Non-premixed Combustion Steady Diffusion Flamelet CFD Simulation

Non-premixed Combustion, Steady Diffusion Flamelet, ANSYS Fluent CFD Training

Welcome to the fourth episode of our comprehensive “Combustion: All Levels” course. In this advanced lesson, we delve into the intricacies of non-premixed combustion simulation using ANSYS Fluent software, with a focus on the Steady Diffusion Flamelet model. This episode provides valuable insights into complex combustion processes commonly found in industrial applications.

Simulation Overview

Our simulation centers on a two-dimensional combustion chamber model, where we’ll investigate non-premixed combustion dynamics using a sophisticated CFD approach. This episode aims to provide in-depth understanding of the interaction between fuel and air when introduced separately into the combustion chamber, mimicking real-world scenarios.

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
• 63,280 elements ensuring detailed results and high-resolution analysis

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

Simulation Methodology

Non-Premixed Combustion Model

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

• Non-adiabatic energy treatment for realistic heat transfer modeling
• Steady Diffusion Flamelet approach for accurate flame structure prediction
• Separate fuel and air inlets to simulate real-world combustion chambers

This approach allows for a comprehensive analysis of the complex mixing and reaction processes occurring during non-premixed combustion.

Chemkin Mechanism and Flamelet Generation

A key component of our simulation is the use of a Chemkin mechanism:

• Imported into Fluent to create the flamelet
• Models the turbulent flame brush as an ensemble of discrete, steady laminar flames
• Provides a detailed representation of chemical kinetics

Probability Density Function (PDF) Table

To enhance computational efficiency, we generate a PDF table:

• Stores data on temperature variations, mixture density, and species mass fractions
• Pre-computed before the main simulation for faster calculations
• Allows for accurate representation of turbulence-chemistry interactions

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 structure and behavior of non-premixed flames
• Temperature evolution in different regions of the combustion chamber
• Species formation and consumption patterns
• The role of secondary flows in enhancing mixing and combustion efficiency

Learning Outcomes and Applications

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

• Advanced understanding of non-premixed combustion simulation techniques
• Insights into the Steady Diffusion Flamelet model and its applications
• Skills to interpret CFD results for complex combustion systems
• Knowledge of how to use Chemkin mechanisms in Fluent for detailed chemistry modeling

These skills are directly applicable to:

• Designing more efficient industrial burners and furnaces
• Optimizing fuel injection systems in gas turbines and diesel engines
• Improving combustion chamber designs for reduced emissions
• Advancing research in non-premixed combustion phenomena

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