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EFFECT OF BASE CAVITIES ON THE DRAG AND WAKE OF A TWO-DIMENSIONAL BLUFF BODY

Chandrmohan, Aravind (Abdurrahmaan) (2009) EFFECT OF BASE CAVITIES ON THE DRAG AND WAKE OF A TWO-DIMENSIONAL BLUFF BODY. Masters thesis, King Fahd University of Petroleum and Minerals.

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Arabic Abstract

ىسجن ءا..نا تي.اقي .ه. تفهخخي ثاف..جح ش.ثأخن تساسد تناسشنا ِزْ وذقحتطقاس ت.فهخ .ر دا.بلأا .ئاُث ت..اض.ب تيذقي. عافحسلاإ .نإ ل.طنا تبسُب مكشنا1:8 . ءاشجإ ىح.، ىسجنا ت.ا.َ .ف تخبثًنا ثاف..جخنا ٍي لاكشأ. لا.طأ ةذ. تبشجح ىح ..اس. صذن.َس ىقس ذُ. ٌدا.ًنا. ل.شخبهن ذ.ف كهًنا ت.ياجب ءاضفنا. ٌاش.طنا تسذُْ ىسقن غباخنا ءا..نا قفَ .ف تبشجخنا6‚2×410 . ت.ُقح واذخخسا .نا تفاضلااب ءا..نا تي.اقي ة.ق طا.ق. ، تخباث ش.غنا. تخباثنا ظغضنا ثاسا.ق زخا ىح ذقنتخبثًنا ثاف..جخنا. ىسجنا فهخ ءا..نا تكشح تساسذن ثاً.سجنا ت.شسن .فاشغ.ح.فنا ش..صخنا . ثاسا.ق ثش.ظأ ذقن ٍي ةدا.ضنا جَاك ث.ح تفهخخي بسُب ٍكن. ف..اجخنا غي ذ.ض. ظغضنا ٌأ شقخسًنا ظغضنا-0.58 .نإ ف..جح ٌ.ذب ىسجهن -0.52 ف..جخهن 1/6 ،أ -0.31 ف..جخهن 1/3 ،أ -0.42 ف..جخهن 2/3 . أ -0.46 ٌأ ث.ح مئاًنا ف..جخهن (أ) مثًح ف..جخنا ققح ذقف تي.اقًنا ة.قنا ثاسا.قن تبسُناب ايأ ،ىسجنا عافحسإ1/3 ميا.ًب ءا..هن تي.اقي مقأ أ0.35 تَساقي اب.شقح ..اس. تي.اقي ميا.ي ّن .زنا. ثاف..جح ٌ.ذب ىسجنا غي0.58 ا.خي.اقي ثلايا.ي جَاك ذقف .شخلأا ثاف..جخهن تبسُناب. ، .ناخناك :0.42 ف..جخهن 2/3 ،أ0.43 ،مئاًنا ف..جخهن 0.52 ف..جخهن 1/6 . أ0.54 ٌأ ٍ.ح .ف ،قهغًنا ف..جخهن ذُ. ثاددشح د.ج. جخبثأ ِشقخسي ش.غنا ظغضنا ثاسا.ق11 مْ.شخس ىقس ..اسحضحشْ 0.07 غي ش.غخح لا ثاددشخنا ِزْ ، ٍ.خقطُي د.ج. ثش.ظأ ذقف ثاف..جخنا . ىسجنا فهخ ءا..نا تكشح جئاخَ ايأ ،ذ.ضح ا.خقاط ٍكن. تفهخخًنا ثاف..جخنا ج.بثحثاف..جخنا لاكشأ ش.غح غي اش.ثك ش.غخ. لا ا.ن.ط ٌأ . ىسجنا فهخ ءا..نا ٌاس.ذن .

English Abstract

In the present investigation, we tested the effects of various cavities on the base drag and wake of a two-dimensional bluff body. The bluff body model has a blunt base and an elliptical leading edge of semimajor to semiminor axis ratio of 8:1. Different lengths and shapes of cavities were attached to the blunt base of the bluff body. Experiments were conducted in the 1×1 m2 wind tunnel of the Department of Aerospace Engineering at KFUPM at a Reynolds number ( Reh ) of 2.6x104. Steady and unsteady base pressure measurements, force measurements as well as Particle Image Velocimetry (PIV) measurements were conducted to study the flow properties. The steady base pressure measurements show that base pressure increases with the attachment of the cavities. The increase was from -0.58 for the base model to -0.52 with 1/6 h cavity, -0.31 with 1/3 h cavity, -0.42 for 2/3 h cavity and -0.46 for angled cavity. The drag-force measurements show that the highest drag reduction is obtained by using 1/3 h cavity ( Cd ~ 0.35 ) compared to the base model ( Cd ~ 0.58 ) followed by 2/3 h cavity ( Cd ~ 0.43 ), angled cavity ( Cd ~ 0.48 ), 1/6 h cavity ( Cd ~ 0.52 ) and closed-C cavity ( Cd ~ 0.54 ). The unsteady base pressure measurements show a dominating peak at a frequency of 11 Hz corresponding to a Strouhal number of 0.07. The frequency of this peak was not altered by cavities, but the energy of the peak increased. The mean velocity fields obtained by using PIV show two recirculation regions behind the base model and cavities. The lengths of the recirculation region were not altered much with the attachment of the cavities.



Item Type:Thesis (Masters)
Date:31 April 2009
Date Type:Completion
Subjects:Aerospace
Divisions:College Of Engineering Sciences > Aerospace Engineering Dept
Creators:Chandrmohan, Aravind (Abdurrahmaan)
Email:abdlrhmn@kfupm.edu.sa
Committee Advisor:Al-Garni, Abdullah M.
Committee Co-Advisor:Al-Garni, Ahmed Z.
Committee Members:kassem, Ayman H. and Abdelrahman, Wael G. and El-Shaarawi, Maged A.I.
ID Code:136114
Deposited By:ARAVIND CHANDRAMOHAN ABDULRAHMAN
Deposited On:01 Aug 2009 08:53
Last Modified:30 Apr 2011 17:00

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