In thermal cutting process, gas flow injected from the nozzle has a significant effect on the cutting materials. The gas flow is difficult to observe gases are transparent, therefore, in this study, Schlieren method was adopted to visualize the gas flow inside the kerf. The kerf shape was inserted between two slices of transparent glass in order to imitate the real cutting environment. In order to get the flow characteristics, a high speed camera was equipped and the image processing was applied to compare the before and after injection images. As a result, the method for visualizing gas flow was successfully developed and also expected to be applied to the analysis of purging gas in various welding environments.

• Dae-Won Cho(Busan Machinery Research Center, Korea Institute of Machinery and Materials, 48, Mieumsandan 5-ro 41beon-gil, Gangseo-gu, Busan) Corresponding author
• Upendra Tuladhar(Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan)
• Sang-Hyun Ahn(Busan Machinery Research Center, Korea Institute of Machinery and Materials, 48, Mieumsandan 5-ro 41beon-gil, Gangseo-gu, Busan, Pukyong National University, 45, Yongso-ro, Nam-gu, Busan)
• Dae-Hwan Kim(Busan Machinery Research Center, Korea Institute of Machinery and Materials, 48, Mieumsandan 5-ro 41beon-gil, Gangseo-gu, Busan)
• Seokyoung Ahn(Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan)
• Seonmin Kim(Busan Machinery Research Center, Korea Institute of Machinery and Materials, 48, Mieumsandan 5-ro 41beon-gil, Gangseo-gu, Busan)
• Seung-Hoon Bae(Busan Machinery Research Center, Korea Institute of Machinery and Materials, 48, Mieumsandan 5-ro 41beon-gil, Gangseo-gu, Busan)
• Tae-Kook Park(Busan Machinery Research Center, Korea Institute of Machinery and Materials, 48, Mieumsandan 5-ro 41beon-gil, Gangseo-gu, Busan)