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Visualization and PIV Measurements of the Transonic Flow around the Leading Edge of an eroded Fan Airfoil

Klinner, Joachim and Hergt , Alexander and Beversdorff, Manfred and Willert, Christian (2012) Visualization and PIV Measurements of the Transonic Flow around the Leading Edge of an eroded Fan Airfoil. In: Conference proceedings online. 16th Int Symp on Applications of Laser Techniques to Fluid Mechanics, 09-12 July, 2012, Lisbon, Portugal.

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Official URL: http://ltces.dem.ist.utl.pt/lxlaser/lxlaser2012/program.asp

Abstract

The influence of blade deterioration on the time-averaged and instantaneous flow around a fan airfoil is investigated by PIV, schlieren imaging and high speed shock-shadowgraphs in a transonic cascade windtunnel. In addition to a global characterization of the time-averaged flow using PIV, the instantaneous passage shock position was extracted from single shot PIV measurements by matching the tracer velocity across the normal shock with an exponential fit. From this the relaxation time of paraffine-ethanol seeding was verified to have a response time in the sub-microsecond range. The instantaneous shock positions, defined by the onset of the exponential decay, are assigned to a probability density distribution in order to obtain the average position and the width of fluctuations. Finally the distributions from the generic blunted edge geometry and the unaffected reference geometry are compared under near stall and under choked conditions. At similar back-pressure conditions the passage shock of the blunted edge geometry is located further upstream in comparison to the reference geometry. The amplitude of shock fluttering is significantly higher for the blunted edge. In order to extract the frequency range of the shock motion the direct shadow of the shock wave was tracked in high-speed shadowgraphs and spectrally analyzed. A comparison of the power spectra of the shock motion indicates that under choked conditions the blunted edge geometry exhibits a more continuous spectrum with a broader frequency range. The paper discusses details on the experimental implementation such as a specifically designed purged light sheet probe.

Document Type:Conference or Workshop Item (Speech, Paper)
Title:Visualization and PIV Measurements of the Transonic Flow around the Leading Edge of an eroded Fan Airfoil
Authors:
AuthorsInstitution or Email of Authors
Klinner, Joachimjoachim.klinner@dlr.de
Hergt , AlexanderUNSPECIFIED
Beversdorff, ManfredUNSPECIFIED
Willert, ChristianUNSPECIFIED
Date:9 July 2012
Journal or Publication Title:Conference proceedings online
Refereed publication:Yes
In ISI Web of Science:No
Status:Published
Keywords:fan blade erosion, particle response, shock unsteadiness, shock oscillation, boundary layer separation
Event Title:16th Int Symp on Applications of Laser Techniques to Fluid Mechanics
Event Location:Lisbon, Portugal
Event Type:international Conference
Event Dates:09-12 July, 2012
HGF - Research field:Aeronautics, Space and Transport, Aeronautics, Space and Transport
HGF - Program:Aeronautics, Aeronautics
HGF - Program Themes:Propulsion Systems, Propulsion Systems
DLR - Research area:Aeronautics, Aeronautics
DLR - Program:L ER - Engine Research, L ER - Engine Research
DLR - Research theme (Project):L - Fan and Compressor Technologies, L - Virtual Engine and Validation Methods
Location: Köln-Porz
Institutes and Institutions:Institute of Propulsion Technology > Engine Measurement Systems
Institute of Propulsion Technology > Fan and Compressor
Deposited By: Joachim Klinner
Deposited On:09 Aug 2012 11:04
Last Modified:22 Aug 2012 11:16

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