## 3 Results and Discussion
The interaction of flow field between the four swirlers is also important. The interaction of flow field between the four swirlers is also important. The interaction of flow field between the four swirlers is also important. The interaction of flow field between the four swirlers is also important. The interaction of flow field between the four swirlers is also important. The interaction of flow field between the four swirlers is important. \(Y=81.28\) mm of four-point LDI combustors, the turbulence kinetic energy contours of the co-swirling four-point LDI combustor and the count-swirling four-point LDI combustor begin to be uniform and the turbulence kinetic energy also decreases. When at \(Y=101.6\) mm of four-point LDI combustors, the turbulence kinetic energy is further weakened and tending toward uniformity. The turbulence kinetic energies of the co-swirling four-point LDI combustor and the count-swirling four-point LDI combustor are completely uniform. The different swirler arrangements for the four-point LDI combustors would result in there being different distributions of turbulence kinetic energy. This would affect the fuel-air distributions of the primary combustion zone to induce the temperature difference, which is a disadvantage for reducing the NO emission. Figure 6: _Cont._  
Figure 7 shows the pressure drop coefficients of co-swirling and count-swirling four-point LDI combustors with different equivalence ratios. With the equivalence ratio increasing, the static temperature in the combustion chamber would also be increased, which results in increased velocity, which in turn, increases the total pressure loss. In other words, the pressure drop coefficients of co-swirling and count-swirling four-point LDI combustors are different with different equivalence ratio. The total temperature profiles of co-swirling and count-swirling four-point LDI combustors with different equivalence ratios are shown in Figure 8. The total temperatures of co-swirling and count-swirling four-point LDI combustors with different equivalence ratios are identical to the theoretical equilibrium temperature. This tendency verified the validation of the numerical methods and codes. When the equivalence ratio is from 0.3 to 1.0, the total temperature increases in the co-swirling and count-swirling four-point LDI combustors, with the increasing of the equivalence ratio. The temperatures of co-swirling and count-swirling four-point LDI combustors increase at approximately same rate. When the equivalence ratio is from 0.3 to 1.0, the temperature rise is from 1150 K to 2050 K. This indicates that hydrogen could serve as fuel for high temperature rise combustors, if the security of storage can be solved easily. Figure 6: Turbulence kinetic energy contours compared for count-swirling four-point LDI combustors with different equivalence ratios. Figure 9 shows the EI\({}_{\text{NO}}\) profiles of co-swirling and count-swirling four-point LDI combustors with different equivalence ratios. With the equivalence ratio decreasing, the EI\({}_{\text{NO}}\) are reduced sharply in the four-point LDI combustors with the equivalence ratio from 0.6 to 1.0. Corresponding to equivalent ratio of 0.6, the total temperature is approximately 1800 K. Therefore, the tendency of EI\({}_{\text{NO}}\) is in line with the formation mechanism of thermal NO [42,43] which is directly related to temperature when the combustion temperature is more than 1800 K. This verifies the validation of the formation model of NO for numerical simulation. While the equivalence ratio is less than 0.6, the EI\({}_{\text{NO}}\) value is very low and the mass fraction of NO is very small. Figures 8 and 9 show the total temperature and EI\({}_{\text{NO}}\) contours in the co-swirling and count-swirling four-point LDI combustors with the equivalence ratio of 0.5. For co-swirling and count-swirling four-point LDI combustors with different equivalence ratios, the EI\({}_{\text{NO}}\) contours are very similar to the one in the four-point LDI combustors with different equivalence ratios.