Next Article in Journal
Investigation on the Flow in a Rotor-Stator Cavity with Centripetal Through-Flow
Previous Article in Journal
Effect of Distortion on Turbofan Tonal Noise at Cutback with Hybrid Methods
Article Menu

Export Article

Open AccessArticle
Int. J. Turbomach. Propuls. Power 2017, 2(4), 17; https://doi.org/10.3390/ijtpp2040017

A POD-Based Procedure for the Split of Unsteady Losses of an LPT Cascade

1
DIME—University of Genoa, Via Montallegro 1, I-16145 Genoa, Italy
2
GE AvioAero SRL, Torino I-10040, Italy
This paper is an extended version of our paper in Proceedings of the European Turbomachinery Conference ETC12, 2017, Paper No. 324.
*
Author to whom correspondence should be addressed.
Academic Editor: Raúl Vázquez Díaz
Received: 6 June 2017 / Revised: 28 September 2017 / Accepted: 4 October 2017 / Published: 16 October 2017
View Full-Text   |   Download PDF [7263 KB, uploaded 16 October 2017]   |  

Abstract

A time-resolved particle image velocimetry (TR-PIV) system has been employed to investigate the unsteady propagation of upstream wakes in a low-pressure turbine cascade. Data are obtained in the steady state condition and for two passing wake reduced frequencies. The study is focused on the identification and split of the different dynamics responsible for deterministic and random oscillations, thus loss generation by means of a new procedure based on proper orthogonal decomposition (POD). The paper takes advantage of the properties of POD that reduce the data set to a low number of modes that represent the most energetic dynamics of the system. It is clearly shown that the phase averaged flow field can be represented by a few number of POD modes related to the wake passing event for the unsteady cases. Proper orthogonal decomposition is also able to capture flow features affecting the instantaneous flow field not directly related to the wake passage (i.e., the vortex shedding phenomenon induced by the intermittent separation developing between adjacent wakes), which are smeared out in the phase averaged results. A procedure exploiting the biorthogonality condition of the POD modes, and the related temporal coefficients, has been developed for the quantification of the contribution due to the different POD modes to the overall turbulence kinetic energy production, or, equivalently, the mean flow energy dissipation rate. Results into the paper clearly show that losses due to wake migration, boundary layer and vortex shedding related phenomena can be distinguished and separately quantified for the different tested conditions. View Full-Text
Keywords: proper orthogonal decomposition; wake-boundary layer interaction; unsteady losses; turbulent kinetic energy production proper orthogonal decomposition; wake-boundary layer interaction; unsteady losses; turbulent kinetic energy production
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Lengani, D.; Simoni, D.; Ubaldi, M.; Zunino, P.; Bertini, F. A POD-Based Procedure for the Split of Unsteady Losses of an LPT Cascade. Int. J. Turbomach. Propuls. Power 2017, 2, 17.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Int. J. Turbomach. Propuls. Power EISSN 2504-186X Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top