Model for Acoustic Induced Aluminum Combustion Fluctuations in Solid Rocket Motors

Genot, Aurélien; Gallier, Stany; Schuller, Thierry

doi:10.2514/1.b37437

Cited by 14 publications

(35 citation statements)

References 50 publications

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“…7 it is reported the Rayleigh index integrated over the whole volume as function of time for one oscillation period. Notwithstanding the fluctuating behaviour it is easily proved that the time integral leads to an overall positive value: this definitely proves that the motor analyzed is prone to experience an instability via thermoacoustic coupling, matching the results presented in the reference works [19,22].…”

Section: Time Ssupporting

confidence: 78%

“…This process inevitably produces vorticity, which is then convected downstream and dissipated by viscous effects. A consequence of such behaviour is represented by the intensification of velocity oscillations standing in the acoustic boundary layer with regard to the ones in regions far from the surface [19,22,45]. This last feature is also well recovered by the CFD solution hitherto presented as clearly visible in Fig.…”

Section: A Numerical Resultsmentioning

confidence: 54%

“…The same SRM geometry presented in Gallier et al [19] and Genot et al [22] has been employed as test case since its tendency to be prone to thermoacoustic instability. The motor has a simple cylinder grain shape and it is short enough to prevent PVS [41].…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…From such interaction arises the possibility of a pure thermoacoustic feedback loop: an acoustic disturbance triggers a combustion rate increasing which, in turn, enhances flow instability. Anyway, despite convection effects are known since first works on aluminum combustion [16,17], the onset of a thermoacoustic coupling involving an oscillatory gaseous field and particles combustion has been firstly addressed by Raun and Beckstead in 1993 [18] and then very recently studied and analyzed in French literature [19][20][21][22][23]. Nevertheless the way aluminum droplet combustion couples with the acoustic field remains not fully understood and the research about this topic represents an ongoing challenge especially when other kinds of instability sources can be meanwhile present.…”

Section: Introductionmentioning

confidence: 99%

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Modeling Multiphase Effects on Pressure Oscillations in Solid Propulsion

Grossi

Bianchi

Favini

2020

AIAA Propulsion and Energy 2020 Forum

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In this work multiphase effects on pressure oscillations within solid rocket motors are addressed with particular focus on thermoacoustics. A mathematical and numerical approach is described and implemented in an already existing CFD in-house code, taking care of employing the most simplified physical describing tool suite. In order to validate such methodology, numerical simulations have been performed on simplified geometries known in literature to be prone to develop pressure fluctuations due multiphase effects. The presented solutions show actually an instable behaviour, whose thermoacoustic nature is proved by the presence of its characteristics key features and by Rayleigh criterion analysis. Such result ensures the model validation, which is the preliminary and obligatory step of a work-in-progress project aimed to improve the understanding about pressure oscillations in solid rocket motors.

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Section: Time Ssupporting

confidence: 78%

Section: A Numerical Resultsmentioning

confidence: 54%

Section: Numerical Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling Multiphase Effects on Pressure Oscillations in Solid Propulsion

Grossi

Bianchi

Favini

2020

AIAA Propulsion and Energy 2020 Forum

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“…In the field of solid rockets, oxide residues in the combustion chamber can significantly contribute to two-phase performance losses when ejected through the nozzle [8]. Recent studies have also pointed out that burning of aluminum could trigger thermoacoustic instabilities in solid rocket motors [9,10] and that the size of this oxide residue could play a significant role [11].…”

Section: Introductionmentioning

confidence: 99%

The role of thermophoresis on aluminum oxide lobe formation

Gallier

Braconnier

Godfroy

et al. 2021

Combustion and Flame

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This work studies the influence of phoretic motion (thermophoresis and diffusiophoresis) of fine alumina particles ("smoke") produced during the combustion of aluminum. Direct numerical simulations on a single aluminum droplet burning in a quiescent environment suggest that thermophoresis is the main mechanism driving smoke back to the aluminum surface, hence a major contributor to the oxide lobe development. The presence of this lobe is found to distort the flowfield, which favors hot and smoke-rich regions closer to the lobe, thereby enhancing thermophoresis. This combination of aerodynamic and thermophoretic effects leads to a mass rate of deposited smoke which is consistent with experimental data. A simplified model, deduced from simulation results, is able to predict the size of the final oxide residue in good agreement with measurements. This study supports that aluminum oxide present on the burning aluminum particle is largely due to material formed in the flame, subsequently desposited by thermophoresis.

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