| Gas path analysis is frequently used in engine health monitoring systems to predict engine performance under damaged conditions. Users of this method have indicated a need for research on the aerodynamic effects of damage on individual engine components.;A streamline curvature program for analyzing flow in axial flow turbines is investigated for its ability to predict the performance of turbines with damaged blades. The program is altered to allow the tip losses to be concentrated in the tip region. Use of the program to analyze a turbine with simulated tip damage shows that overall engine performance parameters, such as efficiency and power output, are only slightly affected by increased tip clearance and that analysis with concentrated tip losses causes less of a change than with distributed tip losses. A greater effect is observed on the change in temperatures and pressures, across the annulus, at the rotor exit. The development of a new streamline curvature program is recommended for analyzing modern turbine geometries.;A method for manufacturing cascade blades with damage is developed. Preliminary aerodynamic tests of the blades is performed using trailing edge damage simulated by a semicircular cutout having a diameter 25% of chord. Qualitative results are presented which suggest that vortices are generated at the edge of the cutout. |
