Partially Premixed Combustion Non-Adiabatic Chemical Equilibrium CFD Simulation

Partially Premixed Combustion, Non-Adiabatic, Chemical Equilibrium, ANSYS Fluent CFD Training

Welcome to the eighth episode of our comprehensive “Combustion: All Levels” course. In this advanced lesson, we delve into the complexities of partially premixed, non-adiabatic combustion simulation using ANSYS Fluent software. This episode focuses on chemical equilibrium modeling in a unique setup where pure air and a fuel-air mixture interact within the combustion chamber.

Simulation Overview

Our simulation centers on a two-dimensional combustion chamber model, where we’ll investigate the dynamics of partially premixed combustion under non-adiabatic conditions. This episode aims to provide a thorough understanding of the complex interactions between pure air and a pre-mixed fuel-air mixture, mimicking scenarios commonly found in advanced combustion systems.

Model Geometry and Meshing

The foundation of our simulation lies in a carefully crafted model:

• Geometry designed using Design Modeler software for precision
• Meshing performed with ANSYS Meshing software
• Structured mesh type for optimal accuracy
• 4,700 elements ensuring detailed results while maintaining computational efficiency

This meticulous setup ensures that our simulation captures the nuances of the partially premixed combustion process with high fidelity.

Simulation Methodology

Partially Premixed Combustion Model

We employ the Partially Premixed Combustion model to simulate the combustion process effectively:

• Non-adiabatic energy treatment for realistic heat transfer modeling
• Chemical equilibrium approach for accurate species prediction
• Separate inlets for pure air and fuel-air mixture to simulate advanced combustion systems

Probability Density Function (PDF) Table

A key component of our simulation is the pre-generated PDF table:

• Stores data on temperature variations, mixture density, and species mass fractions
• Enhances computational efficiency during main calculations
• Provides a robust framework for chemical equilibrium modeling

Turbulent Flame Speed Model

We utilize the Zimont model for the Turbulent Flame Speed:

• Accurately predicts flame propagation in turbulent flows
• Accounts for the interaction between turbulence and chemical reactions

Simulation Stages

Our simulation process is divided into two key stages:

1. Cold flow simulation: Initial solution for flow patterns without combustion
2. Combustion simulation: Enabling combustion equations and using the patch option for progress variable initialization

Additional Settings

To ensure a comprehensive simulation, we also:

• Enable the Energy equation to track temperature changes accurately
• Utilize the Standard k-epsilon model for turbulence modeling

Results and Analysis

Upon completion of the simulation, we’ll analyze a range of outputs:

• Temperature distribution contours
• Velocity profiles throughout the chamber
• Mass fractions of various species
• Streamlines revealing flow patterns and mixing zones

These results will provide valuable insights into:

• The progression of combustion in a partially premixed environment
• Temperature evolution due to non-adiabatic conditions
• Species formation and consumption patterns
• The role of secondary flows in enhancing mixing and combustion

Learning Outcomes and Applications

By the end of this episode, you’ll have gained:

• Advanced understanding of partially premixed, non-adiabatic combustion simulation techniques
• Insights into chemical equilibrium modeling in CFD
• Skills to interpret CFD results for complex combustion systems
• Knowledge of how to simulate and analyze multi-stage combustion processes

These skills are directly applicable to:

• Designing advanced gas turbine combustors
• Optimizing dual-fuel engine systems
• Improving combustion efficiency in industrial furnaces
• Advancing research in partially premixed combustion phenomena

Join us in this cutting-edge exploration of partially premixed, non-adiabatic combustion simulation using ANSYS Fluent, and elevate your CFD expertise to new heights in advanced combustion modeling!