Injector: 2-Phase Flow, VOF Model

Multi-Phase Flow in an Injector (Two-Phase VOF Model) — ANSYS Fluent CFD Simulation

Description

Welcome to the Injector CFD Simulation module. This project introduces multiphase flow analysis within a fuel injector — a critical component across combustion systems in automotive, aerospace, and energy applications — using the Volume of Fluid (VOF) multiphase model in ANSYS Fluent. Inside an injector, liquid fuel and the surrounding gas meet and interact within confined, narrow internal passages, and capturing that dynamic liquid–gas interface is the core of the problem. Injector simulations of this kind support automotive fuel systems, aerospace propulsion, and industrial combustion. Within the Multiphase Flow: Beginner CFD Training Package, this project applies the VOF model to a real device, moving from free-surface flows to two-phase flow inside a confined injector geometry.

Methodology

The project uses a pre-configured injector model, examining the key geometric features of a realistic injector design along with the mesh characteristics needed to resolve the liquid–gas interface within its narrow internal passages. Realistic operating conditions are defined, including appropriate pressure, velocity, and fluid-property settings at the fuel inlet, along with proper representation of the surrounding gas phase and the wall boundaries. The VOF model is central to the setup: the VOF scheme is selected and configured for stable, accurate interface capture within the injector's complex internal geometry, and surface tension and turbulence effects are incorporated, since these govern the fluid behavior during injection. The case is solved as a steady-state simulation.

Analysis

Post-processing interprets the multiphase flow behavior through contours and animations showing the spatial distribution of liquid fuel and gas, alongside quantitative assessment of velocity profiles, pressure distributions, and spray characteristics at the nozzle exit. From these results you can examine how the injection pressure influences the flow behavior and phase distribution, how the nozzle geometry could be optimized to improve atomization and spray quality, and how to evaluate injector efficiency, flow uniformity, and potential cavitation risk. These insights connect directly to optimizing fuel-injection systems for better engine performance and cleaner, more efficient combustion. By the end of this project, you'll be able to set up an injector simulation with the VOF two-phase model, configure interface tracking with surface tension and turbulence in a confined geometry, and interpret the volume-fraction, velocity, and pressure results that characterize liquid–gas interaction in a high-pressure injection system.