STRUCTURAL DESIGN OF AIRCRAFT ENGINES

RTO-AVT-VKI 207

From January 24 to 27, 2012

von Karman Institute, Rhode-St-Genèse, Belgium

The constant improvement of aircraft engine performance during the last 30 years had leaded towards complex components, reduced masses and higher temperatures. As a consequence, the structural loads are significantly increased in complex assemblies, with highly loaded parts, and with narrow security margins regarding static stresses, temperatures, cyclic loads and vibration. This lecture series objective is to explain the challenges of structural design.

The first day will address the engine global behaviour. A lecture on the whole engine dynamics will overview how to model the different elements of the engine to study the dynamic behaviour of the assembled system while respecting the design criteria. Foreign object damage and fan blade out will describe the methodologies currently used to perform simulations in the compression system to predict the integrity of the structure. A presentation on thermal stresses will review the thermo-mechanical analysis, comprising model construction and development, model validation and the use of the data to support the design process.

The second day will be focused on bladed disk design, from the standard aeromechanical design practices to more complex problems such as aeroelastic stability. Forced response prediction will propose an alternative approach to estimate the forced response early before the engine testing. A lecture on flutter will present a description of the steps in the design analysis process. This condition is known as “mistuning” and has the potential to affect significantly flutter and forced response, particularly for blisks.

The third day will address high cycle fatigue, and design strategies to mitigate forcing and the state of the art on aeroelasticity research. The non linear dynamics lecture will discuss the damping properties caused by friction, aerodynamic viscous and hysteretic dissipation effects on the alternating stresses. A major goal in the development process of rotating turbomachinery turbine blades is to prevent them from high cyclic fatigue (HCF) failure. Design strategies to mitigate unsteady forcing presents a successful example of resonant-stress reduction through mitigation of unsteady forcing during the aerodynamic design of turbine components. Experimental research on aeroelasticity will elucidate possible methods for the experimental investigation of aerodynamic damping and forcing, as well as relevant measurement techniques.

The last day will be focused on the mechanic behaviour of the material and life estimation. A global overview on material science will be given. Then the process and rules to estimate the life of components versus fatigue and creep will be presented. Two consecutive lectures on materials will associate the temperatures of different engine parts with material alternatives. The lecture will continue with a description of the general failure mechanisms, fatigue failure mechanisms and mechanical testing to allow life predictions. Creep life prediction and TMF life prediction in turbines cover the fundamentals of creep and fatigue behaviour from a material point of view.

The Lecture Series directors are E. Seinturier, Turbomeca, and Prof. G. Paniagua, Turbomachinery and Propulsion Department, von Karman Institute.

Timetable

Tuesday 24 January 2012

• 08:45    Registration
• 09:15    Welcome address
• 09:30    Aircraft Engine
  E. Seinturier, Turbomeca, France
• 11:15    Whole Engine dynamics
  A. Vial, Snecam, France
• 14:00    Foreign object damage and fan blade out
  H. Chalons, Safran, Turbomeca, France
• 15:45    The part Thermo-Mechanical Analysis Plays in the Design of Gas Turbines
  S.J. Mills, Rolls-Royce UK, England
• 17:00    Reception

Wednesday 25 January 2012

• 09:00    Aeromechanical design
  E. Seinturier
• 10:45    Forced response prediction
  E. Seinturier
• 14:00    Bladed disks: Flutter
  R. Corral, ITP, Spain
• 15:45    Bladed disks: Mistuning
  R. Corral

Thursday 26 January 2012

• 09:00    Bladed disks: Non linear dynamics
  J. Szwedowicz, Alstom Power, Switzerland
• 10:45    High cycle fatigue
  J. Szwedowicz
• 14:00    Design strategies to mitigate unsteady forcing
  J.P. Clark, Wright Patterson AFB, USA
• 15:45    Experimental research on aeroelasticity                
  D. Vogt, Royal Institute of Technology, Sweden

Friday 27 January 2012

• 09:00    Material fundamentals
  G. Sjöberg, Volvo Aero Corporation, Sweden
• 10:45    Material fundamentals
  T. Hansson, Volvo Aero Corporation, Sweden
• 14:00    Creep Life Prediction in Turbines
  S. M. Bagnal, Rolls-Royce UK, England
• 15:45   Low Cycle Fatigue
  S. M. Bagnal
• 17:00    End of Lecture Series

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Location : von Karman Institute for Fluid Dynamics, Rhode-St-Genèse, Belgium