Active Separation Control with Pulsed Jets in a Critically Loaded Compressor Cascade

In this contribution the impact of active flow control by means of pulsed blowing in a critically loaded compressor cascade will be described. Because of the high loading of the blades, a fully three-dimensional and complex flowfield is developing. Experimental investigations with active flow control were undertaken to increase the turning and the pressure rise of the stator cascade, by suppressing separation phenomena in the passage flowfield. Two different concepts of actuators were used. First, pulsed blowing out of the endwalls was used to reduce the secondary flow structures. Second, the flow was excited with actuators flush-mounted on the blade's suction surface. The best performance was reached by using both actuator concepts in combination. A multivariable closed-loop control approach was used to control both separation phenomena simultaneously. Heavy disturbances could be compensated and a stabilization of the cascade operation point was achieved.