Session: 32-02 Turbine Tip Flows

Paper Number: 153738

Experimental Assessment of Tip Loss Variation in LPT Blades With Tip Height, Squealer Geometry, and Coolant Flow Rate 

This study presents an extensive experimental campaign aimed at finely sampling the loss generated by leakage flow in Low-Pressure Turbine (LPT) blades. A total of 20 different combinations of influential parameters affecting tip leakage flow generation were investigated. Specifically, tests were conducted for both flat tip and squealer tip configurations with varying tip gaps. For the squealer configuration, different Reynolds numbers (Re=100,000 and Re=200,000) and coolant flow ratios were also tested. Additionally, tests were performed for both Reynolds numbers without a tip gap to provide a reference spanwise loss distribution characterizing the passage vortex effect alone.

By comparing these gap-free spanwise distributions with results from experiments with a tip gap, the contribution to loss production due to the tip vortex alone was isolated. Five-hole pressure probe data acquired in a downstream tangential plane provided a clear view of the effects of flow parameter variations on the tip leakage vortex core, the spanwise distribution of losses, and flow angles. Tip leakage losses estimated for the different cases were compared with the flat tip case, allowing the generation of a response surface accounting for the delta losses with respect to the reference.

These surfaces were fitted with a Gaussian Process (GP), and the results presented in this paper are expected to provide useful guidance for designers regarding loss expectations as a function of the analyzed parameters.

Presenting Author: Daniele Petronio Università degli Studi di Genova - DIME

Presenting Author Biography: Research Fellow at the Laboratory of Aerodynamics and Turbomachinery of the University of Genova. My research activity is focused on the aeroengine Low-Pressure Turbine (LPT) and includes the acquisition of data concerning LPT performances and detailed boundary layer measurements, performed by Particle Image Velocimetry and
Laser Doppler Velocimetery. I am also gaining experience in data analytic tools, post-processing techniques and system modeling.

Authors:

Daniele Petronio Università degli Studi di Genova - DIME
Virginia Bologna University of Genova
Daniele Simoni University of Genova
Monica Gily Avio Aero