Enhancement of blade tip cooling with different position on tip cooling slot

One of the leading causes of thermally induced failure in gas turbine blade tip is a tip leakage flow. To protect blade tip efficiently from strong tip leakage flow, slot cooling is adopted in blade tip considering the application of additive manufacturing. For slot cooling scheme in blade tip, slot location ranging from PS slot to SS slot is a crucial role in film cooling effectiveness of blade tip. Therefore, we investigated the effect of the cooling-slot location on film cooling effectiveness and flow characteristics of blade tip with slot cooling considering the application of additive manufacturing. The local film cooling effectiveness on the blade tip floor and upper surface of the rim are obtained using pressure sensitive paint method. The case of coolant discharge from the PS slot was both stable and evenly spread, resulting in an outstanding coolant coverage of the entire tip regions. However, under severe effect of hot main gas flow behavior, the case of the SS slot resulted in an uneven FCE distributions over the entire tip region from the LE to the TE region. Under the studied tip gaps and coolant mass flow rates, the PS slot configuration provided a superior blade tip cooling performance under most operating conditions, but the SS slot configuration provided an outstanding cooling performance on blade tip only at a large amount of coolant mass flow rate compared to PS slot. Thus, the blade tip with a PS slot is recommended as a robust cooling design. However, the blade tip with a SS slot may have a limited application for design and off-design conditions.