Precise measurement and prediction of flame speed and laminar burning velocity are essential for premixed combustion properties characterization, turbulent combustion models validation, progress, and validation of chemical kinetic models. Besides, the problem of lack of fossil fuel, planet pollution, and production of several fuel alternatives led researchers to reexamine the process of combustion and optimize fuel consumption. So, it would be necessary to know the change of laminar burning velocity and flame speed with thermodynamic conditions to understand the impression of practical applications in all combustion systems as working pressures and temperatures are extensively higher than the atmospheric conditions. Several investigations work regarding flame speed and laminar burning velocity had been achieved. However, a detailed literature review of methods and techniques used to measure these two parameters and the effect of operating factors for different fuels focusing on biofuels is presented in this paper for ease of reviewing.

Variations in methane–ammonia blends with hydrogen enrichment can modify premixed flame behavior and play a crucial role in achieving ultra-low carbon emissions and sustainable energy consumption. Current combustion units may co-fire ammonia/methane/hydrogen, necessitating further investigation into flame characteristics to understand the behavior of multi-component fuels. This research aims to explore the potential of replacing natural gas with ammonia while making only minor adjustments to equipment and processes. The laminar burning velocity (LBV) of binary blends, such as ammonia–methane, ammonia–hydrogen, and hydrogen–methane–air mixtures, was investigated at an equivalence ratio of 0.8–1.2, within a constant volume combustion chamber at a pressure of 0.1 MPa and temperature of 298 K. Additionally, tertiary fuels were examined with varying hydrogen blending ratios ranging from 0% to 40%. The results show that the laminar burning velocity (LBV) increases as the hydrogen fraction increases for all mixtures, while methane increases the LBV during blending with ammonia. Hydrogen-ammonia blends are the most effective mixture for increasing LBV non-linearly. Enhancement parameters demonstrate the effect of ternary fuel, which behaves similarly to equivalent methane in terms of adiabatic flame temperature and LBV achieved at 40% hydrogen. Experimental data for neat and binary mixtures were validated by different kinetics models, which also showed good consistency. The ternary fuel mixtures were also validated with these models. The Li model may qualitatively predict well for ammonia-dominated fuel. The Shrestha model may overestimate results on the rich side due to the incomplete N2Hisub-mechanism, while lean and stoichiometric conditions have better predictions. The Okafor model is always overestimated.

The unstretched flame speed of the premixed propane-methanol/ air flames has been studied experimentally in a constant volume combustion chamber with central ignition. The experiments were done at atmospheric pressure and stoichiometric air/fuel ratio. Various blending ratios of methanol (0%, 20%, 40%, 60%, 80%, 100%) by volume, and different elevated initial temperatures (348 K, 373 K, and 398 K) were used in this study. In general, the results indicated that the unstretched flame speed increased with increasing both methanol blending ratio and initial temperature. For M60 the increment value of unstretched flame speed at Ti=398K was about 9% compared with that of pure propane and by elevating the initial temperature for the same blend ratio (M60) from 348 K to 398 K the increment value was about 8.8%. It is also noticed that Markstein length decreased with increasing both initial temperature and blending ratio, which is indicate that flame instability increased with increasing these parameters.