Prediction of condensation shock in supersonic nozzle: Comparison between high-pressure and low-pressure conditions at different of superheating degree

The expansive superheated region, characterized by a broad pressure spectrum, presents a significant challenge in industrial equipment design. To address this, we investigate non-equilibrium condensation (NQC) phenomena in a supersonic nozzle across a wide range of pressures and degrees of superheat. Our results reveal marked disparities in flow behavior between high- and low-pressure conditions within this region. Entropy generation reaches a maximum at a particular superheat level, and frictional losses constitute the primary contributor to entropy generation within the superheated region. The position and intensity of the condensation shock are sensitive to fluctuations in stagnation pressure and degree of superheat. Importantly, in saturated and high-pressure regimes, the flow remains free of condensation shocks. Under low-pressure conditions, mass flow rate exhibits a negative correlation with increasing superheat. In contrast, at high pressures, the relationship is non-monotonic, characterized by an initial rise followed by a decline as superheat levels elevate. The low-pressure flow is characterized by elevated supersaturation ratios and droplet number densities relative to the high-pressure flow. Imposing a 50-degree superheat results in a significant reduction of outlet liquid mass fraction (LMF), with approximately 95% and 63% decreases observed for low- and high-pressure flows, respectively.