces the performance of diffuser. It can be seen at ReDH = 3,1 x 105, Cpr decreased by 12,1 % and in ReDH = 6,1 x 105, Cpr decreases by 4,1 % with the addtion of VG. As for the turbulence intensity (TI) at downstream diffuser is reduced with addition of VG. It can be seen from the value of TI at ReDH = 3,1 x 105 decreases by 26,4 % and on ReDH = 6,1 x 105 decreases by 2,7 % with the addition of VG.

Item Type: Thesis (Undergraduate)
Additional Information: RSM 620.106 4 Haq s
Uncontrolled Keywords: symmetric flat-walled diffuser, aspect ratio konstan, pressure coefficient, tegangan geser dinding, sudut divergensi.
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User: Users 13 not found.
Date Deposited: 21 Jun 2017 07:10
Last Modified: 26 Dec 2018 08:42
URI: http://repository.its.ac.id/id/eprint/41804

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