## 5 Results and Discussion
### Wettness Influences of Inlets on Entrainment Ratio  
Condensation occurs in the nozzle of the steam ejector and results in the formation of water droplets. These water droplets pass through the steam ejector in the primary flow and have significant influence on the mixing process and the flow behavior. The wet steam is a mixture of saturated vapor and fine liquid droplets, and the wetness is defined by the liquid mass fraction. In this article, four working conditions with different wetness settings on the primary and secondary flows were chosen to investigate the effects of wetness on the condensation effect. The case details are listed in Table 3.  
_Case 1_ is a virtue case which tests a totally dry fluid stream, which means both the liquid mass fraction of primary and secondary flow are set as zero. _Case 4_ is more like the actual scenario since in reality there is humidity and the steam should be somewhat wet. The liquid mass fraction was set to 0.1 on both inlet flows, which corresponds to the fact that most nozzle and turbine flows will have a wetness factor less than 0.1. In addition, large values of the wetness fraction lead to instability in the solution due to the large source terms in the transport equations. The axial static temperature distribution for the 4 case studies are illustrated in Figure 10. _Case 1_ and 2 shows a slightly different trend to _Case 3_ and 4 during the nozzle section. It is proven that the wetness of primary flow has a more significant effect on the condensation in comparison to that of secondary flow. The gap in temperature distribution along the axis position between _Case 1_ & 2 and _Case 3_ & 4_ is due to the heat realized from the condensation effect. From Figure 10, it is also concluded that: (i) For _Case 1_, since both the primary and secondary flow are totally dry, the condensation effect is the most significant and can be reflected from the figure as it has the highest temperature overall. (ii) On the contrary, _Case 4_ has the least condensation effect since the incoming fluid has the greatest moisture content before it approaches the mixing chamber. (iii) Compared with _Case 4_, the temperature of _Case 2_ in the nozzle part is higher since the condensation happened in the nozzle and some latent heat was released due to the condensing effect, which leads to a delay of the temperature drop. (iv) _Case 3_ shows the same trend of _Case 4_ during the nozzle part because the wetness of primary flow is the same. For the mixing chamber, with the different wetness of secondary flow, the condensation of secondary fluid for _Case 3_ occurred and the process released heat to the mixed flow, leading to an increased temperature. (v) _Case 2_ and \(3\) illustrates that the wetness of the primary flow has a more significant effect on the condensation in the whole working process of the steam ejector compared to the secondary flow. From Figure 11, it is concluded that during the mixing process, the nucleation rate is high, and droplets were generated, which means that condensation is still happening in the mixing chamber. Compared to _Case 4_, _Case 3_ shows a wider area of droplets nucleation, which leads to a higher entrainment ratio. Theoretically, reducing the wetness of secondary flow has a positive impact on improving the entrainment ratio and the performance of the steam ejector. With less wetness of the secondary flow, the nucleation can last from mixing chamber to throat, which increases the range of condensation effect and improves the entrainment ratio of the steam ejector. The pumping efficiency of the steam ejector was calculated based on the Equation (1) for all four cases, which was summarized in Figure 12. Compared to the ideal gas model, the entrainment ratio of _Case 1_ and \(3\) was improved, due to the application of the wet steam. The condensation effect was taken into consideration during the pumping progress by using the wet steam model, and the primary flow entrained more secondary flow, which improves the pumping efficiency.