NDLI: Experiments in Active Stall Control of a Twin-Spool Turbofan Engine

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Dirk, C. Leinhos Stephen, G. Scheidler Fottner, Leonhard Grauer, Frank Hermann, Jakob Mettenleiter, Manuel Orthmann, Armin
Copyright Year	2002
Abstract	The aerodynamic stability of aero engine compressors must be assured by active control systems in all operating conditions when the design surge margin is reduced in order to improve efficiency. While this has been investigated only on compressor rigs and single-spool engines in the past, this study focuses on the active control of the LARZAC 04 twin-spool turbofan. The objective is to demonstrate potential benefits, problems and solutions and also to provide a data base for numerical modeling and simulation of the capabilities of active control. Three different control strategies have been employed each of which refers to a specific operating condition and instability inception of the engine: The attenuation of disturbances travelling at rotor speed by modulated air injection into the LPC in the high speed range, the recovery of fully developed LPC stall at low speeds with a minimized amount of air and finally a constant air recirculation (HPC exit to LPC inlet) for stabilizing the compression system at different speeds based on the monitoring of a stability parameter. The injector is mounted upstream of the LPC and has ten circumferentially distributed nozzles for air injection into the tip region of the first rotor. The injected air which is either taken from an external source or from bleed air ports at the HPC exit is controlled by high-bandwidth direct-drive-valves. Disturbances travelling at rotor speed can be detected and attenuated with modulated air injection leading to a delay of stall onset. Fully developed rotating stall in the LPC was eliminated by asymmetric injection based on modal control strategies with less air than needed with constant air injection. By using online-stability-monitoring it is possible to initiate constant air recirculation when approaching the surge line, though the current design of the injector does not allow for large extension of the operating range for all spool speeds.
Sponsorship	International Gas Turbine Institute
Starting Page	9
Ending Page	20
Page Count	12
File Format	PDF
ISBN	0791836061
DOI	10.1115/GT2002-30002
e-ISBN	0791836010
Volume Number	Volume 1: Turbo Expo 2002
Conference Proceedings	ASME Turbo Expo 2002: Power for Land, Sea, and Air
Language	English
Publisher Date	2002-06-03
Publisher Place	Amsterdam, The Netherlands
Access Restriction	Subscribed
Subject Keyword	Compression Stability Computer simulation Rotors Control systems Valves Compressors Aircraft engines Surges Engines Design Databases Gates (closures) Simulation Turbofans Ejectors Nozzles Delays
Content Type	Text
Resource Type	Article

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