Catalytic effect of submicron TiO$_2$ particles on the methane–air flames speed

A PIV study of a conical premixed methane–air Bunsen flame has shown that the inside of the cone has a complex gas-dynamic structure. In this system, the velocity of the gas flow entering the flame front varies in different parts of the flame cone and the stream tubes are not straight. The Landau–Markstein effect is discussed in the interpretation of the experimental data. A method of processing PIV measurement results is proposed that improves the accuracy of determining the burning velocity and allows a quantitative determination of the catalytic effect of submicron TiO$_2$ particles, which is proportional to the particle surface area. The relative increase in the burning velocity is 2% per each $\approx$ 0.01 cm$^2$/cm$^3$ (particle surface/gas volume) of the total specific surface area of the particles. The experimental data are well described by modeling using well-known literature data on the detailed mechanism of chemical reactions and the mechanism of catalytic oxidation of methane with oxygen on metal oxides.