Dilution effects of CO2, Ar, N2 and He microjets on the combustion dynamic and emission characteristics of unsteady premixed flame

Tao, Chunhui; Zhou, Hao

doi:10.1016/j.ast.2021.106537

Cited by 17 publications

(18 citation statements)

References 54 publications

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“…The acoustic-heat release interaction mechanism is limited under CO 2 upstream microjets. 31 The heat release frequency shifts to a lower frequency as the CO 2 microjets flow rate increases. In Figure 7c, the CH* frequency suppression ratio reached the maximum value of 14.4% in 3-125 case, which drops from 274.5 Hz before control to 235.1 Hz.…”

Section: Parameter Valuementioning

confidence: 98%

“…In addition, according to the geometric dimensions of the burner in Table 1, the cut-off frequency f c of the unsteady model combustor is about 1258 Hz. 31 Therefore, the sound waves in the pipe section propagate in one dimension. The thermal power P and global equivalence ratio Φ g were kept at 3.8 kW and 0.71, respectively, during the upstream microjets experiments.…”

Section: Geometric Of the Upstream Microjets Combustormentioning

confidence: 99%

“…In terms of experiments, researches on CO 2 dilution can be found in papers. [25][26][27][28][29][30][31][32] Lee et al 25 compared the dilution effects of N 2 , CO 2 , and steam on the combustion performance of H 2 -CO flame. Their results indicated 40% dilution of N 2 , CO 2 , and steam could decrease NOx by 79%, 88%, and 95%, respectively.…”

mentioning

confidence: 99%

“…In terms of instability control, CO 2 can effectively inhibit cellular instability 29 and combustion instability. 30,31 In addition to CO 2 dilution, researchers have also researched other gas dilutions. Liu et al 33 compared the effects of flame temperature controlled by Ar, N 2 , and CO 2 dilution on the polycyclic aromatic hydrocarbons (PAHs) and soot formation in partially premixed and diffusion flames.…”

mentioning

confidence: 99%

“…Although there is a lot of research on the injection method to suppress combustion instability and NOx emissions, [11][12][13][14][15]30,31 to date, there is no research on the suppression of thermoacoustic instability and NOx emissions of unsteady swirl premixed flame with upstream microjets. In addition, most jet control methods are mainly based on modifying the combustion chamber structure, which may significantly limit the combustor's operating performance and combustion efficiency.…”

mentioning

confidence: 99%

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Suppression of thermoacoustic instability and NOx emissions of unsteady swirl premixed flame with upstream microjets

Zhou

2022

Asia-Pacific J Chem Eng

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Passive control methods are widely used in unsteady combustion systems due to their robustness and convenience. This paper used the upstream microjets method for the first time to control thermoacoustic instability and pollutant NOx emissions in unsteady swirl premixed flame. Three variables of CO 2 microjets flow rate, upstream microjets distance, and microjets number are investigated. Results demonstrate the upstream microjets distance plays a significant role in restraining the thermoacoustic instability and NOx emissions. The smaller the upstream microjets distance, the more completely the thermoacoustic instability is suppressed while the NOx emissions are the opposite, which means a compromise choice needs to be made between them. The damping ratio of pressure amplitude in the chamber can reach the maximum of 81.3%, and the damping ratio of CH* intensity can reach the maximum of 80.2%. Besides, the frequency of pressure and CH* will transit to a lower mode. NOx emissions can realize a maximum reduction of 12.2 ppm. Meanwhile, the flame mode switches from an enlarged Mode-A flame to a shrunk Mode-B flame, and the flame length shows a maximum reduction of 14 mm at the largest upstream distance. However, the specific control mechanism under upstream microjets still needs further study to clarify. This research proved the feasibility of suppressing combustion instability and NOx emissions with upstream microjets in unsteady swirl premixed flame, promoting its practical application in gas turbine systems.flame mode, NO x emissions, thermoacoustic instability, unsteady swirl premixed flame, upstream microjets | INTRODUCTIONAs a complex multidisciplinary problem, combustion instability was first proposed by scholar Rayleigh. 1 When combustion instability occurs, it is often accompanied by periodic large pressure oscillations. 2,3 The power engines in gas turbines, industrial furnaces, and rockets will face the threat of damage or even failure.To prevent the occurrence of combustion instability, researchers often implement control strategies from the two necessary factors of combustion instability, namely, acoustic oscillations and heat release oscillations. For

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Section: Parameter Valuementioning

confidence: 98%

Section: Geometric Of the Upstream Microjets Combustormentioning

confidence: 99%