Skip to main content
European Commission logo print header

Advanced coupling of low order combustor simulations with thermoacoustic modelling and controller design

Final Report Summary - ACOULOMODE (Advanced coupling of low order combustor simulations with thermoacoustic modelling and controller design)

The ACOULOMODE project addressed the problem of combustion instability – a damaging phenomenon which is the key barrier to low NOx emissions from aero-engines and power gas turbines.
It (i) achieved a breakthrough advance in how we are able to predict combustion instability in feasible computational times and without the need for experiments and (ii) yielded significant new insights into how combustion instability arises and how it can be suppressed.

For prediction of combustion instability, the project applied a coupled approach in which the two physical phenoma at play – the acoustic waves and the flame – are captured using different treatments. These are then coupled. The acoustic waves are captured using linear, low-dimensional analytical models while the flame is captured using high fidelity simulations. Crucially, in terms of ensuring feasible computational times, the project showed that faster “incompressible” simulations accurately capture the nonlinear response of the flame. Furthermore, when coupled with the acoustic treatment, the project demonstrated the very first good predictions of both the frequency and amplitude of oscillations resulting from combustion instability. The computational tool embedding the linear acoustic models and coupling them with the nonlinear flame response has been released open source (www.oscilos.com) and is being widely used.

The project generated new insights into combustion instability, addressing the generation, propagation and damping of acoustic waves and the unsteady response of the flame. It showed that temperature variations resulting from flame unsteadiness can act as a significant source of acoustic waves and developed new models to capture this effect. It showed how the combustor flowfield, with its changes in temperature and thermodynamic properties, affects the acoustic field and that accurately capturing this is key to good prediction. It developed new models for how (and under what conditions) holes damp the acoustic waves, yielding new insights for the design of acoustic dampers. It also developed the first active control strategy able to guarantee suppression of oscillations once they are established, and investigated the interactions of neighbouring flames.

ACOULOMODE’s successes have spawned several subsequent projects, funded by the ERC, the Engineering and Physical Sciences Research Council in the UK and industry.