Passive control of flow structures around a circular cylinder by using screen

Oruç, Vedat

doi:10.1016/j.jfluidstructs.2012.05.002

Cited by 52 publications

(22 citation statements)

References 33 publications

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“…The following ideas have been previously tested: grooves, [3][4][5] bumps and dimples, [6][7][8] and screens, [9,10] among others. These studies showed that surface manipulation can effectively delay the separation point.…”

Section: Discussionmentioning

confidence: 99%

Surface pressure distribution on patterned cylinders under simulated atmospheric boundary layer winds

Ferreira

Amirinia

Jung

2017

Structural Design Tall Build

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SummaryExtensive research has been previously conducted on pressure distribution of cylindrical models under uniform and laminar flow conditions. However, typical civil structures such as high-rise buildings or towers are under the atmospheric boundary layer (ABL) conditions. Knowing this, the present research aims to quantify the effectiveness of surface patterns in reducing the suction zone under a simulated ABL condition. Two different surface patterns, U-grooved and V-grooved, were selected to be tested in wind tunnel. In addition to patterned cylinders, tests were also conducted on a smooth-surfaced cylinder, serving as the control of the experiment. An array of roughness elements was placed at the upstream end of the test section with the purpose of inducing ABL winds within the test section. Without the ABL wind, the cylinder covered in V-grooved riblets was most effective in reducing the suction zone followed by the U-grooved cylinder. With the simulated ABL condition, V-grooved cylinder continued to show decreased suction although the amount of decrease was less. Both grooved cylinders showed decreased peak pressure coefficients under the ABL condition compared to the non-ABL condition.KEYWORDS atmospheric boundary layer, cylinder, flow separation, pressure coefficient, surface pattern, wind tunnel 1 | INTRODUCTION High-rise buildings, categorized as any structure requiring the use of a mechanical vertical transportation system (i.e., elevators), can vary greatly in size, from a common 10-story office building to the 828-m-tall Burj Khalifa in Dubai. Although each structure faces its own design challenges, wind is a major determining factor in high-rise buildings.As wind strikes a structure, flow may remain attached or be separated from the surface of the structure. The windward side experiences a positive pressure whereas the leeward side experiences a negative pressure, often referred to as suction. [1] Flow separation typically causes an increase in pressure drag that is the form of drag caused by the pressure differences between the front (windward) and rear (leeward) surface of a structure. By delaying the separation point (occurring at a leeward point), pressure drag can be reduced.All experiments related to delaying the flow separation can be grouped into 2 major categories, passive or active. A passive mechanism is one that is related to the building architecture, where features are intentionally incorporated into a design in order to dictate fluid flow around a particular surface. Oppositely, an active mechanism requires that external energy be added into a particular system. [2] The current paper will deal strictly with passive mechanisms.The majority of techniques researched with cylindrical structures involves surface manipulation, such as added roughness or patterns. The following ideas have been previously tested: grooves, [3][4][5] bumps and dimples, [6][7][8] and screens, [9,10] among others. These studies showed that surface manipulation can effectively delay the separation point. Delay...

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Section: Discussionmentioning

confidence: 99%

Surface pressure distribution on patterned cylinders under simulated atmospheric boundary layer winds

Ferreira

Amirinia

Jung

2017

Structural Design Tall Build

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“…While research has been conducted on the fluid flow through a single object, i.e., fluid flow through more than one object with various shapes, sizes and configurations, other research has been done on fluid flow through a circular cylinder with a tandem configuration [4][5][6][7], a circular cylinder enclosed by a screen [8] and an elliptical cylinder with a side-by-side configuration [9]. The use of more than one object means that one object acts as the main object and the others act as passive controls.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling of Drag Coefficient Reduction in Circular Cylinder Using Two Passive Controls at Re = 1000

Imron

Mardianto

Widodo

et al. 2018

MCA

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Abstract:One of the many ways to reduce drag force is by adding a small object called passive control. Two passive controls will be placed in front and at the rear of the main object. The main object used is a circular cylinder, and the passive controls used are the Type-I cylinder in the front and an elliptical cylinder at the rear of the main object. The distances between the main object and the passive controls are varied. The Reynolds number used is 1000. The effective distance between the main object and the passive controls is analyzed by using the mathematical model so that the drag coefficient on the main object is compared with the simulated one.

