Experimental Investigation of Self-Excited Combustion Instabilities in a LOX/LNG Rocket Combustor

Martin, Jan; Armbruster, Wolfgang; Hardi, Justin; Suslov, Dmitry; Oschwald, Michael

doi:10.2514/1.b38289

Cited by 8 publications

(13 citation statements)

References 19 publications

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“…In BKD tests with the propellant combination LOX/LNG, injector-coupled combustion instabilities occurred in a configuration with recess, whereas no instabilities occurred without recess. 8 In this study also evidence was presented, that depending on the injection condition both lifted and anchored flames can be present with LOX/LNG combustion.…”

Section: Varying Flame Anchoring Positions In the Injector Recesssupporting

confidence: 52%

Impact of shear-coaxial injector hydrodynamics on high-frequency combustion instabilities in a representative cryogenic rocket engine

Armbruster¹,

Hardi²,

Oschwald

2022

International Journal of Spray and Combustion Dynamics

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The excitation mechanism of a thermoacoustic instability in a 42-element research rocket thrust chamber with representative operating conditions with respect to European cryogenic rocket engines is investigated in detail. From previous research it was known that the chamber 1T mode can be excited by persistent heat release rate oscillations which are modulated by the resonant modes of the liquid oxygen injectors. The excitation source of the longitudinal injector eigenmodes is investigated in this study. Fibre-optical probes measuring the OH* dynamics from the recess volume of two injectors showed additional frequency content which could neither be explained by the chamber acoustics, nor the acoustics of the injection system. Instead, the temporal evolution of these frequencies correlate with the oxidizer flow velocity. In this work we show that the additional flame modulation originates from a hydrodynamic effect in the injection system. Even though the exact process cannot be precisely identified, an effect designated orifice whistling at the injector inlet orifice seems to be a likely candidate. Combining the new results with previous publications about this combustor, it is now possible to explain past and present observations in terms of the hydrodynamic and thermoacoustic conditions which are necessary for the combustion instability to appear. The conditions, which lead to an injection-driven excitation of the 1T mode are matching frequencies of the 2L mode of the injectors and the chamber 1T mode as well as a Strouhal number between 0.2 and 0.4 based on the length and flow velocity of the injector inlet orifice.

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Section: Varying Flame Anchoring Positions In the Injector Recesssupporting

confidence: 52%

Impact of shear-coaxial injector hydrodynamics on high-frequency combustion instabilities in a representative cryogenic rocket engine

Armbruster¹,

Hardi²,

Oschwald

2022

International Journal of Spray and Combustion Dynamics

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“…2016; Martin et al. 2021), (iii) the induction of fuel flow velocity fluctuations due to the propagation of pressure fluctuations into the fuel injector (Urbano et al. 2017), (iv) the effects of the pressure and flow velocity fluctuations on the jet flame behaviour (Morgan, Shipley & Anderson 2015) and (v) the driving of high-frequency combustion instability due to a repetition of detachment and reignition of a jet flame at the shear layer region between fuel and oxidizer flows (Harvazinski et al.…”

Section: Introductionmentioning

confidence: 99%

“…2021; Martin et al. 2021). However, in those studies, the relevance of the interesting switching phenomena between the attached and lifted flame edges from the injector to the sustainment mechanism of high-frequency combustion instability has not been investigated from the viewpoint of complex networks and machine learning.…”

Section: Introductionmentioning

confidence: 99%

“…Extensive and comprehensive reviews on the feedback mechanisms have been provided by Lieuwen & Yang (2005), Huang & Yang (2009), Lieuwen (2012) and O'Connor, Acharya & Lieuwen (2015). Many numerical and experimental investigations on high-frequency combustion instability in various model rocket engine combustors have focused on the following points related to the driving and feedback mechanisms: (i) the coupling of pressure and heat release rate fluctuations , (ii) the mutual interaction between the acoustic modes inside the combustor and the oxygen injector (Gröning et al 2016;Urbano et al 2016;Martin et al 2021), (iii) the induction of fuel flow velocity fluctuations due to the propagation of pressure fluctuations into the fuel injector , (iv) the effects of the pressure and flow velocity fluctuations on the jet flame behaviour (Morgan, Shipley & Anderson 2015) and (v) the driving of high-frequency combustion instability due to a repetition of detachment and reignition of a jet flame at the shear layer region between fuel and oxidizer flows (Harvazinski et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…As mentioned above, the formation and feedback mechanisms of high-frequency combustion instability have been examined in many experimental and numerical studies (Harvazinski et al 2015;Morgan et al 2015;Gröning et al 2016;Urbano et al 2016Armbruster et al 2021;Martin et al 2021). However, in those studies, the relevance of the interesting switching phenomena between the attached and lifted flame edges from the injector to the sustainment mechanism of high-frequency combustion instability has not been investigated from the viewpoint of complex networks and machine learning.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Complex-network analysis of high-frequency combustion instability in a model single-element rocket engine combustor

et al. 2023

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We study the spatio-temporal dynamics of high-frequency combustion instability in a model single-element rocket combustor using an acoustic energy flux-based spatial network. The acoustic energy source collapses by the formation of small communities with weak connection when the flame edge is attached to the injector rim. In contrast, large communities with strong connection are formed in the shear layer between the oxygen and hydrogen jets when the flame edge is detached from the injector rim, which has a significant impact on driving combustion instability. The switching between the attachment and detachment of the flame edge during combustion instability can be explained by the spectral-clustering-based transition network constructed from the pressure and flow velocity of the hydrogen jet at the injector exit, and the temperature near the injector rim.

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Effects of recess length on combustion instability in a model chamber with a gas-centered swirl coaxial injector

Wang

Cho

et al. 2022

Aerospace Science and Technology

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Experimental Investigation of Self-Excited Combustion Instabilities in a LOX/LNG Rocket Combustor

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Cited by 8 publications

References 19 publications

Impact of shear-coaxial injector hydrodynamics on high-frequency combustion instabilities in a representative cryogenic rocket engine

Impact of shear-coaxial injector hydrodynamics on high-frequency combustion instabilities in a representative cryogenic rocket engine

Complex-network analysis of high-frequency combustion instability in a model single-element rocket engine combustor

Effects of recess length on combustion instability in a model chamber with a gas-centered swirl coaxial injector

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