Simulating Full-Scale Transverse Combustion Instabilities in a Lab-scale Facility

Quinlan, John M.; Zinn, B. T.

doi:10.2514/6.2013-4019

Cited by 4 publications

(9 citation statements)

References 5 publications

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“…The speaker's electrical impedance is defined as Z el = VBEMF(t) IBEMF(t) , and is supplied by the speaker manufacturer, JBL, as a function of signal frequency. The voltage induced by the BEMF within the speaker voice-coil can be expressed as [7]:…”

Section: Figure 4: Schematic Of Speaker Mass Spring Damper Systemmentioning

confidence: 99%

“…the speaker damping coefficient, b, and spring constant, κ), a process similar to that of Quinlan et. al was carried out [7]. This process entailed developing a model that represented the speaker as a forced mass spring damper system by the speaker's voice coil.…”

Section: Speaker Constant Determinationmentioning

confidence: 99%

“…al [7]. To derive the SMFRF, the speaker diaphragm was assumed to be a harmonic mass spring damper system that has a coil force applied to the diaphragm, as well as an acoustic force from the system.…”

Section: Development Of the Speaker Model Frequency Response Functionmentioning

confidence: 99%

“…Contained within this coil force, F coil (t), is both the Lorentz force applied from the voice coil, F Lorentz (t), as well as the backward electromotive force (BEMF), F BEMF (t). The mass spring damper system was assumed to have a single degree of freedom, and is represented in Figure 4 below [7].…”

Section: Development Of the Speaker Model Frequency Response Functionmentioning

confidence: 99%

“…al in which a similar JBL speaker and diaphragm were disassembled in order to get accurate measurements [8,7], whereas d dphgm , B & Electrical Impedance can be found in the JBL 2446J specification sheet. …”

Section: Figure 5: Short Impedance Tube Test Facilitymentioning

confidence: 99%

See 4 more Smart Citations

An Analytical Investigation Characterizing the Application of Single Frequency Acoustic Modulation for High Frequency Combustion Instability Suppression

Cranford¹,

Bennewitz²,

Rani³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Section: Figure 4: Schematic Of Speaker Mass Spring Damper Systemmentioning

confidence: 99%

Section: Speaker Constant Determinationmentioning

confidence: 99%

Section: Development Of the Speaker Model Frequency Response Functionmentioning

confidence: 99%

Section: Development Of the Speaker Model Frequency Response Functionmentioning

confidence: 99%

Section: Figure 5: Short Impedance Tube Test Facilitymentioning

confidence: 99%

See 3 more Smart Citations

An Analytical Investigation Characterizing the Application of Single Frequency Acoustic Modulation for High Frequency Combustion Instability Suppression

Cranford¹,

Bennewitz²,

Rani³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

View full text Add to dashboard Cite

Combustion Instability Control Through Acoustic Modulation at the Inlet Boundary: Analysis

Bennewitz

Rani

Cranford

et al. 2015

Journal of Propulsion and Power

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A linear modal analysis is undertaken to investigate the effects of acoustic modulation at the inlet boundary on the longitudinal instability modes of a dump combustor. This study complements an accompanying experimental investigation that demonstrates combustion instability control through single-frequency acoustic modulation at the inlet [Bennewitz, J. W., Frederick, R. A., Jr., Cranford, J. T., Lineberry, D. M., "Combustion Instability Control Through Acoustic Modulation at the Inlet Boundary: Experiments," Journal of Propulsion and Power (to be published)]. The modal analysis employs acoustically consistent matching conditions instead of the conventional mass, momentum, and energy balances. A specific impedance boundary condition at the inlet is derived through a mass-spring-damper model of a speaker diaphragm that provides the acoustic modulation. The speaker model constants are obtained from an apparatus consisting of a speaker attached to a short hard-wall-terminated duct. At first, the modal analysis is shown to predict a naturally unstable first longitudinal mode in the absence of acoustic modulation, consistent with the spontaneously excited combustion instability mode observed experimentally. Subsequently, a detailed investigation involving variation of the modulation frequency from 0 to 2500 Hz and a mean combustor temperature from 1248 to 1685 K demonstrates the unstable to stable transition of a 2300-2500 Hz first longitudinal mode. The model-predicted mode stability transition is consistent with experimental observations, thereby supporting the premise that inlet acoustic modulation is a means to control high-frequency combustion instabilities. From the modal analysis, it may be deduced that the inlet impedance provides a damping mechanism for instability suppression. Nomenclature A = speaker diaphragm area, m 2 A = amplitudes of the longitudinal mode propagating in the positive and negative x directions, Pa B = electromagnetic speaker B field, T b = speaker diaphragm damping coefficient, N · s∕m c = mean sound speed, m∕s d dphgm = diaphragm diameter, cm F = force, N f acous;sys = acoustic system resonant frequency of the speaker constant determination test facility, Hz f mech;spk = mechanical resonance of the speaker, Hz G amp = amplifier gain Hf = speaker model frequency response function, m∕s · A I = current, A k = axial wave numbers of the longitudinal mode propagating in the positive and negative x directions, 1∕m L const;sys = length of the speaker constant determination test facility, cm M = mean flow Mach number m = speaker diaphragm mass, kg N = number of speaker diaphragm voice coil turns p 0 spk = acoustic pressure at the speaker diaphragm, Pa p 0 = acoustic pressure fluctuations, Pa p= mean pressure, Pa T comb = average combustor temperature measured from the four thermocouples located within the chamber, K u 0 spk = acoustic velocity at the speaker diaphragm, m∕s u 0 = acoustic velocity fluctuations, m∕s u = mean velocity, m∕s Z = impedance, Pa · m∕s β = region index κ = speaker diaphr...

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Injector-Driven Combustion Instabilities in a Hydrogen/Oxygen Rocket Combustor

Gröning

Hardi

Suslov

et al. 2016

Journal of Propulsion and Power

107

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Simulating Full-Scale Transverse Combustion Instabilities in a Lab-scale Facility

Cited by 4 publications

References 5 publications

An Analytical Investigation Characterizing the Application of Single Frequency Acoustic Modulation for High Frequency Combustion Instability Suppression

An Analytical Investigation Characterizing the Application of Single Frequency Acoustic Modulation for High Frequency Combustion Instability Suppression

Combustion Instability Control Through Acoustic Modulation at the Inlet Boundary: Analysis

Injector-Driven Combustion Instabilities in a Hydrogen/Oxygen Rocket Combustor

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