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research-article

ACCURATE ESTIMATION OF PROFILE LOSSES AND ANALYSIS OF LOSS GENERATION MECHANISMS IN A TURBINE CASCADE

[+] Author and Article Information
Davide Lengani

DIME - Universitá di Genova, Genova, Italy
davide.lengani@edu.unige.it

Daniele Simoni

DIME - Universitá di Genova, Genova, Italy
daniele.simoni@unige.it

Marina Ubaldi

DIME - Universitá di Genova, Genova, Italy
marina.ubaldi@unige.it

Pietro Zunino

DIME - Universitá di Genova, Genova, Italy
pietro.zunino@unige.it

Francesco Bertini

GE AvioAero S.r.l., Torino, Italy
francesco.bertini@avioaero.it

Vittorio Michelassi

GE Oil & Gas S.r.l., Firenze, Italy
vittorio.michelassi@ge.com

1Corresponding author.

ASME doi:10.1115/1.4037858 History: Received August 06, 2017; Revised August 30, 2017

Abstract

The paper analyzes losses and the loss generation mechanisms in a low-pressure turbine cascade by Proper-Orthogonal-Decomposition (POD) applied to measurements. Total pressure probes and time resolved particle image velocimetry (TR-PIV) are used to determine the flow field and performance of the blade with steady and unsteady inflow conditions varying the flow incidence. The total pressure loss coefficient is computed by traversing two Kiel probes upstream and downstream of the cascade simultaneously. This procedure allows a very accurate estimation of the total pressure loss coefficient also in the potential flow region affected by incoming wake migration. The TR-PIV investigation concentrates on the aft portion of the suction side boundary layer downstream of peak suction. POD applied to this portion of the domain provides a statistical representation of the flow oscillations by splitting the effects induced by the different dynamics. The paper also describes how POD can dissect the loss generation mechanisms by separating the contributions to the Reynolds stress tensor from the different modes. The steady condition loss generation, driven by boundary layer streaks and separation is augmented in presence of incoming wakes by the wake-boundary layer interaction and by the wake dilation mechanism. Wake migration losses have been found to be almost insensitive to incidence variation between nominal and negative (up to -9deg), while at positive incidence the losses have a steep increase due to the alteration of the wake path induced by the different loading distribution.

Copyright (c) 2017 by ASME
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