Pengendalian Aliran Pasif pada Silinder Sirkular dengan Inlet Disturbance Body Berbentuk Silinder Elip (AR = 1/4)

This investigation to observe the information about fluid interaction phenomena from fluid momentum flow attach on surface contour of two bluff body shapes, there are elliptic cylinder and circular cylinder. This characteristic predicts aerodynamic force on the bluff bodies are related with drag reduction. Elliptic cylinder (AR = 1/4) and circular cylinder are arranged tandem position with longitudinal gap (G/D = 1), and are located elliptic cylinder as inlet disturbance body on upstream and circular cylinder as downstream body. The inlet disturbance body has four shapes, first elliptic cylinder without modification geometry, and the others with modification geometry to cut in front of elliptic cylinder with configuration 5%, 10%, and 15% of major axis length (B). Fluid flow characteristics investigate experimentally on open-circuit subsonic wind tunnel. The experimental results obtain the phenomena fluid interactions are indicated by reattachment process which is related with appearing bubble and massive separation on the surface contour of modified elliptic cylinder. Separating and reattching process is increasing flow transition from laminar to turbulent boundary layer until the postponement of massive separation position on surface contour of circular cylinder. To arrange elliptic cylinder (AR = 1/4) with modification geometry to cut front side 10% from length of major axis as inlet disturbance body gives significant results to reduce drag of circular cylinder. All investigations are running at Reynolds Number of 6.4x104 based on circular cylinder diameter. in Bahasa Indonesia: Penelitian ini adalah untuk mendapatkan informasi mengenai fenomena interaksi aliran dari momentum fluida yang attach pada kontur permukaan bluff body berbentuk silinder elip maupun silinder sirkular. Karakteristik tersebut digunakan untuk memprediksi gaya aerodinamika pada kedua benda tersebut, terutama berkenaan dengan reduksi gaya hambat (drag reduction). Kedua bentuk bluff body (silinder elip dan silinder sirkular) ditempatkan dalam susunan tandem, dengan menempatkan silinder elip dengan axis ratio (AR = 1/4) sebagai inlet disturbance body yang ditempatkan pada sisi upstream. Bentuk geometri silinder elip (AR = 1/4) memiliki empat variasi yaitu silinder elip yaitu tanpa pemotongan sisi depan, dan ketiga lainnya dengan memodifikasi silinder elip dengan memotong sisi depan 5%, 10%, dan 15% dari panjang sumbu mayornya (B). Silinder sirkular ditempatkan pada sisi downstream dalam posisi tandem dengan jarak longitudinal (G/D) = 1. Karakteristik aliran melintasi silinder elip (A