Enhancement of highly-loaded axial compressor stage performance using rotor blade tip tailoring: Part I - Numerical design studies

The present paper presents results from investigations performed in the AdComB project with funding of the 5th European Framework. The project is focused on advanced 3D blade design, with a main sub task being to reduce compressor rotor tip leakage flow and enhance performance at high levels of aerodynamic loading by using rotor blade tip tailoring. A number of different approaches were taken to introduce additional tip design features to a conventionally designed and stacked baseline rotor. Numerical and experimental results of the first advanced rotor (3D-1), which had identical sectional geometry but tip forward sweep and some degrees of dihedral, were reported by Gümmer et al. (2003) and Rohkamm et al. (2003). A refined distribution of sweep and some extra camber for tip work recovery were applied to the datum rotor, giving the second advanced rotor (3D-2). The third advanced rotor (3D-3) was derived from investigations carried out to assess benefits of rotor tip chord increase, combined with the same level of sweep as the 3D-2 aerofoil. The blade leading edge was maintained whilst increasing tip chord and extending the blade rearwards. A 3D-Navier- Stokes solver was used for simulations of the 3D-2 and 3D-3 rotor flow field. The numerical predictions showed a benefit in terms of stall margin for the 3D-2 rotor. The predictions for the 3D-3 rotor promised a further increase in stall margin and efficiency. Both designs were manufactured and taken to test on the large-scale low-speed research compressor rig (LSRC) at Technical University Braunschweig, see part II of this paper (Rohkamm et al. (2005)). In the present part I of the paper, detailed results of the numerical 3D studies are presented, discussed, and compared to those of the datum design.