Patent attributes
As air passes through the airflow channels (46) between the blades (10) of a compressor impeller, boundary layers build up on the blade (10) surfaces. These low momentum masses of air are considered a blockage and loss generators. Ultimately, the boundary layer on the suction side of the blade (20) will separate, causing stall and reversed flow. Reversed flow will occur until a stable pressure ratio with positive volume flow rate is reached. When the pressure ratio becomes unstable again, the cycle will repeat. Introducing a slit (12) or a series of perforations (28) on the compressor wheel blade (10) allows the air to communicate between the pressure side (18) and the suction side (20) of the blade, which allows the boundary layer to stay attached longer. The invention allows for various shapes, positions, lengths and widths, locations, and arrangements of either a slit (12) or a series of perforations (28) on the compressor blade (10) in order to accomplish the objectives of delaying surge conditions by prolonging the boundary layer adherence to the suction side (20) of the compressor blade (10) and of maintaining a low level of noise emission, ease of manufacturing, and structural integrity.
