Active Combustion Control for a Low-Emissions Aircraft Engine Combustor Prototype: Experimental Results

DeLaat, John C.; Kopasakis, George; Saus, Joseph R.; Chang, Clarence T.; Wey, Changlie

doi:10.2514/1.b34653

Cited by 12 publications

(3 citation statements)

References 20 publications

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“…There are two classical methods for its suppression, which are the active and passive control methods [24]. Active control is typically applied by using a dynamic actuator [25]. Paschereit et al [26] applied the active control method by using an acoustic actuation on a premixed swirl-stabilized combustor.…”

Section: Introductionmentioning

confidence: 99%

Generation and Mitigation Mechanism Studies of Nonlinear Thermoacoustic Instability in a Modelled Swirling Combustor with a Heat Exchanger

2021

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In the present work, 3D Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations are performed to investigate the generation and mitigation mechanism of combustion-sustained thermoacoustic instabilities in a modelled swirl combustor. The effects of (1) swirling number SN, (2) inlet air flow rate Va and (3) inlet temperature Ti on the amplitudes and frequencies of swirling combustion-excited limit cycle oscillations are examined. It is found that the amplitude of acoustic fluctuations is increased with increasing SN and Va and decreased with the increase of Ti. The dominant frequency of oscillations is also found to increases with the increase of SN and Va. However, increasing Ti leads to the dominant frequency being decreased first and then increased. An alternative passive control method of installing an adjustable temperature heat exchanger on the combustion chamber wall is then proposed. Numerical results show that thermoacoustic oscillations could be excited and mitigated by setting the heat exchanger temperature to TH. Global and local Rayleigh indexes are applied to further reveal the excitation and attenuation effects on mechanisms. The present study is conducive to developing a simulation platform for thermoacoustic instabilities in swirling combustors. It also provides an alternative method to amplify or mitigate thermoacoustic oscillations.

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Section: Introductionmentioning

confidence: 99%

Generation and Mitigation Mechanism Studies of Nonlinear Thermoacoustic Instability in a Modelled Swirling Combustor with a Heat Exchanger

2021

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“…Thermoacoustic instabilities may be mitigated by active control or passive control [8]. Active control method are typically applied by applying a dynamic actuator such as a loudspeaker.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Nonlinear Self-sustained Thermoacoustic Instability in a Swirling Combustor

Sun

Zhao

2020

AIAA Propulsion and Energy 2020 Forum

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Self-exited thermoacoustic instability is undesirable in gas turbines and other propulsion systems due to structural vibration, overheating and flame flashback. Such instability is characterized with large-amplitude limit cycle oscillations. It is typically resulting from the dynamic interaction between turbulence flow-flame-acoustics. A better understanding on the interaction, and an alternative design of effective damping/control approach to stabilize combustors are wanted. In this work, 3D numerical simulations are conducted on a swirling combustor to gain insight on the generation of nonlinear swirling flow-flame-coupled thermoacoustic instability. To capture the turbulence flow-combustion-acoustics interaction, the classical turbulence model for swirling flow RNG k-ε and eddy dissipation concept model with 2-steps are applied. The model is validated first with the experimental data available in the literature. Then it is applied to study the effect of swirling number SN. It is found that increasing the SN leads to the amplitude of combustion instability being increased. The dominant frequency is found to shift to a higher value with increased SN. To attenuate the selfexcited thermoacoustic instability, we propose an alternative passive control approach by implementing a heat exchanger at a pre-selected segment of combustor wall; its temperature TH could be varied. Numerical results show that properly setting TH can attenuate the thermoacoustic instability by approximately 20 dB. The present study contributes to developing a platform to simulate nonlinear thermoacoustic instability in a swirling combustor. It also opens up an alternative control means to prevent the onset or attenuate the undesirable limit cycle oscillations.

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“…Previous works to study combustor thermo-acoustic instabilities have relied upon feedback signals from pressure sensors [4]. This feedback signal is now being utilized in conjunction with fuel modulating actuators to actively control the instabilities, which has led to extensive active research in this area [5,6].…”

Section: Introductionmentioning

confidence: 99%

In-Line Electromagnetic Actuator for Fuel Modulation

Okojie

Chang

Thomas

et al. 2018

2018 Joint Propulsion Conference

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An in-line electromagnetic actuator with normally-open configuration has been developed for the purpose of exploring its application as a fuel modulator for the active control of combustor thermo-acoustic instabilities. The actuator is based on the spring-coil-plunger mechanism with the plunger designed to be suspended by crossed cantilever beam springs. Operational specification was set for a 1000 psi maximum inlet fuel pressure and modulation for a broad frequency bandwidth that encompasses frequencies that are typically associated with combustor thermo-acoustic instabilities. Various test results demonstrated fuel modulation up to 1200 Hz for coil excitation voltage between 2.3 and 4.6 V and current between 16 and 48 mA, respectively. The initial goal of this work was to demonstrate fuel modulation based on the concept of a normally-open fuel modulator with tethered plunger displacement.

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Active Combustion Control for a Low-Emissions Aircraft Engine Combustor Prototype: Experimental Results

Cited by 12 publications

References 20 publications

Generation and Mitigation Mechanism Studies of Nonlinear Thermoacoustic Instability in a Modelled Swirling Combustor with a Heat Exchanger

Generation and Mitigation Mechanism Studies of Nonlinear Thermoacoustic Instability in a Modelled Swirling Combustor with a Heat Exchanger

Numerical Study of Nonlinear Self-sustained Thermoacoustic Instability in a Swirling Combustor

In-Line Electromagnetic Actuator for Fuel Modulation

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