Browsing NTNU Open by Author "Nygård, Håkon Tormodsen"
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Azimuthal flame response and symmetry breaking in a forced annular combustor
Nygård, Håkon Tormodsen; Ghirardo, Giulio; Worth, Nicholas (Peer reviewed; Journal article, 2021)In the current study azimuthal forcing of an annular combustor with swirling flames has been performed to present for the first time the Heat Release Rate (HRR) response to all possible pressure fields of the first azimuthal ... -
Characteristics of self-excited spinning azimuthal modes in an annular combustor with turbulent premixed bluff-body flames
Mazur, Marek; Nygård, Håkon Tormodsen; Dawson, James; Worth, Nicholas (Journal article; Peer reviewed, 2018)In this paper we investigate self-excited azimuthal modes in an annular combustor with turbulent premixed bluff-body stabilised flames. Previous studies have shown that both swirl and equivalence ratio influence modal ... -
The Effect of Rectangular Confinement Aspect Ratio On the Flame Transfer Function of a Turbulent Swirling Flame
Ånestad, Aksel; Ahn, Byeonguk; Nygård, Håkon Tormodsen; Worth, Nicholas (Peer reviewed; Journal article, 2022)The flame transfer function (FTF) has been experimentally investigated for a premixed, turbulent and highly swirled flame in rectangular enclosures with varying aspect ratio. A range of equivalence ratios and inlet bulk ... -
Experimental Measurement of Flame Describing Functions in an Azimuthally Forced Annular Combustor
Nygård, Håkon Tormodsen (Doctoral theses at NTNU;2021:178, Doctoral thesis, 2021)Thermoacoustic instabilities have become an increasingly relevant issue in the search for lower emissions in gas turbines, both for power production and transportation. Adoption of alternative fuels in land based gas ... -
Experimental Study of Damper Position on Instabilities in an Annular Combustor
Mazur, Marek; Nygård, Håkon Tormodsen; Dawson, James; Worth, Nicholas (Chapter, 2018)The present study experimentally investigates the effects of different circumferential damper configurations on the instabilities in an annular combustor. The combustor consists of multiple bluff body swirl stabilized ... -
Flame dynamics of azimuthal forced spinning and standing modes in an annular combustor
Nygård, Håkon Tormodsen; Mazur, Marek; Dawson, James; Worth, Nicholas (Journal article; Peer reviewed, 2018)Azimuthal forcing has been applied to flames in a laboratory scale annular combustor in order to accurately control the azimuthal mode of excitation. A new forcing configuration permitted not only the pressure amplitude, ... -
Flame transfer functions and dynamics of a closely confined premixed bluff body stabilized flame with swirl
Nygård, Håkon Tormodsen; Worth, Nicholas (Journal article; Peer reviewed, 2021)The flame transfer function (FTF) and flame dynamics of a highly swirled, closely confined, premixed flame is studied over a wide range of equivalence ratios and bulk velocities at a fixed perturbation level at the dump ... -
Saturation of flames to multiple inputs at one frequency
Nygård, Håkon Tormodsen; Ghirardo, Giulio; Worth, Nicholas Alexander (Peer reviewed; Journal article, 2023)Existing experimental results show that swirling flames in annular combustors respond with a different gain to acoustic azimuthal modes rotating in either the clockwise or anti-clockwise direction. The ratio R of these two ... -
Symmetry breaking modelling for azimuthal combustion dynamics
Ghirardo, Giulio; Nygård, Håkon Tormodsen; Cuquel, Alexis; Worth, Nicholas (Peer reviewed; Journal article, 2020)Annular combustors can exhibit azimuthal thermoacoustic instabilities, which can rotate as a spinning wave at the speed of sound in the azimuthal direction, oscillate as a standing wave with pressure nodes fixed in space, ... -
Tailoring the gain and phase of the flame transfer function through targeted convective-acoustic interference
Æsøy, Eirik; Nygård, Håkon Tormodsen; Worth, Nicholas; Dawson, James Richard (Peer reviewed; Journal article, 2022)This paper investigates how targeted interference between two well characterized sources of hydrodynamic disturbances can modify the response of premixed bluff body stabilised flames with and without swirl. We introduce ... -
Two Dimensional Fiber Bundle Bridge Model
Nygård, Håkon Tormodsen (Master thesis, 2016)The two dimensional fiber bundle bridge model is introduced, derived and studied for an uniform threshold distribution. The model is independent of history and has an adjustable effective range of interaction, which is ...