Effect of Rib Location on the Heat Transfer and Cooling Characteristics at the Squealer Tip in Turbine Stage[J]. 2018, 52(5): 116-124.
DOI:
Effect of Rib Location on the Heat Transfer and Cooling Characteristics at the Squealer Tip in Turbine Stage[J]. 2018, 52(5): 116-124.DOI: 10.7652/xjtuxb201805017.
Effect of Rib Location on the Heat Transfer and Cooling Characteristics at the Squealer Tip in Turbine Stage
Numerical methods are adopted to investigate the heat transfer and film cooling characteristics at three squealer tips with double cavities in a gas turbine first stage rotor blade. At the squealer tips
the ribs are located at 25%
50% and 75% of axial chord
respectively
and perpendicular to the chord direction
so they are denoted rib25
rib50 and rib75
respectively. The total-to-total isentropic efficiency in the turbine stage
the heat transfer coefficient and the film cooling effectiveness at the blade tip were calculated and also compared with the conventional squealer tip. The results show that
without film cooling
there exists high heat transfer area on the cavity floor near the leading edge for both conventional squealer tip and double-cavity squealer tip. Compared with the conventional squealer tip
the double-cavity squealer tip can improve the total-to-total isentropic efficiency of the turbine stage. Among four squealer tips(conventional squealer tip
rib25
rib50 and rib75)
the aerodynamic performance in rib50 turbine stage is the best
the total-to-total isentropic efficiency can be improved by 0.43%. However
the area-averaged heat transfer coefficient at the rotor blade tip is increased by 13.7% compared with the conventional squealer tip. When the film cooling holes are arranged at the rotor tip camber line
the film cooling effect on the tip cavities is significantly improved because more coolant is accumulated in the cavities
which can be attributed to the blade rotation and the limitation of the rib to coolant. Compared with the conventional squealer tip
the three kinds of double-cavity squealer tips perform superior film cooling effect at the tips. Among the four squealer tips
rib50 performs the best film cooling effect at the rotor tip and also has the highest aerodynamic performance in the turbine stage. With film cooling
the total-to-total isentropic efficiency in the turbine stage equipped with rib50 tip can be increased by 0.36%
the area-averaged heat transfer coefficient at the tip is reduced by 14.4% and the area-averaged film cooling effectiveness can be improved by 31.8% in contrast to the conventional squealer tip.
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references
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