## 4 Results and Discussion
### The Effect of the Air Leaked into the Secondary Fluid on the Ejector Performance
#### 4.2.3 Distribution of the Species Component with Air Leaking into the Secondary Fluid  
Figure 14 illustrates the species component distribution inside the eject with air leaking into the secondary fluid. The red region with the large air mass fraction is the secondary fluid in the mixing chamber inlet. The blue region with a tiny air mass fraction is the shock train of the primary fluid and was distributed along the eject axis and disappeared in the diffuser. The green region in the mixing chamber and throat is the mixing zone of the primary and secondary fluids, and it was also considered the mixing layer of the two fluids. In addition, the air mass fraction in the mixing layer gradually  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \(Y_{2}\) & **Steam** & **Velocity** & **Density** & **Sound** & **Er** \\  & & **U (m/s)** & **P (kg/m\({}^{3}\))** & **_a (m/s)_ & \\ \hline \multirow{3}{*}{0.0} & Pri & 1048.5 & 0.0318 & 279.20 & 0.398 \\  & Sec & 185.37 & 0.0085 & 405.49 & \\ \cline{1-1}  & Pri & 1048.5 & 0.0318 & 279.20 & 0.399 \\ \cline{1-1}  & Sec & 181.52 & 0.0088 & 398.45 & \\ \cline{1-1}  & Pri & 1048.5 & 0.0318 & 279.20 & 0.417 \\ \cline{1-1}  & Sec & 173.86 & 0.0096 & 384.07 & \\ \cline{1-1}  & Pri & 1048.5 & 0.0318 & 279.20 & 0.435 \\ \cline{1-1}  & Sec & 165.30 & 0.0105 & 369.32 & \\ \hline \hline \end{tabular}
\end{table}
Table 6: Physical parameters of different \(Y_{2}\) values.  
Figure 12: Isolines of the secondary flow mass flux with different \(Y_{2}\) values.  
decreased along the ejector axis. Meanwhile, a fully mixing zone with the same air mass fraction was formed near the outlet of the ejector.  
As discussed in Section 4.1.2, the larger the Mach number of the primary fluid jet core in the diffuser is, the further downstream the shock position formed by this jet core. However, this conclusion is contradicted by the result of Figure 13; in the diffuser, we clearly observed that the shock position of the primary fluid jet core at \(Y_{2}=0\) was further upstream in the diffuser than at other \(Y_{2}\) values (see Figure 13a), but its Mach number was smaller than others, as illustrated in Figure 13b. This phenomenon could be attributed to two points: The air in the secondary fluid would downgrade the energy required to entrain the secondary fluid, while the kinetic energy of the primary fluid flowing from the nozzle remained the same; and the air in the secondary fluid enhanced the mixing effect (this conclusion is confirmed in Section 4.3) As shown in Figure 14, the most intense mixing effect usually occurred in the full mixing zone in the diffuser; the more intense the mixing effect, the more kinetic energy of the primary fluid to transform into the mixing energy. Based on the analysis of the above two points, the Mach number of the primary fluid jet core with air leaking into the secondary fluid was smaller than that without air in the diffuser. In addition, the shock position farther downstream could also be attributed to the intense mixing effect in the diffuser. The detailed structure and effect of the mixing layer and the relationship between the mixing layer effect and the entrainment ratio is discussed in Section 4.3.  
Figure 14: Air mass fraction distribution with different \(Y_{2}\) values.  
Figure 13: Primary fluid flow state with different \(Y_{2}\) values: (**a**) shock pattern and (**b**) Mach number.