Blar i NTNU Open på forfatter "Orchini, Alessandro"
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Analysis of Thermoacoustic Modes in Can-Annular Combustors Using Effective Bloch-Type Boundary Conditions
von Saldern, Jakob; Orchini, Alessandro; Moeck, Jonas (Peer reviewed; Journal article, 2020)Heavy-duty gas turbines are commonly designed with can-annular combustors, in which all flames are physically separated. Acoustically, however, the cans communicate via the upstream located compressor plenum, or at the ... -
Degenerate perturbation theory in thermoacoustics: high-order sensitivities and exceptional points
Orchini, Alessandro; Magri, Luca; Silva, Camilo F.; Mensah, Georg; Moeck, Jonas (Peer reviewed; Journal article, 2020)In this study, we connect concepts that have been recently developed in thermoacoustics, specifically (i) high-order spectral perturbation theory, (ii) symmetry-induced degenerate thermoacoustic modes, (iii) intrinsic ... -
Effect of an Azimuthal Mean Flow On the Structure and Stability of Thermoacoustic Modes in an Annular Combustor Model with Electroacoustic Feedback
Humbert, Sylvain; Moeck, Jonas; Orchini, Alessandro; Paschereit, Oliver (Peer reviewed; Journal article, 2020)Thermoacoustic oscillations in axisymmetric annular combustors are generally coupled by degenerate azimuthal modes, which can be of standing or spinning nature. Symmetry breaking due to the presence of a mean azimuthal ... -
A Non-Compact Effective Impedance Model for Can-To-Can Acoustic Communication: Analysis and Optimization of Damping Mechanisms
von Saldern, Jakob; Orchini, Alessandro; Moeck, Jonas (Peer reviewed; Journal article, 2021)Can-annular combustors can feature azimuthal instabilities even if the acoustic coupling between the individual cans is weak. Recently, various studies have focused on modeling the acoustic communication between adjacent ... -
Nonlinear interaction between clustered unstable thermoacoustic modes in can-annular combustors
von Saldern, Jakob; Moeck, Jonas; Orchini, Alessandro (Peer reviewed; Journal article, 2020)A can-annular combustor consists of a set of nominally identical cans, in which the flames burn in an essentially isolated manner. However, adjacent cans are able to communicate acoustically, which provides dynamic coupling ... -
Perturbation theory of nonlinear, non-self-adjoint eigenvalue problems: Semisimple eigenvalues
Orchini, Alessandro; Mensah, Georg; Moeck, Jonas (Peer reviewed; Journal article, 2021)We discuss high-order adjoint based degenerate perturbation theory of semisimple eigenvalues resulting from nonlinear eigenvalue problems, which are typical of acoustic problems and vibrational analysis. The theory is ... -
Perturbation theory of nonlinear, non-self-adjoint eigenvalue problems: Simple eigenvalues
Mensah, Georg; Orchini, Alessandro; Moeck, Jonas (Peer reviewed; Journal article, 2020)The study of the vibrational modes and stability of a given physical system is strongly tied to the efficient numerical evaluation of its eigenvalues. The operators governing the eigenproblem are, in general, nonlinear in ... -
Reduced-order modelling of thermoacoustic instabilities in can-annular combustors
Orchini, Alessandro; Pedergnana, Tiemo; Buschmann, Philip Erik; Moeck, Jonas; Noiray, Nicolas (Peer reviewed; Journal article, 2022)Thermoacoustic instabilities in stationary gas turbines may cause high-amplitude limit cycles, leading to damaged components and costly down-time. To better understand the physical origin of such instabilities in a can-annular ... -
Symmetry-breaking in thermoacoustics: Theory and experimental validation on an annular system with electroacoustic feedback
Humbert, Sylvain; Moeck, Jonas; Paschereit, Oliver; Orchini, Alessandro (Peer reviewed; Journal article, 2023)In this study, we investigate experimentally the linear and nonlinear thermoacoustic response of an annular combustor model with electroacoustic feedback to study the effects that various types of asymmetric modifications ... -
Thermoacoustic modes of intrinsic and acoustic origin and their interplay with exceptional points
Orchini, Alessandro; Silva, Camilo; Mensah, Georg; Moeck, Jonas (Peer reviewed; Journal article, 2020)We propose a general classification of all the modes of a given thermoacoustic system into two sets: one of acoustic origin and one of intrinsic thermoacoustic (ITA) origin. To do this, the definition of intrinsic modes, ...