Experimental and numerical investigation into the effects of tip configurations on the aerodynamic performance and loss structure of turbine blade tip

To investigate the effects of blade tip configurations on the aerodynamic performance and loss structure of turbine cascades, aerodynamic measurements incorporating blade tip coolant ejection are conducted on a transonic cascade test rig. A comparative aerodynamic analysis is conducted between four tip configurations: (1) classical squealer tip (REF) as the reference case; (2) pressure-side inclined rim modification (IR); (3) IR configuration with partitioned cavity via a divider wall (IRDW); and (4) IR configuration integrated with suction-side cutback rim (IRCR). Results indicate that at all three exit isentropic Mach number conditions, as for the aerodynamic performance, IRCR slightly surpasses IR, which outperforms IRDW, with REF performing the lowest. Quantitatively, in the terms of experimental results, compared with REF, area-averaged total pressure loss coefficient of IRCR decreases by 13.11%, 16.62%, and 18.14% at exit isentropic Mach number equal to 0.7, 0.8, and 0.9, respectively. The influencing regions of different tip shapes primarily concentrate on the loss of tip leakage vortex (TLV) and upper passage vortex (UPV). For three improved shapes, the limited development of tip leakage flow and the weaker interaction between the mainstream and secondary flow lead to the lower TLV loss. The swirling and consumption of TLV to UPV and their interaction impact the UPV development. Overall, three improved tip shapes can enhance the cascade aerodynamic performance significantly and offer a meaningful reference for the progression of gas turbine design.