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CHARACTERISTICS OF TIP CLEARANCE FLOW INSTABILITY IN A TRANSONIC COMPRESSOR

Hah, Chunill and Voges, Melanie and Müller, Martin W. and Schiffer, Heint-Peter (2010) CHARACTERISTICS OF TIP CLEARANCE FLOW INSTABILITY IN A TRANSONIC COMPRESSOR. ASME Turbo Expo 2010 Power for Land, Sea and Air, 14.-18. Juni 2010, Glasgow, UK.

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Abstract

In the present study, unsteady flow phenomena due to tip clearance flow instability in a modern transonic axial compressor rotor are studied in detail. First, unsteady flow characteristics due the oscillating tip clearance vortex measured with the particle image velocimetry (PIV) and casing-mounted unsteady pressure transducers are analyzed and compared to numerical results with a large eddy simulation (LES). Then, measured characteristic frequencies of the unsteady flow near stall operation are investigated. The overall purpose of the study is to advance the current understanding of the unsteady flow field near the blade tip in an axial transonic compressor rotor near the stall operating condition. Flow interaction between the tip leakage vortex and the passage shock is inherently unsteady in a transonic compressor. The currently applied PIV measurements indicate that the flow near the tip region is unsteady even at the design condition. This self-induced unsteadiness increases significantly as the compressor operates toward the stall condition. PIV data show that the tip clearance vortex oscillates substantially near stall. The calculated unsteady characteristics 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 spectral analysis of measured end wall and blade surface pressure shows that there are two dominant frequencies near stall. One frequency is about 40-60% of the rotor rotation and the other dominant frequency is about 40-60% of the blade passing frequency (BPF). The first frequency represents the movement of a large blockage over several consecutive blade passages against the rotor rotation. The second frequency represents traditional tip flow instability, which has been widely observed in subsonic compressors. The LES simulations show that the second frequency is due to movement of the instability vortex.

Document Type:Conference or Workshop Item (Speech, Paper)
Title:CHARACTERISTICS OF TIP CLEARANCE FLOW INSTABILITY IN A TRANSONIC COMPRESSOR
Authors:
AuthorsInstitution or Email of Authors
Hah, ChunillNASA Glenn Research Center
Voges, Melaniemelanie.voges@dlr.de
Müller, Martin W.Technische Universität Darmstadt, GLR
Schiffer, Heint-PeterTechnische Universität Darmstadt, GLR
Date:July 2010
Refereed publication:Yes
In ISI Web of Science:No
Status:Published
Keywords:PIV, LES, transonic, compressor, flow instability
Event Title:ASME Turbo Expo 2010 Power for Land, Sea and Air
Event Location:Glasgow, UK
Event Type:international Conference
Event Dates:14.-18. Juni 2010
Organizer:IGTI
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:02 Aug 2010 14:57
Last Modified:12 Dec 2013 20:59

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