CFD-Based Investigation of Internal Flow Structure and Geometric Optimization of a Supersonic Ejector

Supersonic ejectors are widely used in refrigeration systems due to their potential to improve system performance. However, their performance is highly sensitive to geometric parameters, requiring both a comprehensive understanding of internal flow behavior and systematic investigation. In this study, a CFD model validated against experimental data reported in the literature is used to investigate and optimize ejector performance under fixed operating conditions with particular attention to internal flow characteristics. The effects of key geometric parameters are analyzed using single-factor analysis, followed by a multi-factor analysis using an orthogonal test method. According to the CFD results, the optimized configuration increases the entrainment ratio from 0.442 to 0.526, representing an 18.8% improvement. The critical back pressure decreases from 217.2 to 206.2 kPa, corresponding to a 5.04% reduction, indicating a trade-off between entrainment performance and the stable operating range. This study highlights the importance of linking performance to flow structure, providing a more physically grounded basis for ejector analysis and optimization.