LIMOUSINE will focus on the limit cycle behaviour of the unstable pressure oscillations, and on the resulting mechanical vibrations and materials fatigue. Several earlier projects have addressed the prediction of marginal acoustic stability of combustion systems, and worked on design measures on burners to avoid acoustic instability. However, instability is hard to avoid in the entire operating range of an engine, from idle to nominal power, or between summer and winter operation. When it occurs, it is essential to know the size and effect of the instability. Some instabilities are harmless in amplitude and frequency, while others may be fatal for the engine. The impact on the combustor is assessed by gas turbine operators by the decrease in lifetime. An important research aim of LIMOUSINE is the development of correlations, based on engine settings, to quantify the lifetime reduction due to elevated vibration amplitudes. The project will provide both training of young scientists and further insight by research.
The project aim in research is to predict the mechanical vibration in a gas turbine engine and the resulting fatigue and time to failure. Active and passive control processes will be developed to allow safe operation of the gas turbine on a variety of fuels and operating conditions. The activities are divided into work packages. In summary, these are:
- Correlation of liner vibration and fatigue.
- Prediction of liner vibration due to two-way fluid-structure interaction with hot gas flows by analytical and numerical methods.
- Experimental and theoretical modelling of the feedback between combustion, pressure waves and aerodynamic effects .
- Experimental and theoretical modelling of transient heat transfer to the liner in situations of limit cycle flow variations.
- Prediction of the characteristics (limit cycle amplitude, frequency, etc.) of the self-sustaining oscillations by analytical and numerical methods.
- Implementation of active control to manipulate the limit cycle and measure growth rates.
The project aim in training is to create a new generation of young engineering scientists, that are highly skilled in the development and application of design and operational tools, to keep thermo acoustic induced vibration and fatigue within limits at all circumstances.