Effects of swirl blade angle on non-premixed flame stability in radial fuel flow burners.

This study aims to visualize the non-premixed flames in a radial flow burner equipped with swirl vanes and to analyze the stability of flames. The study was carried out using concentric pipes, an air pipe 2 inch in diameter and a fuel pipe 6 mm in diameter. Fuel was injected through 3 holes with diameter of 1.5 mm. The fuel used is LPG and the air is supplied from a blower with a speed range of 3.8-6.6 m/s. The air passed a swirl vane with angles Ø=10°, 30°, 50°. The stability limits of the flame at fixed air velocities were obtained by increasing the fuel velocity until the flame blowed out. The fuel velocity were then plotted into a flame stability diagram. Furthermore, structures of the flame were visualized from ignition until the flame blows out using video camera with 240 fps. The results show that in general larger angle of the swirl vane increases levels of flame stability. At relatively low air speeds, the swirl with Ø=50° shows the broadest stability limits compared to Ø=10° and 30°. While at higher air velocity the stable flame area of the swirl with Ø=50° is narrower compared to Ø=30°. At the blade angle Ø=10° and Ø=30 ° increase in air velocity causes an expansion in flame stability, whereas at Ø=50° increase in air velocity causes a decrease in flame stability. [ABSTRACT FROM AUTHOR]