Effects of Flow Control on the Aerodynamics of a Tandem Inlet Guide Vane
Vandeputte, Thomas William
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An aerodynamic investigation was performed to assess the effectiveness of combined boundary layer suction and trailing edge blowing at reducing the blade profile losses and the wake momentum deficit of a cascade of tandem IGV's operating at realistic flow conditions. Two trailing edge blowing designs were tested: metal-angle blowing, which oriented the blowing jets very near to the blade exit angle, and deviation-angle blowing, which oriented the blowing jets at a significant deviation angle from the blade exit angle. Both blowing designs used the same boundary layer suction arrangement. A linear cascade of five IGV's was tested with a flap deflection angle of 40 degrees and an inlet Mach number of 0.3. The Reynolds number based on the overall IGV chord length for these experiments was greater than 500,000. The inlet and exit angles of the IGV at this flap setting were 0 degrees and 55 degrees, respectively. Tests performed with no flow control showed significant suction surface flow separation that generated large wakes with high losses and large momentum deficits. The application of boundary layer suction reduced the baseline pressure loss coefficient and wake momentum thickness by 22%. A suction mass flow of 0.4% of the passage flow was used to obtain these results. The addition of metal-angle blowing with the suction resulted in total reductions of 48% and 38% for the pressure loss coefficient and wake momentum thickness. A blowing mass flow of 3.1% of the passage flow was used in addition to 0.4% suction mass flow to obtain these results. The application of the deviation-angle blowing was detrimental to the aerodynamics of the IGV, as both the pressure loss coefficient and wake momentum thickness increased slightly over their suction-only values. This was attributed to a manufacturing defect which distorted the flow of the blowing jet. The results of the deviation-angle blowing experiments were not considered representative of the design intent and reinforced the importance of the hole design for creating a proper blowing jet. While low speed tests of this cascade showed results and trends very similar to those of previous research, the application of flow control proved to be less effective at higher speeds due to the generation of significantly larger wakes.
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