Abteilungen - Triebwerksakustik - Passive Strömungsbeeinflussung
Passive methods of flow control in compressor cascades have been subject to investigations in various research projects. Vortex generators attached to the stator suction surfaces have been able to decrease the total pressure loss by an amount of 5%. Cross flow fences have shown a potential of loss reduction in the region of 10% of the total pressure losses. The deflection could be increased by 2°. This is accompanied by a isentropic increase of the axial compressor stage in the region of 1,3%. A different approach uses vortex generators in front of the leading edges of a comnpressor stage. Those vortex generators induce a longitudinal vortex in the passage that enhances the mixing of the boundary layer and the high momentum main passage flow. The energetization of the boundary layer leads to s higher capability of the flow to overcome the strong adverse pressure gradient in the passage without separation. The total pressure loss is decreased by an amount of about 8% compared to the base flow case. Passive methods can help to enhance the thermodynamic cycle and the overall efficiency of compressors and will be more interesting as the fossil energy prices are likely to rise in the near future.