CFD Studies on Ejectors Configured with Twisted Circular Profile Lobed Nozzle

An ejector is a thermo compressor with no moving parts and is used to compress the low-pressure stream to a higher intermediate pressure using a high-pressure stream. This study investigates a 3D numerical analysis of a supersonic ejector using R134a, aiming to enhance momentum exchange between the primary and secondary streams. The predicted entrainment ratio is validated with the data available in the literature. The diffuser part of the convergent-divergent primary nozzle is modified to a twisted lobed structure extending through the throat of the primary nozzle. To predict shock wave structure and the ejector performance, the k-ω SST turbulence model with NIST REFPROP v9.1 database equation has been used. The numerical results have revealed that, the pressure difference has been observed between the lobs tip and crest of the lobs, thus making the low-pressure stream sucked into the mainstream and resulting in a high momentum exchange and energy transfer between the two primary and secondary streams. About 7% enhancement in entrainment ratio is seen for a 3-lobed with a 45° twist nozzle ejector without normal shock.