Steam Ejector

Steam Ejector — ANSYS Fluent CFD Simulation

Description

This project presents a CFD simulation of a steam ejector — a mechanical device with no moving parts that uses a primary (motive) steam jet to suck in and mix with a secondary fluid. Ejectors perform two essential jobs: creating vacuum for suction and mixing two fluid streams, and they do it by continuously converting between kinetic and pressure energy as the flow passes through a convergent-divergent nozzle. In this project, you'll model water vapor as the motive fluid driving the suction of a secondary fluid, watching the flow accelerate beyond the speed of sound and observing how the vacuum-driven suction physically arises. Within the Compressible Flow: Beginner CFD Training Package, this project applies convergent-divergent nozzle physics to a real industrial device, showing how supersonic internal flow generates suction and mixing.

Methodology

The 2D convergent-divergent (de Laval) nozzle ejector geometry is designed in Design Modeler and meshed in ANSYS Meshing with an efficient structured grid of roughly 52,000 elements suited to internal compressible flow. Because supersonic flow is fundamentally compressible — with density varying strongly with pressure — the density-based solver is used, the correct choice for this class of problem, and the Mach number governs the behavior inside the device. The setup handles the pressure difference between the primary and secondary inlets that drives the suction phenomenon, so the motive steam jet entrains and mixes with the secondary fluid as it accelerates through the nozzle.

Analysis

Post-processing focuses on pressure, velocity, and Mach number contours, tracing where the flow goes subsonic, sonic, and supersonic through the device. From these you can follow how the motive and secondary streams mix and compress downstream of the nozzle throat, and how the vacuum-driven suction arises from the energy conversion in the convergent-divergent passage. Ejectors appear throughout refrigeration, vacuum systems, desalination, chemical processing, and power plants, and the skills built here carry directly into nozzles, diffusers, supersonic airfoils, and any flow where Mach number matters. By the end of this project, you'll be able to set up an internal compressible-flow simulation with the density-based solver, handle the inlet pressure difference that drives ejector suction, and interpret the pressure, velocity, and Mach fields that trace the subsonic-to-supersonic behavior inside the device.