Steady Entrance Flow in a Strongly Curved Tube

Abstract

Laser Doppler velocity measurements were performed on the entry flow of a strongly curved tube with the parabolic entry profile, in which a maximum curvature ratio, defined as the ratio of tube radius to the radius of curvature a/R, achieved is 1/2. Both axial and secondary velocities were measured, describing the fairly complete flow field. Intensified curvature effects cause the secondary flow, and the maximum secondary flow velocity went up to 90% of the cross-sectional averaged axial velocity in the curved tube with a/R = 1.2. Due to this enhanced secondary flow, separation of secondary flow is found near the inner wall.