Optimization of Steam Ejector Nozzle Structure Based on Orthogonal Test

Computational fluid dynamics (CFD) techniques combined with orthogonal test methods were used to optimize the structural parameters of steam ejector nozzles to improve efficiency. With the objective of simultaneously optimizing the shape curve of the nozzle shrinkage section, the throat length, and the angle of the diffusion section, and taking the entrainment rate (ER) and critical back pressure (CBP) as the performance indexes, the L₉(3³) orthogonal table was established to develop nine sets of test protocols with 77 cases. A wet steam model was used to calculate the phase change phenomena during steam flow. The importance of three parameters was determined through range analysis, and the overall flow field and nozzle flow field were analyzed. The results show that the main factor affecting the working steam flow rate, entrainment rate, and critical back pressure of the steam ejector is the shape curve of the nozzle contraction section; quadratic curves, shorter throat lengths, and larger diffusion section angles contribute to lower nozzle resistance and higher working steam flow rates; the wet steam model takes into account the condensation phenomenon of the ejector and provides a more realistic calculation of the flow inside the ejector.