## 1 Introduction
[10] employed a CFD method to investigate the influence of mixing chamber geometries on the performance of the steam ejector used for the multi-effect distillation system. [PERSON] et al. [11] studied the primary flow jet core patterns in the steam ejector using numerical simulations and focused on the relationship between the primary pseudo-shock pattern and ejector performance. The section shape and position of the nozzle exit were all-important geometric parameters that played a critical role in improving the ejector performance, which was verified in [12; 13; 14; 15]. [PERSON] et al. [16] numerically simulated a novel ejector with a bypass installed in the low-pressure district to enhance the ejector entrainment ratio. [PERSON] et al. [17] designed an adaptive nozzle exit position (ANXP) ejector that automatically adjusts the nozzle position as the variation of operating conditions and regulated the performance of the MED-TVC desalination system. For maximum efficiency of the MED-TVC desalination system and to reduce energy consumption, [PERSON] et al. [18] changed the ejector suction location from the last to the middle effect using the CFD method. Many scholars employed the \"single-fluid\" approach, also called the wet steam model [19; 20; 21], to numerically simulate steam ejector spontaneous condensation phenomenon; the \"two-fluid\" approach has also been applied by developing commercial codes [22] or in-house solvers [23; 24]. In the studies mentioned above on the experiment or numerical simulation aspects, all scholars assumed that the working fluid is pure steam and ignored the presence of air. However, in producing and transmitting steam, air is mixed into the steam more or less because the experiment equipment cannot guarantee absolute sealing effectiveness for a long time. [PERSON] et al. [25] experimentally researched a two-phase ejector for a desalination system with water as the primary fluid and air as the secondary fluid. [PERSON] et al. [26] experimentally and numerically investigated the hydrodynamic characteristics of a two-phase ejector with water as the primary fluid and a mixture of air and water as the entrained flow. [PERSON] et al. [27] used a mixture of water and steam by injecting water nano-droplets into the primary fluid inlet of a steam ejector in order to numerically investigate the effects of water droplets on the two-phase parameters, shock wave intensity and entrainment ratio. [PERSON] et al. [28] also injected water into the secondary flow (air) to experimentally and numerically study the performance of a two phase flow air ejector. However, there is a lack of research on the sensitivity of the performance of a steam ejector when different mass fractions of air are leaked into the primary and secondary fluids. To fill this scientific gap, we numerically used the mixture model to make steam and air with different mass fractions for the working fluid. The present study was to determine the effect of air leaking into the working fluid on the steam ejector performance, determine the cause of the change in steam ejector performance, and provided a valuable reference for air leakage inspection for experimental steam ejector refrigeration systems (RES).