Session Ce - Separated Flows.
ORAL session, Sunday, November 23
305, Moscone Center
A flying-wire system was utilized in conjunction with a rake of nine cross-wire probes to obtain simultaneous velocity measurements in an axisymmetric sudden expansion at a Reynolds number of 41,000. From these measurements, the correlation tensor could be calculated in this flow geometry. Knowledge of the two-point correlation tensor reveals more indept information of the physical attributes of this flow. The two-point correlation tensor allowed for calculation of the integrated length scales in both the radial and axial directions. This gives insight into the growth of structures with increasing downstream distance and at different radial locations through out the sudden expansion. The length scales were calculated by integrating the two-point correlation tensor in the radial direction from the centerline to the outer pipe wall and by integrating between several step heights for the axial direction. Calculated correlations at z/h = 8 and 9 at r/R = 0.46 showed a correlation length of 1/3 step height for the radial direction and 1 step height for the streamwise direction. It was found that the length scales in the radial direction become larger with increasing radius with peaks at \( 0.70 < r/R < 0.81 \) but then decrease slightly towards the pipe wall. In addition to the length scales, various elements of the two-point correlation tensor were also utilized to investigate the anisotropy in the axisymmetric sudden expansion.