Research Papers

Effects of Compressor Tip Injection on Aircraft Engine Performance and Stability

[+] Author and Article Information
Wolfgang Horn

Department of Engine Performance, MTU Aero Engines GmbH, Dachauer Straße 665, 80995 München, Germanywolfgang.horn@mtu.de

Klaus-Jürgen Schmidt

Department of Engine Performance, MTU Aero Engines GmbH, Dachauer Straße 665, 80995 München, Germanyklaus-juergen.schmidt@mtu.de

Stephan Staudacher

Institute for Aircraft Propulsion Systems, University of Stuttgart, Pfaffenwaldring 6, 70569 Stuttgart, Germanystaudacher@ila.uni-stuttgart.de

J. Turbomach 131(3), 031011 (Apr 09, 2009) (9 pages) doi:10.1115/1.2988159 History: Received December 19, 2007; Revised February 04, 2008; Published April 09, 2009

This analytical study discusses the system aspects of active stability enhancement using mass flow injection in front of the rotor blade tip of a high pressure compressor. Tip injection is modeled as a recirculating bleed in a performance simulation of a commercial turbofan engine. A map correction procedure accounts for the changes in compressor characteristics caused by injection. The correction factors are derived from stage stacking calculations, which include a simple correlation for stability enhancement. The operational characteristic of the actively controlled engine is simulated in steady and transient states. The basic steady-state effect consists of a local change in mass flow and a local increase in gas temperature. This alters the component matching in the engine. The mechanism can be described by the compressor-to-turbine flow ratio and the injection temperature ratio. Both effects reduce the cycle efficiency resulting in an increased turbine temperature and fuel consumption at constant thrust. The negative performance impact becomes negligible if compressor recirculation is only employed at the transient part power and if valves remain closed at the steady-state operation. Detailed calculations show that engine handling requirements and temperature limits will still be met. Tip injection increases the high pressure compressor stability margin substantially during critical maneuvers. The proposed concept in combination with an adequate control logic offers promising benefits at transient operation, leading to an improvement potential for the overall engine performance.

Copyright © 2009 by American Society of Mechanical Engineers
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Figure 1

Simplified engine configuration

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Figure 2

Schematic representation of tip injection

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Figure 3

Correlation for stage stability enhancement by steady tip injection

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Figure 4

Performance model embedded in a control simulation environment

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Figure 5

Schematic influence of recirculation on the compressor operating point

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Figure 6

HPC operating lines at reference condition

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Figure 7

Effect of HPC recirculation on LPC operating line

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Figure 8

Impact of recirculation on performance parameters at sea level

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Figure 9

Influence of the recirculating mass flow at different injection temperatures on performance parameters

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Figure 10

Impact of the recirculating bleed on HPC surge margin

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Figure 11

Comparison between HPC handling bleed and the recirculating bleed at low power

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Figure 12

Parametric representation of the transient excess power

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Figure 13

Acceleration from idle to take-off rating at sea level for different recirculation settings

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Figure 14

Operating lines and the surge margin benefit for an acceleration from the idle to take-off rating

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Figure 15

Steady state LPC operating lines and acceleration from the idle to take-off rating




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