The present authors have reported a noticeable reduction in the aerodynamic performance of turbine vanes which had been modified as a result of commonly applied repair processes. These tests were done at a low turbulence level to isolate the profile-only effect. In the present research, the effect of the same profile modification on the performance of the vanes was investigated at engine representative flow conditions by increasing the turbulence level and length scale. Since the tested vane profiles in the present research were synthesized using the profile of LPT vanes, the turbulence level was maintained at around 4% and the length scale was set at 2 cm. In the present investigation, calculations with computational fluid dynamics and measurements in a transonic cascade rig were carried out. The high turbulence level in the cascade rig was produced using a passive turbulence-generating grid and in CFD by specifying the desired level and length scale. Coordinates of the baseline profile were obtained from the LPT vanes of an in-service turboshaft engine using 3D optical scanning and digital modeling. The repaired vanes were synthesized using profiles representative of two specific repair types. In both methods, flow visualization was carried out using axial density gradient or schlieren and exit total pressure was obtained numerically or using a multihole probe. Further insight into the flow phenomenon was obtained by surface flow visualization in the cascade rig using a graphite and paraffin oil mixture and by computed surface pressure distributions on the vane. The shock pattern in the cascade for low and high turbulence flows was similar; however, the surface flow pattern exhibited a significant difference for the two conditions. The total pressure ratio and cascade loss also showed some differences.
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