Study on threshold selection method of continuous flame images of spray combustion in the low-pressure chamber

Xie, Kai; Cui, Yunjing; Wang, Chunlin; Chen, Gan; Wang, Guanqin; Qiu, Xingqi; Wang, Jianxin

doi:10.1016/j.csite.2021.101195

Cited by 20 publications

(4 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Threshold segmentation of pictures from photography and high-speed video recordings is a cheap and efficient way to obtain flame characteristics. Several relevant studies to obtain flame characteristics from image processing can be found in [4][5][6][7][8][9][10][11][12], which are generally based on the intermittency distribution approach. The flame height and lift-off of propane turbulent jet diffusion flames attenuated by carbon dioxide at ambient temperature and pressure were studied by Tao et al [9].…”

Section: Introductionmentioning

confidence: 99%

Properties of turbulent non-premixed methane/air flames in a miniature-scale swirl burner under different coaxial airflow swirl numbers

Sheykhbaglou¹

2023

fuen

View full text Add to dashboard Cite

This study investigates the dynamics and properties of non-premixed methane/air flames under three swirl numbers by segmenting flame images using the Otsu thresholding technique. Under three operating conditions, the lean blow out (LBO) and flame length, lift-off height, maximum width, flame angle, and flame pulsing displacements in terms of flame center of gravity, length, and width are measured and compared. A high-speed camera is used to record video of flames, and the image processing of frames collected from a high-speed video was accomplished by using the intermittency distribution method to quantitatively compare flame attributes. The findings show that increasing the swirl number from 0.5 to 0.7 generally has an unfavorable effect on the LBO at given fuel flow rates, and the LBO of flames under 35° (0.6 swirl number) and 40° (0.7 swirl number) swirlers has decreased up to about 15% and 40%, respectively when compared with a 30° swirler (0.5 swirl number). Additionally, observations indicate that the flame length (𝐿) and lift-off height (𝐿𝑂) drop as the swirl number rises, although the flame width (𝑊) and angle (𝛼) show an ascending tendency. Besides, flame lift-off reveals an increasing-decreasing trend with an increment in the airflow, and flame length decreases as the airflow rate increases. It was also observed that flame pulsating displacements in terms of center of gravity (𝛿𝐶𝐺), length (𝛿𝐿), and width (𝛿𝑊) increases with an increase in the fuel flow rate, and as the swirl number is increased, 𝛿𝐶𝐺 and 𝛿𝐿 lessens, while 𝛿𝑊 increases.

show abstract

Section: Introductionmentioning

confidence: 99%

Properties of turbulent non-premixed methane/air flames in a miniature-scale swirl burner under different coaxial airflow swirl numbers

Sheykhbaglou¹

2023

fuen

View full text Add to dashboard Cite

show abstract

“…Image processing of photos obtained from photography and high-speed video recordings is an effective method to investigate the flame characteristics. Some related works to calculate flame shape from image processing can be found in [21][22][23][24][25][26][27][28] The examined literature indicates that the effects of low and high swirl of coaxial air and fuel type on the combustion and flame characteristics of a miniature-scale swirl burner have not been examined. So, in this study, a series of experiments were conducted to study the effect of swirl strength of coaxial airstream on the blow-out limits, flame lift-off height, length, width, as well as NO x and CO emissions under methane/air and n-butane/air non-premixed flames.…”

Section: Introductionmentioning

confidence: 99%

Effects of coaxial airflow swirl number on combustion and flame characteristics of methane/air and n-butane/air flames in a miniature-scale swirl burner

Sheykhbaglou¹,

Robati²

2022

Eng. Res. Express

View full text Add to dashboard Cite

In this paper, the effects of coaxial airflow swirl number on blow-out limit, flame characteristics, and emission performance of non-premixed methane/air and n-butane/air flames in a miniature-scale swirl burner are investigated experimentally. Swirl numbers ranging from 0 to 0.72 have been chosen to be examined. It was observed that increasing the vane angle does not increase the blow-out limit monotonically and a swirler with 30° vane angle (0.50 swirl number) results in the greatest blow-out limit. Besides, it was found out that methane outperforms n-butane in the blow-out limit at the same fuel flow rates. The intermittency distribution approach was used to determine flame properties such as lift-off height, length, and width. It was found that the lift-off variation with coaxial airflow Reynolds number at the specified fuel flow rates yields an inverted V-shape for Sn ≥0.50. The tip of these plots indicates the airflow rate at which the swirl shows its influence, and after this point, the lift-off height begins to decrease. It was also observed that the airflow related to this point decreases with an increase in the swirl number at a certain fuel flow rate. Furthermore, the results revealed that at high airflow rates, the flame width rises as the swirl number increases. Also, raising the swirl number and airflow Reynolds number reduced the flame length. It was also observed that n-butane/air flames have longer and wider flames than methane/air flames. Additionally, adding swirl to the airflow rate typically reduces NOx and CO concentrations and n-butane/air flames exhibit lower levels of NOx and higher levels of CO than methane/air flames under the same operating conditions.

show abstract

“…Previous works that applied optical analysis of flame propagation images resorted to binarization techniques, 6 Otsu’s thresholding method 7,8 and the use of manual image preprocessing, such as contrast, intensity, and cropping. 9,10 A study on the selection of the optimal threshold value for flame image binarization was presented in Xie et al, 11 where the authors compared the two-peak, minimum error and Otsu’s methods and the shortcomings of global bimodal methods were highlighted. An optically-accessible Diesel engine was used in Groendyk and Rothamer 12 for the analysis of fuels derived from plant oils.…”

Section: Introductionmentioning

confidence: 99%

Deep learning based techniques for flame identification in optical engines

Rufino

Coraça

Lacava

et al. 2022

International Journal of Engine Research

View full text Add to dashboard Cite

The mandatory migration from fossil to renewable energy sources requires the characterization of new alternative fuels. One important step in fuel characterization is the test in optical engines, which allows the morphological characterization of flames. This analysis requires the post treatment of images by using segmentation. In many cases, an automatic threshold presents shortcomings as the flames may present different regions with variable luminosity, as also reflections from valves and cylinder liner. Consequently, a time-consuming manual image processing is required and, therefore, an automatic procedure would be welcome. The use of deep learning techniques for image segmentation is a promising alternative for such task, which has showed excellent results in several applications. In this study, two different models were trained to identify flames in images obtained from an optical engine operating at various conditions. The dataset used to train the models was generated by using images from tests with several types of fuels and combustion modes. The effects of image resolution and the generalization capabilities for different fuels and combustion operation were investigated. After analyzing the results, the use of deep learning methods to identify and characterize flames was validated as a mean for improving processing time.

show abstract

Study on threshold selection method of continuous flame images of spray combustion in the low-pressure chamber

Cited by 20 publications

References 24 publications

Properties of turbulent non-premixed methane/air flames in a miniature-scale swirl burner under different coaxial airflow swirl numbers

Properties of turbulent non-premixed methane/air flames in a miniature-scale swirl burner under different coaxial airflow swirl numbers

Effects of coaxial airflow swirl number on combustion and flame characteristics of methane/air and n-butane/air flames in a miniature-scale swirl burner

Deep learning based techniques for flame identification in optical engines

Contact Info

Product

Resources

About