# Impact of Mesh Resolution and Temperature Effects in Jet Ejector CFD Calculations
## 1 Introduction
The further transgressing of pressure values from the previsioned ones eventually causes malfunctions. This is characterized by a reversed secondary flow causing the ejector to be inoperative [12]. Therefore, design optimization seeks to expand the range of effective off-design operations without significant performance losses [13]. The behavior of jet ejectors under varying operational conditions has been studied, with particular emphasis on the effects of pressure changes because their performance is strongly dependent on the ratio of secondary to primary pressures. This ratio dominates the ability of the ejector to entrain and compress the secondary flow. Studies have shown that the maximum operational pressure ratio is influenced by the design and operating conditions of the ejector. For instance, [PERSON] et al. demonstrated that the primary nozzle reaches sonic conditions when the motive-to-secondary pressure ratio exceeds a certain number, leading to choked flow [10]. Beyond this, increasing the pressure ratio causes a decline in the entrainment performance. Similarly, [PERSON] and [PERSON] identified that the operational range of pressure ratios is limited by the onset of flow separation or reverse flow phenomena at the diffuser, which occurs under high back-pressure conditions [14]. These findings create working ranges for ejectors, dictated by pressure ratios, and sur passing these results in malfunctions or severely degraded performances. Those studies focus on the influence of pressure changes on the ejectors' behavior. Although they are undoubtedly very impactful criteria, these authors highlight a knowledge gap lying in understanding the effect of changes in inlet temperatures, as limited attention has been given to this query. [PERSON] and [PERSON] also investigated the behavior of ejectors, specifically focusing on the relationship between the primary shock train (PST) length and the ejector entrainment ratio [15]. They observed a PST length increase results in a decrease in the entrainment ratio at a given motive pressure in convergent-divergent nozzle ejectors. Additionally, they noted that reducing the PST length enhances the suction mass flow rate in the sub-critical mode. In related research, [PERSON] et al. simulated a supersonic steam ejector, neglecting the condensing effect. Their findings indicated that a normal shock wave in the diffuser maintains the ejector in the choked flow mode by preventing disturbances caused by the Pout (outlet pressure) [16]. Similarly, [PERSON] et al. employed an ideal gas model and concluded that the steam ejector performance approaches optimal levels when the shock diamonds are weak. Subsequently, a sudden drop in Mach number signifies the occurrence of an aerodynamic oblique shock wave, while a sudden rise indicates an expansion wave. These phenomena form diamond shock waves placed around the nozzle exit, which collectively constitute the PST region in the jet core of the mixing chamber. When the mixed steam pressure needs to be reduced to accommodate a low discharge pressure, aerodynamic shock waves reappear in the diffuser to dissipate excess energy, marking the second shockwave region under specific conditions (in this case--dictated by pressure) [17]. Therefore, the abrupt drop in Mach number identifies the shock waves positions. Despite the known insights, still little information is available on how variations in other governing parameters influence the ejector performance under changed operational regimes. Hence, the novelty of this work is an attempt to research this and generalize the findings to establish a comprehensive guide for jet ejector operation. By considering broader parameter variations, creating consecutive performance maps, and analyzing the Mach number distribution, this study aims to expand the applicability of jet ejectors and enhance their adaptability across diverse operating conditions in refrigeration cycles.