In the design of an axial compressor, many designers take advantage of this technology and employ contracted shroud. What is its impact on tip leakage flow and overall performance of the axial compressor? What is its mechanism? In this paper, the NASA Rotor67 is taken as a research case, and parameterized study is conducted to investigate the effects of shrouds with different inclined angles. The inclined angles range from 0° to 13°. Based on the above described plan, numerical simulations are conducted to the original rotor67 and its modified versions with inclined shroud. To remove factors that might interfere the results, original Rotor 67 and all the blades with modified shroud should be compared to their optimal design status. Adjoint optimization is used to give the optimum blade corresponding to each shroud with different blade inclined angles.
Then adjoint optimization was used again to give the optimum meridional flowpath for all the cases with different shroud inclined angles. This provides a powerful tool to evaluate the accuracy of the aforementioned prediction. A detailed comparison is made between the original flowpath and the optimized ones.
Numerical results are analyzed in detail between original Rotor67 and its modified versions. The results show that the shroud inclined angle has an effect on the overall performance of the blade. It will also redistribute the velocity triangles and the chordwise distribution of aero load in the tip region. Hence it exerts great influence on the tip leakage flow field in the meantime. Shroud with suitable inclined angles can suppress the developing of leakage vortex , and the best-inclined angle for rotor 67 is found to be roughly 11°.