Novel high-pressure turbine purge control features for increased stage efficiency

Schädler, Rainer; Kalfas, Anestis I.; Abhari, Reza S.; Schmid, Gregor; Kampe, Tilmann auf dem; Prabhu, Sunil

doi:10.22261/68mk5v

Cited by 3 publications

(2 citation statements)

References 18 publications

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“…This behaviour is consistent with what typically observed in studies concerning rotor secondary flows such as Regina et al [40], Jenny et al [41] and Ong et al [42]. Unsteady aerodynamic data collected on the same turbine configuration confirm the radial migration of the rotor hub secondary flows up to 40% of the span (Schädler et al [43]). The low heat transfer level in the region is then explained by the presence of lowmomentum fluid in the wake of the detaching hub passage vortex.…”

Section: Resultssupporting

confidence: 88%

Infrared thermography with non-uniform heat flux boundary conditions on the rotor endwall of an axial turbine

Gazzini

Schädler

Kalfas

et al. 2016

Meas. Sci. Technol.

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It is technically challenging to measure heat fluxes on the rotating components of gas turbines, yet accurate knowledge of local heat loads under engine-representative conditions is crucial for ensuring the reliability of the designs. In this work, quantitative image processing tools were developed to perform fast and accurate infrared thermography measurements on 3D-shaped film-heaters directly deposited on the turbine endwalls. The newly developed image processing method and instrumentation were used to measure the heat load on the rotor endwalls of an axial turbine. A step-transient heat flux calibration technique is applied to measure the heat flux generated locally by the film heater, thus eliminating the need for a rigorously iso-energetic boundary condition. On-board electronics installed on the rotor record the temperature readings of RTDs installed in the substrate below the heaters in order to evaluate the conductive losses in the solid. Full maps of heat transfer coefficient and adiabatic wall temperature are produced for two different operating conditions, demonstrating the sensitivity of the technique to local flow features and variations in heat transfer due to Reynolds number effect.

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Section: Resultssupporting

confidence: 88%

Infrared thermography with non-uniform heat flux boundary conditions on the rotor endwall of an axial turbine

Gazzini

Schädler

Kalfas

et al. 2016

Meas. Sci. Technol.

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“…In order to further validate the time-averaged and dynamic measurement accuracy of the newly developed FRAP-4S, comparison with the traditional 5HP (Treiber et al, 1998) and FRAP-2S (Porreca et al, 2007;Behr et al, 2008;Regina et al, 2013;Schädler et al, 2017) are provided in the following sections of the article. The 5HP is also used to derive the time-averaged flow field.…”

Section: Further Instrumentationmentioning

confidence: 99%

A novel 4-sensor fast-response aerodynamic probe for non-isotropic turbulence measurement in turbomachinery flows

Chasoglou

Mansour²,

Kalfas

et al. 2018

J. Glob. Power Propuls. Soc.

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In modern computational studies for turbomachinery applications, time, length scales and isotropy of turbulent structures are important for representative modelling. To this end, experimental data are essential to validate the numerical tools. The current article presents the development and application of a newly designed 4-sensor Fast Response Aerodynamic Probe (FRAP-4S) enabling time-resolved measurement of the three-dimensional unsteady flow velocity vector in turbomachines. The miniature multi-sensor probe demonstrates a 4 mm probe-tip. In the first part of this article the design, manufacturing and calibration results of the FRAP-4S are presented in detail. To assess the newly developed probe accuracy, comparison against traditional instrumentation developed at the Laboratory for Energy Conversion is also provided. In the second part of this work, measurements are performed at the rotor exit of a one-and-a-half stage, unshrouded and highly-loaded axial turbine configuration. The results showed increased level of unsteadiness and turbulence levels with peak-to-peak fluctuation from 5 to 35%. More importantly, in some regions stream-wise unsteadiness was found to be ten times higher, compared to the cross-wise components, an indication of the high degree of anisotropy.

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Analysis of the Loss Production Mechanism Due to Cavity–Main Flow Interaction in a Low-Pressure Turbine Stage

Barsi

Lengani

Simoni

et al. 2022

Journal of Turbomachinery

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In the present work URANS simulations are presented to describe the unsteady interaction process between the flow ingested/ejected from a cavity system and the main flow evolving into a Low Pressure Turbine stage. Particular care is posed on the analysis of the loss generation mechanisms acting outside the stator row and in the rear part of the axial gap separating the cavity flow ejection section and the leading edge plane of the downstream rotor row. The simulated geometry reproduces a typical engine cavity configuration, with upstream and downstream rotor rows reproduced by means of moving bars. Experimental results have been used to validate the simulations. This experimental data cannot explain and quantify alone the overall interaction process between the cavity flows and the main flow. The results of a simulation made by removing the domain of the cavity have been employed in order to better highlight and quantify the effects due to main flow and cavity flows interaction on total pressure loss. A deep inspection of the loss amount along the axial direction makes evident that losses generated in the vane row are basically increased prior to enter into the downstream rotor bars, due to cavity main flow interaction.

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Novel high-pressure turbine purge control features for increased stage efficiency

Cited by 3 publications

References 18 publications

Infrared thermography with non-uniform heat flux boundary conditions on the rotor endwall of an axial turbine

Infrared thermography with non-uniform heat flux boundary conditions on the rotor endwall of an axial turbine

A novel 4-sensor fast-response aerodynamic probe for non-isotropic turbulence measurement in turbomachinery flows

Analysis of the Loss Production Mechanism Due to Cavity–Main Flow Interaction in a Low-Pressure Turbine Stage

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