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“…Zhou ve arkadaşları [11][12] [14] çalışmalarında bir silindir etrafına yerleştirilen yüksek geçirgenlik oranındaki (β=0,7) dairesel dış silindiri, iç silindire bağlı Reynolds sayısı ReDi=9000 olan akış ortamında incelemişler ve delikli dış silindirin türbülans istatistikleri, türbülans kinetik enerjisi ve Reynolds gerilmelerinin azaltılmasında önemli bir etkiye sahip olduğunu ortaya koymuşlardır. Oruç [15], daha aerodinamik geometriye sahip elipse benzer bir delikli dış silindiri akış yapısının kontrolünde denemiştir. Durhasan ve arkadaşları [16] dairesel silindir arkasındaki akışı delikli yarım silindir yardımıyla kontrol etmeye çalışmıştır.…”

Section: Introductionunclassified

Altıgen Delikli Silindirin Geçirgenlik Oranının Silindir Arkasındaki Akış Bölgesine Etkisi

Atar¹,

Baş²,

Küçük³

2016

Çukurova Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi

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ÖzDaha önce yapılan çalışmalarda dairesel silindir arkasındaki daimi olmayan akış yapısı, silindirin etrafına farklı geometri, çap ve geçirgenlik oranlarına sahip delikli dış silindirler yerleştirilerek kontrol edilmeye çalışılmıştır. Bu çalışmada ise, dairesel silindirin kendisi üzerinde açılan, d=10 mm çapında, altıgen deliklerin silindir arkasında meydana gelen akışın özellikleri üzerindeki etkisi incelenmiştir. Deliksiz geçirgen olmayan bir silindir ve geçirgenlik oranları β=0,2, 0,3, 0,4, 0,5, 0,6, 0,7 olmak üzere toplam 6 farklı delikli geçirgen silindirlerin arkasında oluşan akış yapısı Parçacık Görüntülü Hız Ölçümü (PIV) yöntemi ile incelenmiştir. Silindirlerin herbirinin çapı D=100 mm ve bu çapa bağlı Reynolds sayısı Re D =10000'dir. Deneylerde su yüksekliği hw=400 mm olarak sabit tutulmuş ve akış görüntüleri h L =200 mm yükseklikteki orta düzlemden alınmıştır. D=100 mm çaplı deliksiz silindir ile kıyaslandığında delikli silindirlerdeki deliklerden çıkan jet akışının daimi olmayan akış yapısına olumlu etkisi açık şekilde görülmektedir. Reynolds gerilmelerinde geçirgenlik oranının artışıyla birlikte düşüş gözlemlenmiştir. Hız alanları içinde Ancak β≥0,6 oranından itibaren deliklerden çıkan jet akışının etkisi azalmaktadır. Akış kontrolünde dairesel silindir üzerinde açılan altıgen delikler için β=0,6 geçirgenlik oranının en etkili oran olduğu gözlemlenmiştir. Anahtar Kelimeler: Akış kontrolü, Pasif kontrol, PIV, Girdap kontrolü, Silindir The Effect of Hexagonal Perforated Cylinder Porosity on Flow Region Formed Behind the Cylinder AbstractIn previous studies, unsteady flow structure formed behind the circular cylinder was tried to control by outer perforated cylinder with various inner/outer cylinders diameter ratio (D i /D d ) and porosity ratios (β). In this study, perforation was applied directly on the cylinder (without any outer cylinder) and effect of this process on flow downstream of the cylinder body was investigated. Flow structure formed downstream of a nonpermeable cylinder and six different permeable (β=0.2, 0.3, 0.4, 0.5, 0.6, 0.7) cylinders was studied via Particle Image Velocimetry (PIV) technique.Diameter of each cylinder was D=100 mm and Reynolds Number was Re D =10000 based on these diameters. During all experiments, * Sorumlu yazar (Corresponding author): Mustafa Atakan AKAR, aakar@cu.edu.tr

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Passive control of flow structures around a circular cylinder by using screen

Cited by 52 publications

References 33 publications

Surface pressure distribution on patterned cylinders under simulated atmospheric boundary layer winds

Surface pressure distribution on patterned cylinders under simulated atmospheric boundary layer winds

Mathematical Modeling of Drag Coefficient Reduction in Circular Cylinder Using Two Passive Controls at Re = 1000

Altıgen Delikli Silindirin Geçirgenlik Oranının Silindir Arkasındaki Akış Bölgesine Etkisi

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