Influence of Geometrical Parameters on Supersonic Steam-Ejector Performance

Abstract

Geometrical parameters such as the nozzle exit position (NXP) and the diameter ratio (DR) considerably influence the performance of steam ejectors. An axisymmetric two-dimensional model for a supersonic steam ejector is developed to investigate the steam-ejector performance with the aim of simultaneously optimizing the NXP (-10 < NXP < 10) and DR (6 < DR < 10), and the simulation results are in good agreement (relative error was merely 7%) with the experimental results. At the optimum value of the NXP, the supersonic steam ejector acquires the optimal entrainment ratio (ER) under the given conditions. Deviation from the optimal NXP value may result in a 12.4% decrease in ER. With optimized NXP, the optimization of DR is more significant; however, a deviation from the optimal DR weakens the ER and the supersonic steam ejector eventually breaks down. Therefore, the NXP should be approximately close to its optimum value, and the DR must be designed at its optimum value to ensure effective operation of the supersonic steam ejector.