Analysis of steam ejector performance with corrugated nozzle

Performance of a steam ejector mounted with corrugation shaped primary nozzle was analyzed, after a three-dimensional simulation model was built and verified with experimental results of the ejector with an ordinary nozzle. The effects of the number of corrugations (Cn), amplitude (h/D), ratio of the length covered by corrugation (l/L) and the angle twisted of the corrugation (θ) on entrainment ratio (ER) and critical back pressure (CBP) were investigated. Analysis of the vortex (stream-wise and span-wise) formed in the mixing chamber showed that the vortex with larger strength and a longer life span results in higher ER. As the secondary flow rate increases and the turbulence gets intense, the loss of the mechanical energy increases, leading to the decrease of CBP. While the span-wise vortex contacts too early with the wall of the mixing chamber, the vortex will decay rapidly and both the ER and CBP will decrease. In the range covered by this paper, compared with the nozzle without corrugation, ER can increase by up to 13.9% and the corresponding CBP decreases by 5.1%. © 2014 Chin. Soc. for Elec. Eng.