Fuel/air mixing characteristics of a Micromix burner for hydrogen-rich gas turbine

Abstract

As a promising hydrogen-rich gas turbine combustion technology, Micro-mixing combustion may produce a new flame stabilization mechanism due to the novel structure. To investigate the effects of nozzle structural parameters and inlet aerodynamic parameters on mixing characteristics, this paper firstly used the background oriented schlieren technique combined with the self-development program to obtain the mixing quality, and the program was based on the optical flow method and Gladstone-Dale equation. The fuel-air mixture process was predicted by three mass diffusion models, and the Kinetic Theory model matched the experimental results best compared with the Constant Dilute Approximation model and Dilute Approximation model. The results showed that the main mixing zone moved closer to the outer wall when the premixed channel diameter increased. And the vorticity decreased with the increased premixed length, leading to a decline in mixing efficiency. For inlet aerodynamic parameters, changes in equivalence ratios only affected the shear-layer vorticity. As the combustible component of syngas was in the range of 60%–40% (by vol.), the outer wall of the premixed channel could promote fuel-air mixture. Moreover, when the equivalence ratio ranged in 0.335–0.685, the heating value of fuel varied as 4.686–7.029 and 11.715 MJ/Nm3, fuel and air were premixed uniformly near the nozzle outlet.