215 Qualification of the test section

Periodic flow in the wind tunnel is obtained by adjusting the bleeds and the tailboards, obtaining static pressure coefficients from the pressure blade replacing the three middle blades respectively, and ensuring the coefficients are close to the data from the inviscid flow solution.

It can be seen from the figure that the static pressure distributions from the three middle blades are close to each other and agree with the inviscid solution fig. 2.4 , especially for the pressure side. This implies that passage flows around the center blade in the two neighboring passages have almost the same volumetric flows. Therefore, the periodic flow in the blade passages is established and the linear cascade test section is qualified for this study.

The incoming flow from the wind tunnel is also measured at the incoming flow measurement plane in fig. 2.3.1 using hot wire anemometry to ensure the mainstream is uniform and steady. It is shown in fig. 2.5 that the incoming flow has the typical mean flow and turbulence characteristics of a duct flow at different inlet speeds.

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