Turbine blade tips are critical regions of a turbomachine in which small geometric differences can cause extreme alterations in the obtained thermal performance. For this reason, it is increasingly important for experiments and simulations to more closely represent real geometry features. One commonly absent detail is the presence of welding beads on the cavity of the blade tip, which are an inherent by-product of the blade manufacturing process and have not been previously studied. This paper therefore investigates the impact of cavity welding beads on the heat transfer coefficient and film cooling effectiveness of a high pressure turbine blade tip with an open trailing edge squealer geometry.

Measurements are performed on a linear cascade at engine realistic Mach and Reynolds numbers. Two cooled blade tip geometries were tested: a baseline geometry without welding beads, and a case with representative welding beads added to the tip cavity. Combinations of two coolant mass flows and two tip gaps were analysed. Pressure sensitive paint has been used to measure the adiabatic film cooling effectiveness, which is supplemented by heat transfer coefficient measurements obtained via transient infrared thermography. Complementary CFD was performed to better understand the identified flow features, examine the effect of a moving wall boundary condition and to investigate the impact of altering the position and size of the welds. Drawing on all of this data, the paper details the impact of the welding beads on in-engine thermal performance and examines strategies to mitigate their impact.


Aerothermal Effect of Cavity Welding Beads on a Transonic Squealer Tip

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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