Numerical Simulations of Methane Diffusion Flame with Burner Rotation

Abstract

Numerical simulations have been conducted to study methane diffusion flame with burner rotation. The burner rotational speed is from 300 rpm to 1200 rpm; the burner diameter is 1 cm and 2 cm; the injection velocity is 10 cm/s and 15 cm/s. Quantitative data obtained includes the velocity profile, the temperature profile, and the frequencies of fluctuation. From the simulation data, the flame shape is obtained from the temperature data and reasonably agrees with the flame shape in the experiment. Because the flame is buoyancy dominant, the frequency scales to the square root of the burner’s diameter. Vortex flow, found around the burner cylinder and induced by the burner rotation, causes the flame to be unstable at the burner exit for rotational speed larger than 800 rpm. Rotational speed increase also reduces the pulsation frequency, but not as significant as a change in burner diameter. The length of the burner cylinder and the fluctuations of the flame alter the vortex propagation shapes and directions, as well as the frequencies of the flame. It is clear that the burner length is the medium for generating instability.