Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
The prediction of combustion instabilities is crucial for aircraft engines manufacturers to ensure the reliability and the life span of their engines. To study these phenomena, numerical simulations are more and more often performed. They o er advantages: a wide range of parameters is available, they are safe and inexpensive compared to experiments.
This work presents a rst step in the general study of combustion instabilities. Firstly, several tools for acoustics and combustion are validated. The tests are performed on simple cases which have reference solutions from analytical resolution or measurements, such as one dimensional ames for combustion and rectangular duct for acoustics. The parameters of these cases are close to the more complex ones. Then, the dynamics of a laminar ame are studied. Finally, a laboratory scale conguration is explored. Kinetics for a methane-air mixture are validated as well as the TFLES model for combustion. The AVSP code for acoustics correctly determines the eigenmodes of a simple conguration.
The TFLES model on a pulsed ame has a signicant impact on its dynamics, depending on the thickening factor and the model used. An unstable mode is found for reacting RANS computations of a laboratory scale conguration. An unstable mode is also predicted by AVSP computations with an active ame model. Even if further work is needed to develop these tools, the rst results indicate that they can quickly yield predictions about combustion instabilities.
2014. , 17 p.