AN EXAMINATION OF A 3D CORNER-STEP EXPERIMENT

This paper presents results of LDV measurements in a complex three-dim ensional (3D) turbulent flow. The experimental configuration studied, shown in Fig. 1, provides a complex 1 parameter (step height) three-di mensional flow with two-dimensional (2D) relaxation limits in the span wise direction (that is, 2D channel flow and 2D backstep). Note that t his flow is more complex than the simple 2D back-step described by Eat en and Johnston, 1981, AIAA Journal, vol. 19, pp. 1093-1100. However, when spanwise limits are taken out from either side of the centerline the flow relaxes to two well studied 2D flows. On the block side, the spanwise limit results in a 2D turbulent channel flow. On the step sid e, the spanwise limit results in the 2D back-step flow. In the center region of the facility, however the flow is strongly 3D. The data pres ented here, was taken with a three component laser Velocimetry system, thus all three velocity components can be measured simultaneously. Th e results presented here clearly indicate that this flow provides a co mplex 3D flow for turbulence model calibration with the added attracti on of the 2D spanwise limits. In the region within two step-heights ei ther side in span of the streamwise step edge, secondary flows are obs erved. In addition, a spanwise evolving streamwise reattachment length is seen. The prediction of the secondary motions along with the spanw ise evolving streamwise reattachment length found here will provide a challenging test for any turbulence model. (C) 1998 Elsevier Science I nc. All rights reserved.