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Investigation of Unsteady Flow Behavior in Transonic Compressor Rotors with LES and PIV Measurements

Hah, Chunill and Voges, Melanie and Müller, Martin W. and Schiffer, H.-P. (2009) Investigation of Unsteady Flow Behavior in Transonic Compressor Rotors with LES and PIV Measurements. 19th ISABE Conference, 7.-11. Sep. 2009, Montréal, Canada.

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Abstract

In the present study, unsteady flow behavior in a modern transonic axial compressor rotor is studied in detail with large eddy simulation (LES) and particle image velocimetry (PIV). The main purpose of the study is to advance the current understanding of the flow field near the blade tip in an axial transonic compressor rotor near the stall and peak-efficiency conditions. Flow interaction between the tip leakage vortex and the passage shock is inherently unsteady in a transonic compressor. Casing-mounted unsteady pressure transducers have been widely applied to investigate steady and unsteady flow behavior near the casing. Although many aspects of flow have been revealed, flow structures below the casing cannot be studied with casing-mounted pressure transducers. In the present study, unsteady velocity fields are measured with a PIV system and the measured unsteady flow fields are compared with LES simulations. The currently applied PIV measurements indicate that the flow near the tip region is not steady even at the design condition. This self-induced unsteadiness increases significantly as the compressor rotor operates near the stall condition. Measured data from PIV show that the tip clearance vortex oscillates substantially near stall. The calculated unsteady characteristics of the flow from LES agree well with the PIV measurements. Calculated unsteady flow fields show that the formation of the tip clearance vortex is intermittent and the concept of vortex breakdown from steady flow analysis does not seem to apply in the current flow field. Fluid with low momentum near the pressure side of the blade close to the leading edge periodically spills over into the adjacent blade passage. The present study indicates that stall inception is heavily dependent on unsteady behavior of the flow field near the leading edge of the blade tip section for the present transonic compressor rotor.

Document Type:Conference or Workshop Item (Paper)
Title:Investigation of Unsteady Flow Behavior in Transonic Compressor Rotors with LES and PIV Measurements
Authors:
AuthorsInstitution or Email of Authors
Hah, ChunillNASA Glenn RC
Voges, Melaniemelanie.voges@dlr.de
Müller, Martin W.Technische Universität Darmstadt
Schiffer, H.-P.Technische Universität Darmstadt
Date:September 2009
Refereed publication:Yes
In ISI Web of Science:No
Status:Published
Keywords:compressor, transonic, piv, les, unsteady flow
Event Title:19th ISABE Conference
Event Location:Montréal, Canada
Event Type:international Conference
Event Dates:7.-11. Sep. 2009
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Virtual Engine and Validation Methods
Location: Köln-Porz
Institutes and Institutions:Institute of Propulsion Technology > Engine Measurement Systems
Deposited By: Melanie Voges
Deposited On:09 Nov 2009 15:42
Last Modified:27 Aug 2012 08:55

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