Effect of attack angle on the flow around adjacent circular and rectangular prisms

Abstract

An experimental investigation has been carried out to clarify the flow structure around adjacent circular and rectangular prisms. The measurements of hot-wire for Re= 4.1 x 10³, 9.0 x 10³ and 1.5 x 10⁴, lift and drag force for Re = 1.0 x 10⁴, and in addition the flow visualization experiments for Re = 2.3 x 10³ have been performed in the range of 0° ≤ α ≤ 180°. The adjacent bodies consist of a circular cylinder having 9.5 mm diameter and a rectangular prism having 6 mm x 10 mm cross-section attached to the circular cylinder from its short side in all the cases. The hot wire measurement results showed that the Strouhal number has Reynolds number independence for Re = 4.1x10³, 9.0x10³, and 1.5x10⁴. Sudden peaks in St and lift coefficients are obtained for a similar reason that is reattachment of the separated shear layer in the vicinity of α = 60° and 174°. For the adjacent bodies compared with the bare circular cylinder, 40%, and 25% drag reduction is obtained at α = 0° and 174°, respectively. The obtained results show that the variations of lift coefficient, drag coefficient, and Strouhal number are strictly subjected to the attack angle.

Keywords

• Adjacent Bluff Bodies
• Circular Cylinder
• Rectangular prism
• Drag Coefficient
• Strouhal number

Hücum açısının temas halinde dairesel ve dikdörtgen prizma etrafındaki akış üzerine etkisi

Abstract

Temas halindeki dairesel ve dikdörtgen prizmalar etrafındaki akış yapısını aydınlatmak için deneysel bir araştırma yapılmıştır. Re= 4.1 x 10³, 9.0 x 10³ ve 1.5 x 10⁴ için kızgın telle hız, Re = 1.0 x 10⁴ için kaldırma ve sürüklenme kuvveti ölçümleri ve ayrıca Re = 2.3 x 10³ için akış görüntüleme deneyleri 0° ≤ α ≤ 180° aralığında gerçekleştirilmiştir. Temas halindeki cisimler, 6 mm x 10mm kesite sahip dikdörtgen bir prizma ile 9.5mm çapına sahip dairesel bir silindirden oluşmaktadır. Kızgın tel ölçüm sonuçları, Strouhal sayısının Re = 4.1x10³, 9.0x10³ ve 1.5x10⁴ sayıları için Reynolds sayısından bağımsız olduğunu göstermiştir. Kaldırma ve Strouhal sayılarındaki ani pikler akış ayrılma tabakasının α = 60° ve 174° civarında yeniden tutunmasıyla ilgili aynı nedenden kaynaklanmaktadır. Temas halindeki cisimler ile sade silindir karşılaştırıldığında sürüklenme katsayısı α = 0° ve 174°'de sırasıyla %40 ve %25 azaltılmıştır. Elde edilen sonuçlar, kaldırma, sürüklenme katsayısı ve Strouhal sayısı değişimlerinin hücum açısına bağlı olduğunu göstermiştir.

Keywords

• Temas halindeki cisimler
• Dairesel silindir
• Dikdörtgen prizması
• Sürüklenme katsayısı
• Strouhal sayısı

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