Optimal control of turbulent premixed combustion instability with annular micropore air jets

Zhou, Hao; Tao, Chunhui; Liu, Zihua; Meng, Sheng; Ke-fa, Cen

doi:10.1016/j.ast.2019.105650

Cited by 30 publications

(29 citation statements)

References 38 publications

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“…The growth rate G exp ≡ (α/ω) exp and the acoustic resonant frequency ω are confirmed by our well-design T-shaped combustion system with a cooling-flow perforated pipe implemented. The present work sheds lights on the fundamental physics and mechanisms underlying the self-excited combustion oscillations [51][52] in any hydrocarbon-fuelled combustors. The theoretical maximum growth rate is applicable to a combustion system with other types of fuels, such as Hydrogen and Ammonia.…”

Section: Discussionmentioning

confidence: 88%

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Zhao

2020

J. Therm. Sci.

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Unlike electric vehicles and electric aircrafts, hydrocarbon-fuelled (fossil) engine systems are much noisier. By conducting one-step chemical reaction-thermodynamics-acoustics coupling studies and experimental measurements, we explore the universal physics of how hydrocarbon-fuelled combustion is a noise maker. We also explain that how combustion-sustained noise at a particular frequency ω is intrinsically selected. These frequencies correspond to the acoustic resonance nature of the combustor. We find that a reacting gas in which the rate of chemical reacting increases with temperature is intrinsically and naturally unstable with respect to acoustic wave motion, since its modal growth rate α is greater than 0. Acoustic disturbances tend to exponentially i.e. exp(αt) increased first and then are limited by nonlinear effects and finally grow into limit cycle oscillations. The growth rate α is found to increase first and then decrease with the gradient of the heat release rate with respect to the temperature change, i.e. heat capacity. The maximum (α/ω) max depends on the specific heat ratio γ, which is related to the speed of sound. The unstable nature could be changed by introducing some acoustic dissipative/damping mechanism, such as the boundary layer viscous drag and boundary losses. It is shown that such losses could lead to increased critical heat capacity, below which stable combustors can be designed. Finally, the acoustical energy consisting of both potential and kinetic energy is found to grow exponentially faster by 100% than the acoustic disturbance amplitude.

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Section: Discussionmentioning

confidence: 88%

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Zhao

2020

J. Therm. Sci.

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“…This research was carried on a model gas turbine combustor, which was used for lean‐premixed combustion 19,20,29 . Figure 1 shows the detailed structure of the model gas turbine combustor.…”

Section: Methodsmentioning

confidence: 99%

“…Eliminating combustion instability with JICF around the burner nozzle has been demonstrated in the past. Previous studies 13–21 showed the application of JICF on combustion instability, which summarized various JICF methods and their control characteristics. They summarized the variation characteristics of flame–vortex interaction under different JICF.…”

Section: Introductionmentioning

confidence: 99%

“…The low‐bandwidth and high‐momentum jets could achieve a better combustion instability control effectiveness. Zhou et al 19 and Zhou and Tao 20 simultaneously eliminated thermoacoustic instabilities and NO x emissions with CO 2 /O 2 gas dilution. They proved that thermoacoustic instability and NO x emissions could be suppressed simultaneously.…”

Section: Introductionmentioning

confidence: 99%

“…The injecting momentum and density gradient of the JICF affect the responses of unsteady flame 19,20 . Because the mutual interaction of flame and JICF will lead to the formation of smaller tertiary filaments, 22 the flame anchoring zone under different molecular masses of gas has never been investigated, although there are many studies on thermoacoustic instability JICF, 12–21 such as air, hydrogen, N 2 , O 2 , and CO 2 . However, there is no research that explores the effect of relative molecular masses on combustion instability and NO x emission.…”

Section: Introductionmentioning

confidence: 99%

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Effect of carbon dioxide, argon, and helium jets on the synchronous control of combustion instability and NO_x emission

Tao

Zhou

2020

Asia-Pacific J Chem Eng

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This article experimentally studies the synchronous control of combustion instability and NOx emission in a model gas turbine combustor. The application of tabular jet in cross flow was adopted to test the effectiveness of synchronous control. The flow rate, height, direction, and relative molecular masses were studied in this research. Results suggest that the ideal damping ratio of the sound pressure amplitude can be as high as 73.7% under the carbon dioxide jet in cross flow case. The carbon dioxide jet in cross flow case can lead to a better thermoacoustic instability suppression result than the instances of argon or helium. Besides, amplitude and frequency switching of the unsteady flame emerged during the experiment. Adding minimal inert gaseous can change the local oscillation of equivalence ratio. The suppression ratio of NOx emission can reach as high as 44% under the carbon dioxide cases, which performs better than the argon or helium cases. Moreover, the flame length declines as the tabular jet in cross flow rate increases. When the flow rate increases (or the height decreases), the size of the flame front or root will decrease. The average flame length dropped from 122 to 41 mm. The macrostructure of the flame changes significantly under different injecting heights or directions. This article can serve as a specific guideline for the passive control of thermoacoustic instability in gas turbine, rocket, and industrial burners.

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Mitigating combustion instability and NO_x emissions with annular oxyfuel jets into the flame shear layer region

Tao

Zhou

2021

Asia-Pacific J Chem Eng

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The shear layer is a region between the internal and external recirculating zone of the flame, which is critical for combustion stabilization and emission. This study experimentally studied the effects of oxyfuel (CO2/O2) shear layer injections on combustion dynamics and pollutant emissions of a model gas turbine combustor. To evaluate the damping performances of ‘Oxy’ CO2/O2 shear layer jets on unsteady combustion and pollutant formation processes, four variables of the CO2/O2 shear layer injection system are studied—the flow rate, the inner diameter, the injection angle and the oxygen ratio. Experimental results show that thermoacoustic instability and NOx emissions can be suppressed with the ‘Oxy’ CO2/O2 shear layer injection method. The minimum inner diameter cases could achieve better control effectiveness of 80%, with the sound pressure amplitude drops from 27 to 5.4 Pa. The maximum inner diameter case could achieve better control effectiveness of 59.2%, with the concentration of NOx emissions drops from 25 to 10.2 ppm. Flame oscillation modes experienced shifting and switching under different shear layer angles and oxygen ratios. There exist extreme points that can be selected for a better control effect. The CO2/O2 shear layer injection splits the inner and outer recirculation zones of the flame. As the oxygen ratio of CO2/O2 varied from 36% to 46%, a flame flapping phenomenon emerged. The ‘Oxy’ CO2/O2 shear layer injection method could eliminate combustion instability and NOx emissions at a relatively lower cost and complexity, which will promote the development of high‐performance burners.

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Optimal control of turbulent premixed combustion instability with annular micropore air jets

Cited by 30 publications

References 38 publications

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Effect of carbon dioxide, argon, and helium jets on the synchronous control of combustion instability and NO_x emission

Mitigating combustion instability and NO_x emissions with annular oxyfuel jets into the flame shear layer region

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Optimal control of turbulent premixed combustion instability with annular micropore air jets

Cited by 30 publications

References 38 publications

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Thermodynamics-Acoustics Coupling Studies on Self-Excited Combustion Oscillations Maximum Growth Rate

Effect of carbon dioxide, argon, and helium jets on the synchronous control of combustion instability and NOx emission

Mitigating combustion instability and NOx emissions with annular oxyfuel jets into the flame shear layer region

Contact Info

Product

Resources

About

Effect of carbon dioxide, argon, and helium jets on the synchronous control of combustion instability and NO_x emission

Mitigating combustion instability and NO_x emissions with annular oxyfuel jets into the flame shear layer region