Detailed measurements using pneumatic probe traverses, blade static pressure tappings and laser anemometry are made in the third stage of a large scale, low speed, four stage, axial flow, research compressor.
Inlet conditions show well ordered ‘two dimensional’ flow from approximately 40 to 85% annulus span. Outside of this region, reduced total pressure due to upstream leakage losses aod endwall effects results in high incidence to the following blade row. As a result, peak suction surface static pressure moves forward along the blade chord for both the huh and tip of stators and rotors. At the blade tip however, the peak suction pressure is maintained with chord due to radial flow on the suction surface being entrained into the tip leakage jet. The extent of rotor chord for which this ‘entrainment’ occurs increases with increasing rotor tip clearance gap. The leakage jet from both stators and rotors is seen to ‘roll up’ into a vortex downstream of their respective blade rows.
