Approved

edge of the blade and organized into a clearly defined patch of fluid that stayed close to the rotor suction surface. As the patch convected downstream, it migrated radially toward midspan.

Figure 12. Total temperature contours at axial stations near the 1st rotor trailing edge and at the exit of the computational domain showing that the hub cavity flow had migrated to nearly 40% span.

Figure 12. Total temperature contours at axial stations near the 1st rotor trailing edge and at the exit of the computational domain showing that the hub cavity flow had migrated to nearly 40% span.

Downstream of the blade trailing edge, the migration continued, and the core of the patch readied 40% span by the exit of the blade grid.

Although the secondary flow patterns were determined in large part by the design of the rotor and physics of the rotor flow, the hub cavity flow provided the mechanism to make these features more pronounced, particularly near the leading edge of the blade. Figure 13 compares the secondary flow patterns for the baseline case without leakage flow and the case with hub leakage flow. The secondary patterns were created using restricted particle traces, which neglected the axial velocity component. Figure 13a shows that just downstream of the blade leading edge on the pressure side of the blade; there was a tight leading edge vortical flow region rotating clockwise when viewed from upstream. In the leakage flow case. 13b, the region covered 25% of the span, and a counter-rotating region is evident off the suction surface. The leakage flow, in essence, amplified the secondary flow that existed in the baseline case.

PROPRIETARY RIGHTS LEGEND This technical data and the information embodied herein 1ยป the property of and proprietary to RoHs-Royce Corporation, and shafi not, without prior written permission of Ro8s-Royce Corporation, be disclosed In whole or in part to third partus. This legend shall be included an any reproduction of this data in whole or in pari Copyright 2000. RoBs*Royce Corporation, (unpublished)

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