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Main Title: Physics of prestall propagating disturbances in axial compressors and their potential as a stall warning indicator
Author(s): Eck, Mario
Geist, Silvio
Peitsch, Dieter
Type: Article
Language Code: en
Abstract: Axial compressors in aero engines are prone to suffering a breakdown of orderly flow when operating at the peak of the pressure rise characteristic. The damaging potential of separated flows is why a safe distance has to be left between every possible operating point and an operating point at which stall occurs. During earlier investigations of stall inception mechanisms, a new type of prestall instability has been found. In this study, it could be demonstrated that the prestall instability characterised by discrete flow disturbances can be clearly assigned to the subject of “Rotating Instabilities”. Propagating disturbances are responsible for the rise in blade passing irregularity. If the mass flow is reduced successively, the level of irregularity increases until the prestall condition devolves into rotating stall. The primary objective of the current work is to highlight the basic physics behind these prestall disturbances by complementary experimental and numerical investigations. Before reaching the peak of the pressure rise characteristic flow, disturbances appear as small vortex tubes with one end attached to the casing and the other attached to the suction surface of the rotor blade. These vortex structures arise when the entire tip region is affected by blockage and at the same time the critical rotor incidence is not exceeded in this flow regime. Furthermore, a new stall indicator was developed by applying statistical methods to the unsteady pressure signal measured over the rotor blade tips, thus granting a better control of the safety margin.
Issue Date: 2017
Date Available: 18-Jan-2018
DDC Class: 600 Technik, Technologie
620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
Subject(s): axial compressor stall
stall inception
stall indicator
rotating instabilities
Sponsor/Funder: DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berlin
Journal Title: Applied Sciences
Publisher: MDPI
Publisher Place: Basel
Volume: 7
Issue: 3
Article Number: 285
Publisher DOI: 10.3390/app7030285
ISSN: 2076-3417
Appears in Collections:FG Luftfahrtantriebe » Publications

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