Experimental investigation on characteristics of tip leakage blockage in an axial compressor

Rotor passage flow fields are measured by stereoscopic particle image velocimetry (SPIV) in a large-scale low speed axial compressor test facility. The measurements are conducted in conditions of stages with different aerodynamic loading levels, different rotor tip gap sizes and different operating conditions. The variations of blockage inside the rotor passage are analyzed by a quantitative method. The results show that: in the test conditions the distribution of blockage by the tip leakage vortex has the characteristics of non-linearity and non-monotonicity, which means the peak blockage occurs inside the rotor passage; the adverse pressure gradient is the most important physical mechanism for the growing of the blockage; in an environment of adverse pressure gradient the higher the initial mass flow rate in the blockage region, the faster is the growth of blockage, and the higher the initial total pressure deficit, the easier it is to cause stall; intensive turbulent mixing occurs between the tip leakage flow and the mainstream, and the transport of kinetic energy between the mainstream and tip leakage flow by the viscosity and turbulent fluctuation in the turbulent mixing is the main mechanism for blockage decay.