Combustion response of a LOX/LCH4 element to transverse instabilities

Wierman, Matthew; Nugent, Nicholas; Anderson, William A.

doi:10.2514/6.2011-5549

Cited by 14 publications

(11 citation statements)

References 3 publications

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“…Results from similar investigations of transverse mode influence on coaxial injection, for example by Wierman et al 18 , Pomeroy et al 17 , or Sliphorst 8 , suggest that convective transverse motion also prevented isolated extraction of combustion intensity response in those cases. Maximum response amplitudes were observed in the outer lobe regions of single flames, where the transverse motion caused alternating presence and absence of combustion.…”

Section: A Response To Excitation Of the 1t Modementioning

confidence: 88%

“…Image processing techniques were applied in an attempt to compensate for turbulence and convective motion, and to extract information about local emission intensity fluctuation in the flame. The intention to compensate for convective motion by tracking regions of intensity fluctuation has independently been declared by Wierman et al 18 .…”

Section: Compensation For Convective Motionmentioning

confidence: 98%

“…High-speed backlit shadowgraph and CH* emission imagery were recorded simultaneously to study combustion emission distribution and phase. Wierman et al 18 studied a swirl coaxial element with LOx and liquid methane, although the addition of the element resulted in noticeable damping of the 1T mode; presumably due to the drag imparted on the acoustic gas motion by the injected liquid spray.…”

Section: Introductionmentioning

confidence: 98%

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Coupling Behaviour of LOx/H2 Flames to Longitudinal and Transverse Acoustic Instabilities

Hardi¹,

Beinke²,

Oschwald³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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A rectangular combustor with acoustic forcing was used to study flame-acoustic interaction under injection conditions which are representative of industrial rocket engines. Hot-fire tests using liquid oxygen and gaseous hydrogen were conducted at pressures of 40 and 60 bar, which are sub-and supercritical conditions respectively for oxygen. To our knowledge, acoustic forcing has never before been conducted at pressures this high in an oxygen-hydrogen system. Examined samples of hydroxyl-radical emission imaging, collected using a high-speed camera during periods of forced acoustic resonance, show significant response in the multi-injection element flame. Transverse acoustic velocity causes shortening of the flame, concentrating heat release near the injection plane. Fluctuating acoustic pressure causes in-phase fluctuation of the emission intensity. Based on these observations, a theorized flame-acoustic coupling mechanism is offered as an explanation for how naturally occurring high frequency combustion instabilities are sustained in real rocket engines. Nomenclature c = bulk sound speed in combustion chamber I = OH* emission intensity I' = fluctuating component of OH* emission intensity Ī = time averaged OH* emission intensity J = injection momentum flux ratio N = response factor ω = acoustic frequency p' = acoustic pressure amplitude P cc = combustion chamber pressure p 0 = eigenmode solution acoustic pressure distribution R = Rayleigh index ROF = oxidizer-to-fuel mixture ratio ρ = bulk density in combustion chamber u' = acoustic (particle) velocity VR = injection velocity ratio

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Section: A Response To Excitation Of the 1t Modementioning

confidence: 88%

Section: Compensation For Convective Motionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

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Coupling Behaviour of LOx/H2 Flames to Longitudinal and Transverse Acoustic Instabilities

Hardi¹,

Beinke²,

Oschwald³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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show abstract

“…3 Graduate Student, Student Member AIAA. 4 Graduate Student, Student Member AIAA. 5 Professor, Associate Fellow AIAA.…”

Section: Introductionmentioning

confidence: 98%

“…current methodology, this shall provide measured response functions to validate high order simulations and to serve as input to lower order predictive models. Present experimental work at Purdue uses high-speed imaging of filtered combustion light intensity as an indicator of local heat release [4]. These movies show the line-of-sight light emission of a combusting flowfield.…”

Section: Introductionmentioning

confidence: 99%

Application of Proper Orthogonal Decomposition to Light Intensity Measurements of Combustion Instability

Wierman¹,

Pomeroy²,

Feldman³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Proper Orthogonal Decomposition (POD) has been implemented in processing of highspeed movies of combustion light emission from two combustion instability experiments. Using the method of singular value decomposition, analysis produces a series of POD modes -orthogonal bases of linked spatial and temporal modes which are sorted based on decreasing singular value or "energy," which indicates the variation and descriptivity contained within each POD mode. Without initially specified conditions or functional forms beyond raw data, the POD modes identify the measured frequencies of the chamber acoustic modes and show the physical behavior of the light emission associated with each POD mode. The major behaviors of the combustion light emission can be reconstructed using select POD modes, serving as an effective low-order approximation of high-order data. Based on this effectiveness, POD analysis shall be extended to the determination of flame describing functions from the temporal POD modes and measured pressure signals. Nomenclature= M-term approximation = temporal POD mode component = spatial POD mode component = singular value or "energy" of POD mode = number of POD modes used in approximation

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Coupling of Cryogenic Oxygen–Hydrogen Flames to Longitudinal and Transverse Acoustic Instabilities

Hardi

Beinke

Oschwald

et al. 2014

Journal of Propulsion and Power

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Combustion response of a LOX/LCH4 element to transverse instabilities

Cited by 14 publications

References 3 publications

Coupling Behaviour of LOx/H2 Flames to Longitudinal and Transverse Acoustic Instabilities

Coupling Behaviour of LOx/H2 Flames to Longitudinal and Transverse Acoustic Instabilities

Application of Proper Orthogonal Decomposition to Light Intensity Measurements of Combustion Instability

Coupling of Cryogenic Oxygen–Hydrogen Flames to Longitudinal and Transverse Acoustic Instabilities

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