Unsteady flow characteristics in a 90 degree elbow affected by developed, undeveloped and swirling inflow conditions

Iwamoto, Yukiharu*; Kondo, Manabu*; Minamiura, Hirotaka*; Tanaka, Masaaki  ; Yamano, Hidemasa   

LDV measurements in a 90 degree elbow of which the curvature radius coincides with its inner diameter were examined for the cases of inflow from a long pipe, short pipe and swirl generator. Ensemble averaged flow distribution at the Reynolds number of 320000 based on the inner pipe diameter and bulk velocity shows that shortening the upstream pipe length to 4.9D from 10D induces the flow separation downstream of the elbow.