Acoustic modes in combustors with complex impedances and multidimensional active flames

摘要: two approaches for solving the corresponding nonlinear eigenvalue problem are proposed. The first one is based on an asymptotic expansion of solution, baseline being acoustic modes and frequencies a steady (or passive) flame appropriate boundary conditions. This method allows quick assessment any mode stabilitybutisvalidonlyforcaseswherethecouplingbetweenthe flameandtheacousticwavesissmallinamplitude. second approach iterative algorithm where quadratic solved at each subiteration. It more central processing unit demanding but remains valid even in cases response flametoacousticperturbationsislarge.Frequency-dependentboundaryimpedancesareaccountedforinbothcases. A parallel implementation Arnoldi used to solve large that arises fromthespacediscretization ofthe Helmholtzequation.Several academicandindustrial testcasesareconsideredto illustrate potential method.