## 3 Results and Discussion
### Comparison EDM and KSD Model  
Taking the higher diffusivity of hydrogen into account, the high-temperature zone shifts downstream towards the nozzle and the outer sides of the flame. An example of the influence of the selected diffusion model and its influence on the temperature distribution within the flame is given in Figure 2. While this effect is not noticeable in the results of the EDM model, the modified model can detect high-temperature risk points and predict the heat development towards the nozzle. These findings are in good agreement with the results reported in the work of [PERSON] et al. (2016) and [PERSON] et al. (2018). Influence of the selected diffusion model in the temperature and mass is especially emphasized in the flame zone, close to the gas inlet. The solid line demonstrates the results from the calculation with differential diffusion while the dashed lines show the distribution of components and temperature without component-specific diffusion. It is a general tendency that the influence of the selected diffusion model on the temperature and mass fraction distribution is reduced further upstream from the gas inlets. For example, 25 mm downstream of the gas inlet (Figure 3) only slight differences are noticeable in the case of mass fraction distribution of oxygen and water. Since for the KSD model, the hydrogen is consumed by the reaction process closer to the nozzle, the oxygen concentration is 30% higher compared to the EDM model, and therefore the ratio of water is 35% lower. The temperature distribution at this height is similar for both models. The impact of the high diffusivity of hydrogen causes higher differences as the observation plane comes closer to the gas inlet. At a 5 mm height (Figure 4), the temperature is 239 K higher and 30% wider. This is a result due to the fast mixing of hydrogen with air and the therefore earlier starting reaction process. While for the EDM model there is still 5% of H\({}_{2}\) left over, it is completely consumed for the modified calculations which are also partially responsible for the flatten curvature for the O\({}_{2}\) and H\({}_{2}\)O concentration. The closer the results are taken from the nozzles, the higher is also the H\({}_{2}\) concentration for both models. The distribution of hydrogen 0.5 mm upstream from the inlet is about 56% lower for the modified model than for the EDM model (Figure 5). Figure 3: Temperatur and mass fraction at a height of 25 mm; solid line: with differential diffusion, dashed line without differential diffusion. Figure 2: Temperature distribution for the model with (**left**) and without (**right**) considering component specific diffusion. It is assumed that the combination of differentiated transport properties and the changed number of moles in the gas mixture affect the nitrogen mass fractions. The reduced decrease in the nitrogen concentration along the centreline is caused by the changed hydrogen distribution. While in the EDM model, hydrogen flows into the combustion chamber as a jet and displaces the existing air with a high percentage of nitrogen, H\({}_{2}\) diffuses away to the outside more readily in the modified model. This results in a higher N\({}_{2}\) concentration behind the nozzles. As the number of moles decreases during hydrogen combustion, the N\({}_{2}\) concentration increases in this region. Regarding the water concentration, the result of the calculation for the KSD model differs from those obtained in previous studies. Due to the chosen nozzle diameter, the inner two maxima for both models are much closer to each other than in previous studies (Figure 5). Moreover, it is noticeable that there is a dip in the water concentration above  
Figure 4: Temperature and mass fraction at a height of 5 mm; solid line: with differential diffusion, dashed line without differential diffusion. Figure 5: Temperature and mass fraction at a height of 0.5 mm; solid line: with differential diffusion, dashed line without differential diffusion. the air inlet.