Yhasmin, Salma (2015) Studi Eksperimen Tentang Karakteristik Aliran Pada Silinder Sirkular Yang Diganggu Oleh Prisma Segitiga Samasisi, Prisma Segiempat Samasisi, Dan Silinder Sirkular (Studi Kasus Untuk Variasi Jarak [S/D] = 0,9-1,15). Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Masalah dibidang aerodinamika dari beberapa struktur
medan aliran telah sering mendapat perhatian dari para engineer
dan investigatior lainnya selama beberapa dekade . Berbagai
penelitian yang berbeda menunjukkan bahwa konfigurasi aliran
ini memiliki banyak aplikasi dibidang teknik dan masih ada
contoh permasalahan salah satunya adalah tantangan dalam
mekanika fluida, seperti riser lepas pantai, dermaga jembatan,
menara, tiang, dll. Oleh karena itu, pentingnya untuk melanjutkan
penelitian pada silinder sirkular sebagai obyek, terutama pada
konfigurasi kelompok. Penelitian ini adalah untuk memberikan
informasi bagaimana suatu aliran mengurangi gaya aerodinamis
pada silinder sirkular dengan melakukan pengontrolan secara
pasif , seperti prisma segi empat diputar 0º ( Tipe A ) , prisma
empat persegi panjang diputar 45º (Tipe B ) , segitiga prisma
diputar 30º (Tipe C ) , prisma segitiga diputar 210º (Tipe D ) ,
dan silinder sirkuler (Tipe E ) .
Penelitian ini dilakukan secara eksperimen pada sebuah
wind tunnel jenis subsonic open circuit dengan benda uji berupa
seilinder utama dengan diameter 60 mm dan 7,5 mm pada body
pengganggu tipe A, tipe B, tipe C, tipe D, dan tipe E dengan
variasi jarak S/D = 0,90, 0,95, 1,00, 1,05, 1,10 dan 1,15.
Pengujian ini dilakukan pada wind tunnel berjenis subsonic open
circuit wind tunnel dengan panjang 1780 mm dan ukuran pada
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test section wind tunnel 660 mm x 660 mm. Kecepatan freestream
pada wind tunnel diambil konstan pada 13,88 m/s pada saat
dilakukan pengambilan data dengan Reynolds Number 5,3 x 104.
Pengukuran distribusi tekanan menggunakan 72 buah
titik pada wall pressure tap dengan jarak 5º tiap sudut yang
dipasang disekeliling silinder utama, pengukuran profil
kecepatan menggunakan pitot static tube pada jarak pengukuran
x/D= 3 kemudian pengambilan data untuk perhitungan bilangan
Strouhal dilakukan dengan menempatkan probe HWA pada jarak
x = 3D dan y = 1D .
Pada penelitian ini, dapat mengetahui gaya drag yang
dihasilkan pada silinder utama dengan diberi pengganggu
sebagai pengontrol pasif. Hal ini mengindikasikan bahwa silinder
Tipe B pada jarak S/D 1,15 paling efektif dalam menurunkan
gaya drag dibelakang silinder utama, penurunan sebesar 0,27
kali pada silinder tanpa pengganggu. ============= The aerodynamic problem of multiple structures in a flow
field have frequently received the attention of engineer and other
investigatiors for saveral decades. Different studies show that this
flow configuration has many engineering application and still
present one of the challenges in fluid mechanics, such as offshore
riser, bridge piers, towers, mast and stays, etc. Therefore, it is
still important to continue the study with circular cylinder as an
object, especially on a group configuration. This study is to
present the reducing of aerodynamics forces on a circular
cylinder by upstream installation of some bluff bodies as passive
control or disturbance, such as rectangular prism is rotated 0º
(Type A), rectangular prism is rotated 45º (Type B), triangular
prism is rotated 30º (Type C), triangular prism is rotated 210º
(Type D), and circular cylinder (Type E).
In order to reduce the drag force on a circular cylinder
(D= 60 mm), five bluff body; type A, B, C, D, and E having a
diameter (d) or long side of 7.5 mm were used as a passive
control. The passive control were located in various spacing
position of S/D = 0.9, 0.95, 1.0, 1.05, 1.1, and 1.15. The
experiment were carried out in a subsonic open circuit wind
tunnel. This facility has a 1780 mm long, with test section 660 mm
x 660 mm. The free same velocity of wind tunnel could be
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adjusted constant to 13.88 m/s, corresponding to Reynolds
number Re = 5.3 x 104 (based on diameter D and the free stream
velocity). Seventy-two pressure taps with interval 5º were
installed on the wall of the circular cylinder and connected to an
inclined kerosene manometer, which it makes it possible to
measure the pressure distribution around the circular cylinder.
The velocity profile behind the circular cylinder was measured
using a pitot-static tube connected to inclined manometer. The
pitot-static tube was placed at 18 cm at the rear of the axis of the
cylinder or correspondin to x/d = 3, and finally frequencyof
vortex shedding behind the cylinder was measured at x/D = 3 and
y/D = 1 by hot wire anemometer.
The experiment result show that there is reduction of
drag coefficient on main cylinder by upstream installation of the
some bluff body as passive control or cylinder disturbance. The
passive control “type B” at S/D 1.15 gives the highest darg
reduction on the larger circular cylinder situated downstream. It
gives about 0.27 times the drag of a single cylinder.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Additional Information: | RSM 620.106 4 Yha s 3100015062073 |
| Uncontrolled Keywords: | pasif kontrol, drag, prisma segitiga sama sisi, prisma segi empat sama sisi, dan silinder sirkular, passive control, drag, equilateral triangular prism, rectangular prism, and circular cylinder |
| Subjects: | Q Science > QA Mathematics > QA911 Fluid dynamics. Hydrodynamics |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | - Davi Wah |
| Date Deposited: | 05 Dec 2019 05:01 |
| Last Modified: | 05 Dec 2019 05:01 |
| URI: | http://repository.its.ac.id/id/eprint/72158 |
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