Increasing Blade Turning by Active Flow Control and Tandem Configurations: A Comparison

摘要

An experimental analysis of the baseline flow of a linear cascade equipped with a set of highly loaded single compressor blades reveals complex three-dimensional secondary flow phenomena. To reduce the resulting losses and to increase the working range of the blading before stall occurs, two different approaches are examined: Firstly the single blades have been replaced by tandem configurations. The enhanced flow guidance for the tandem configuration is realised by the nature of the design of this two-vane-configuration. For those, two different loading splits are analysed to examine the influence on the secondary flow development. The geometry and the turning task have been kept constant for all variations. As a second approach the single blades have been equipped with Active Flow Control (AFC) devices to inject pressurized air at the suction side of the stator blades to influence the passage flow. Two different AFC geometries and two mass-flow rates of the actuation have been examined. A comparison of both approaches (single vanes with AFC vs. tandem vanes) regarding the effect on the secondary flow structures and the resulting efficiency of the flow manipulation has been carried out. Oil flow pattern and wake measurements are performed for the non-influenced flow of the single blades and evaluated against AFC measurements and tandem measurements respectively. By the use of tandem blades as well as the single blades with AFC the resulting losses can be reduced while realizing a higher pressure rise across the stage and increasing the blades working range.