Application of The Chain Code and Fourier Analysis Techniques for The Investigation of Wrinkles and Distortions on Early Flames

  • Abd Rashid Abd Aziz Center for Automotive Research and Electric Mobility (CAREM), Universiti Teknologi Petronas, 31750 Tronoh, Perak, Malaysia
  • Ftwi Yohaness Hagos Advanced Fluids Focus Group (AFFG), Faculty of Mechanical Engineering, Universiti Malaysia Pahang, 26600, Pekan, Pahang, Malaysia
  • Yohannes T Anbese Center for Automotive Research and Electric Mobility (CAREM), Universiti Teknologi Petronas, 31750 Tronoh, Perak, Malaysia
  • Morgan R Heikal School of Computing, Engineering and Mathematics, University of Brighton
  • Firmansyah Firmansyah Center for Automotive Research and Electric Mobility (CAREM), Universiti Teknologi Petronas, 31750 Tronoh, Perak, Malaysia
Keywords: Chain code; elliptic Fourier analysis; image processing; wrinkles; early flame.

Abstract

The study of flame commencement and growth in SI engine has attracted the attention of many researchers due to its strong dependence to the in-cylinder flow and its capability to influence flame propagation characteristics in SI engines. Optical visualisation has been one of the prominent techniques utilized in this study of the early flame properties. This work shows the application of Elliptic Fourier analysis (EFA) and image processing tools for the investigation of the early flame details from its shape features. An endoscopic ICCD camera was used to capture the flame images, at an interval of 2° CA starting from ignition onset for a period of 30° CAs (about 3 ms), from a CNG DI single cylinder SI engine operation in stratified and homogeneous charge conditions. The intake configuration was adjusted to acquire tumble or swirl induction, and engine speed was made to vary between 1500 and 2100 rpm. The sequences of collected images were processed to investigate wrinkles, distortion and growth rate of the early flame within the 3 ms combustion duration. Some tools of image processing, such as intensity enhancement, filtering, thresholding and boundary tracing, were applied. Once the flame boundary identified, it was chain coded, and elliptic Fourier function was utilised to characterise the contour. For this purpose, a computer programming code was proposed by the authors for automatic processing of the flame image data. The application of the elliptic Fourier analysis was found useful in the investigation of the early flame characteristics from its shape features; led to the portrayal of wrinkles and distortion levels quantitatively in a simpler way.

Published
2018-12-24
How to Cite
Abd Aziz, A. R., Hagos, F., Anbese, Y., Heikal, M., & Firmansyah, F. (2018). Application of The Chain Code and Fourier Analysis Techniques for The Investigation of Wrinkles and Distortions on Early Flames. International Journal of Automotive and Mechanical Engineering, 15(4), 5709-5728. https://doi.org/10.15282/ijame.15.4.2018.1.0438