Investigation of the effect of the flame holder geometry on the flame structure in non-premixed hydrogen–hydrocarbon composite fuel combustion

In this paper, the effect of the flame holder geometry on the flame structure of a mixed hydrogen–hydrocarbon fuel is numerically studied. The fuels used in this study are 100% H$_2$, 50% H$_2$ + 50% CH$_4$, and 100% CH$_4$. Numerical results obtained by using the $k$–$\varepsilon$ and $\beta$-PDF models show good agreement with experimental data. The results show that increasing both the flame holder length and hydrogen percentage in the fuel decreases the flame length. The flame temperature decreases with decreasing flame holder length. Adding hydrogen to methane increases the peak temperature of the flame and moves its location toward the burner inlet. It is observed that the dependence of the flame length as a function of the flame holder diameter has a minimum at a certain value of the latter. The flame temperature is higher for smaller flame lengths.