## 4 Results and Discussions
### Laminar Burning Velocity of Ternary Fuel Blending  
The LBV is the basic fundamental property of combustible mixtures and the key parameter in turbulent combustion. Based on the flame radius history in the large-scale combustion chamber, the S\({}_{I}\) of NH\({}_{3}\)/H\({}_{2}\)/CH\({}_{4}\) air mixtures are extracted using a non-linear approach. Figure 6 illustrates the LBV of NH\({}_{3}\)/H\({}_{2}\)/CH\({}_{4}\) air flames as a function of fuel blends at 0.1 MPa and 298 K. The left side of the figure displays the LBV of methane-hydrogen binary fuels, ranging from the 0 to 40% hydrogen fraction. It can be observed that the LBV increases non-linearly with the abscissa, showing a steeper slope for ammonia-hydrogen blends compared to ammonia-methane and methane-hydrogen blends. The minimum LBV value (for pure methane with \(X_{H_{2}}\) = 0) corresponds to the maximum LBV value for NH\({}_{3}\)/CH\({}_{4}\) air flames (for pure methane with \(X_{NH_{3}}\) = 0), and the LBV decreases non-linearly with increasing ammonia fraction. It is notable that the rapid increase in the LBV occurs after 20% hydrogen blending, when ammonia becomes the non-dominating fuel. Moreover, the impact of the 20% hydrogen addition in the ternary fuel is smaller compared to methane-ammonia flames. However, when the methane fraction exceeds 60% in the mixture with 20% hydrogen, a significant increase in LBV is observed. In order to compare the magnitude of enhancement on \(S_{l}\) due to the addition of H\({}_{2}\) and CH\({}_{4}\) to NH\({}_{3}\)/air flames, two normalized enhancement effect parameters are suggested, as follows:  
\[\Gamma_{(\gamma,\beta,\sigma,\Phi)},\%_{\phi}=\frac{S_{l,M}(\gamma,\beta,\sigma,\Phi)-S_{l,NH_{3}}(\Phi)}{S_{l,NH_{3}}(\Phi)} \tag{7}\]  
where \(S_{l,NH_{3}}(\Phi)\) is the LBV of the neat ammonia-air mixture that depends only on the equivalence ratio and \(S_{l,M}(\sigma,\beta,\gamma,\Phi)\) is the LBV of the ternary fuel-air mixture with M = (H\({}_{2}(\gamma)\), CH\({}_{4}(\sigma)\), and NH\({}_{3}(\beta)\)), as shown in Table 2, and that depends on blending ratios and the equivalence ratio. The enhancement parameter \(\Gamma\) is calculated using the present experimental data. Figure 7 displays the enhancement parameter as a function of the hydrogen blending ratio, specifically at a ratio of 40%. It is evident that hydrogen has the highest impact on enhancing the LBV of ammonia/air flames, while methane has the lowest enhancement effect, regardless of the value of \(\phi\). In the case of 40% hydrogen blending, the greatest enhancement impact is observed, with an increase of 820% compared to 550% for 0% hydrogen blending, both at \(\phi=1\). The degree of enhancement varies with blending ratios and \(\phi\), with a more pronounced effect under fuel-lean conditions compared to rich fuel conditions. Figure 6: LBV of NH\({}_{3}\)/H\({}_{2}\)/CH\({}_{4}\) air flames versus fuel blends at 0.1 MPa and 298 K.  
Figure 7: Enhancement effect on the LBV by adding 40% H\({}_{2}\) into NH\({}_{3}\)/CH\({}_{4}\)/air flames at \(\phi=0.9\)–1.2 at 0.1 MPa and 298 K.  
Two important behaviors can be observed from the results. Firstly, when operating under the same stoichiometric ratio conditions, the enhancement achieved by using ternary fuels is much more favorable compared to using dual fuels. This impact remains consistent across the tests conducted in this study. For instance, to achieve an enhancement parameter \(\Gamma\) of 500% at \(\phi=1\), the dual fuel mixture requires 90% methane and 10% ammonia, while using ternary fuels allows for achieving the same \(\Gamma\) by blending 40% hydrogen with 36% ammonia and 34% methane. This mixture resolves the emission problem associated with a large blend of methane and also mitigates NO\({}_{x}\) emissions with high ammonia blends.