Control of the Unsteady Flow Structure Behind the Cylinder with Passive Control Method

In this study, it is aimed to control flow structure downstream of inner cylinder with seven different diameters (Di= 30, 40, 50, 60, 70, 80, 90mm) by a surrounding outer cylinder that have β=0.5 porosity. The diameter of outer cylinder was chosen as 100mm. The perforation hole diameters of the cylinder were 10mm. The water height was kept constant during experiments as hw=400mm.The depth-averaged free stream velocity was U=100m/s which corresponded to a Reynolds number ReD=10000 based on outer cylinder diameter. Flow characteristics downstream of cylinder was investigated by using particle image velocimetry (PIV) technique. PIV experiments were performed at the mid-section of water 200mm. It has been observed that the perforated outer cylinder decreased vortex shedding downstream of inner cylinder with different diameters (Di=30, 40, 50, 60, 70, 80, 90mm). For high diameter ratios Di/Do≥0.7 perforated outer cylinder lost its effect on the flow control.

Silindir Arkasýndaki Daimi Olmayan Akýþ Yapýsýnýn Pasif Yöntemle Kontrolü

Bu çalýþmada, Di=30, 40, 50, 60, 70, 80, 90 mm olan yedi farklý çapta iç silindir arkasýnda meydana gelen akýþ yapýsý, etrafýna yerleþtirilen β=0.5 geçirgenlik oranýna sahip silindirle kontrol edilmeye çalýþýlmýþtýr. Dýþ silindirin çapý Dd=100 mm olarak seçilmiþtir. Silindir üzerine açýlan deliklerin çapý d=10 mm’dir. Deneyler süresince su yüksekliði hw=400 mm’de sabit tutulmuþtur. Suyun hýzý U=100 mm/s ve buna karþýlýk dýþ çapa baðlý Reynolds sayýsý ReD=10000’dir. Silindir arkasýnda meydana gelen akýþ yapýsý PIV tekniði kullanýlarak incelenmiþtir. PIV deneyleri 200 mm’de orta düzlemde gerçekleþtirilmiþtir. Delikli silindirin, farklý çaplardaki silindir (Di=30, 40, 50, 60, 70, 80, 90 mm) arkasýnda meydana gelen akýþ yapýsýnda girdap kopmalarýnýn azaldýðý gözlenmiþtir. Yüksek çap oranlarýnda (Di/Dd≥0.7) delikli dýþ silindir akýþ kontrolü üzerindeki etkinliðini kaybetmektedir.