Numerical simulation of subsonic jet ejector

Abstract

An ejector is a pumping device that uses a high-speed primary fluid jet to entrain a secondary stream. In this work, using CFD we simulate subsonic air – air ejector numerically. Governing equations including continuity, momentum and energy equations are solved numerically based on finite volume method. Numerical simulation is carried out in 3 dimensions and flow is assumed to be conservative, viscous and turbulent. To simulate turbulences, Reynolds averaged Navier–Stokes, K-ε Standard, K-ε RNG, K-ε Realizable, K-ω Standard and K-ω SST are applied. Ejecting coefficient for various pressure ratios was an effective parameter which was used to validate numerical results. Error was at its minimum for K-ε RNG turbulence model. Therefore, it was used to simulate turbulences. After validating results, we analyzed the effect of geometrical parameter of diffuser outlet diameter and divergence angle on performance of subsonic air – air ejector. Results demonstrate that in addition to divergence angle, diffuser outlet diameter has a significant influence on performance and efficiency of such devices.

Keywords

• ejector
• diffuser divergence angle
• ejector efficiency
• numerical simulation