Flow Control via Rotor Trailing Edge Blowing in Rotor/Stator Axial Compressor

An experimental study is presented of flow control of the rotor wake in a rotor/stator axial compressor. The objective is to quantify the reduction in the stator forced response due to flow blowing from the rotor trailingedge. The experiment was conducted in a low-speed, large-scale axial compressor at both near-design and high time-mean blade loading. The blowing cases considered are 35, 72, and 105% of the nonblowing wake momentum defect, which ranges from 1.3 to 3.7% of the compressor mass flow at near-design loading. Instrumentation include slanted hot wire to acquire three-dimensional ensemble-averaged rotor wake profile and fast-response pressure gauges embedded within the stator blades at midspan. Results show that the development of the near wake (15% chord downstream of trailing edge) is very much loading dependent; the same amount of blowing momentum has an effect on the velocity defect at near-design loading but not at high loading. Farther downstream, trailing-edge blowing is effective in energizing the wake. The decrease in magnitude of transverse gust is essentially linear with the wake momentum increase due to the blowing flow. Data show reduction in the stator unsteady force amplitude for all blowing cases tested. With the wake momentum at 72% of that for the wakeless flow, force amplitude reduction of 25 and 35% are realized for the near-design and high loading cases, respectively.