33 Summary

In this chapter, the flow field in the linear cascade test section is characterized and visualization. Some important results are summarized:

1. At normal operating conditions, the turbulent boundary layer on the tip-endwall has a displacement thickness of 0.24cm (1.3%C), which is typical in a gas turbine engine.

2. From the analysis of mid-span flow near the blade, it is clear that a separation region exists on the pressure surface from 0.05 to 0.\hSp/C. Transition may occur on the suction side downstream of Ss/C = 1.2.

3. The unloading effect of tip clearance can be observed from the static pressure distribution on the near-tip surfaces. This effect becomes larger with the increase in tip clearance level, especially near the leading edge, where loading could be negative at the largest tip clearance.

4. From the surface flow visualization, it is found that the horseshoe vortex system still appears at the smallest tip clearance level. A separation bubble forms along the

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