Loss map for aeroengine turbine blade equipped with tip inlet squealer

Abstract

The full loss data for the IS (inlet squealer) tip with the wide changes of squealer height (h_st) and tip clearance (h) are measured in an aeroengine turbine blade cascade of downstream-to-upstream velocity ratio (VR) = 2.01 with a five-hole probe instrumentation system. The loss map shows that the variation of IS tip loss with hst/s is strongly dependent upon h/s, contrary to the full squealer tip case. The IS tip loss tends to increase with h_st/s for low h/s, whereas it tends to decrease with h_st/s for high h/s. The noticeable loss reduction by the IS tip can be attained when h/s ≥ 1.5 % especially for high hst/s. The comparison among IS tip losses in three cascades of VR = 1.2 (weak reaction), 2.01 (medium reaction), and 2.4 (strong reaction) reveals that the IS tip-to-flat tip loss ratio is affected considerably by VR (turbine reaction).