Title page for ETD etd-12032009-193449


Type of Document Master's Thesis
Author Holzinger, Felix
URN etd-12032009-193449
Title Development of a Concept for Forced Response Investigations
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
O'Brien, Walter F. Jr. Committee Chair
Schiffer, Heinz-Peter Committee Chair
Bohn, Jan Helge Committee Member
Hampe, Manfred J. Committee Member
Keywords
  • flutter
  • forced response
  • transonic
  • compressor
  • excitation system
  • air injection
Date of Defense 2009-11-20
Availability restricted
Abstract
Striving to improve performance and lower weight of aircraft engines, modern compressor blades become thinner and lighter but higher loaded resulting in an increased vulnerability towards flutter. This trend is further aggravated through blisk designs that diminish structural damping and therewith flutter margin. Modern 3D wide-chord blade designs result in complex structural behaviors that add to the difficulty of correctly predicting flutter occurrence.

To counteract above tendencies by driving the physical understanding of flutter and thereby helping to improve aero engine design tools, free flutter as well as forced response will be investigated in the 1.5 stage transonic compressor at TU Darmstadt. Aim of the forced response campaign is to determine the system damping in the stable compressor regime. Hence a novel excitation system capable of dynamically exciting specific rotor blade modes is needed. It is aim of the present work to find a promising concept for such a system.

In the present work, the requirements for an excitation system to be used in the TUD compressor are defined with respect to achievable frequency, phase controllability, transferred excitation level, mechanical robustness, integrability and cleanliness. Different excitation system concepts, i.e. oscillating VIGVs, rotating airfoils, tangential and axial air injection are investigated numerically. An evaluation of the results obtained through 2D numerical studies proposes axial air injection as the most favorable concept.

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