Surrogates for combustion instabilities in annularcombustors

International audience; While the computational power is still increasing, thus arousing theinterest for high-fidelity simulations, the need of low-order models is also feltto both predict and understand combustion instabilities at low costs. Historicallyapplied to simple systems like longitudinal Rijke tubes to unveil the driven mechanismsleading to instability, they have recently been adapted to more complexconfigurations such as annular combustors. A network model is presented here topredict thermo-acoustic modes in an annular combustion chamber fed by burnersconnected to an annular plenum, typical of modern combustor designs. Explicitexpressions of the growth rate are derived in several cases showing key parameterscontrolling the stability. In more general situations, no explicit solution canbe obtained. Nevertheless, such an analytical model can be solved numerically atlow-cost compared with 3D acoustic tools and high-fidelity simulations. In thisframework, efficient sensitivity techniques and UQ methods can be developed totackle the UQ problem: “How can we assess the risk of instability in industrialcombustors at the predesign stage?”.