Reacting Flows and Combustion

Understanding and predicting the effects of reacting flows and combustion chemistry are critical to developing competitive products in the transportation, energy generation and materials processing industries, among many others. Knowledge of the underlying combustion chemistry and physics enables designers of gas turbines, boilers and internal combustion engines to increase energy efficiency and fuel flexibility, while reducing emissions. Similarly, reacting flows are key to designing high-throughput materials and chemical processes with high yields and quality, along with minimum byproducts and waste. A thorough grasp of the underlying physics and chemistry is also critical to making improvements in lithium-ion batteries, fuel cells and many other products.

Optimizing the design of these reacting flows and combustion analysis products to achieve a competitive advantage is difficult because they often consist of systems with complex geometries, boundary conditions and physics, including large networks of chemically reacting species, turbulence and radiation. Relying on physical testing alone for performance validation is not a viable option given that today’s shortened design cycles frequently do not allow multiple design and test iterations. Furthermore, the diagnostic information provided by physical testing is often limited by the inability to position sensors in areas that are key to understanding the process.

New: Validated Method of Moments (MoM) Soot Model

The Method of Moments (MoM) soot model provides reliable trend prediction for soot formation in gas turbine combustion simulations. It has been validated on a number of canonical test cases and shows good agreement with experimental data. Selecting an appropriate precursor is a critical part of the soot model; our validation studies provide precursor recommendations. The robustness and accuracy of the model has also been demonstrated on an industrial gas turbine combustor. When combined with Ansys Fluent's FGM combustion model, the MoM soot model provides a state-of-the-art framework for simulating gas turbine combustion and emissions.

Fluent's MoM soot model

Soot peak volume fraction prediction for a set of canonical flames using Ansys Fluent's MoM soot model

As you gain understanding, you can move to more complex 3D models with Ansys computational fluid dynamics (CFD). Accurate reaction mechanisms are provided by the Ansys Model Fuel Library, a database of accurate, detailed chemical mechanisms for over 65 fuel components, representing every class of reaction important for combustion analysis. Ansys simulation tools reduce chemistry analysis time by orders of magnitude, virtually eliminating the bottleneck that chemistry integration produces during the simulation process. Faster time to solution makes it possible to spend more effort exploring design alternatives, conducting experiments, understanding where and why problems occur, and explaining observations without sacrificing accuracy.

Read the Reacting Flows and Combustion application brief

Most Reacting Flows are Turbulent

ANSYS Fluent CFD simulation of a piloted turbulent jet flame (Sandia Flame D benchmark) showing an instantaneous stoichiometric mixture fraction iso-surface combined with plots of temperature and OH mass fraction.

The flows encountered in most of the practical reacting systems are turbulent. In fact, energetic combustion and reaction flows create turbulence through a variety of mechanisms including flow acceleration and modified kinematic viscosity. The turbulence then can alter the flame structure through enhanced mixing and chemical reactions (through temperature fluctuations). And on it goes in a causal loop. Understanding these complex interactions is critical to obtaining accurate results. Turbulence is truly a CFD application you have to get right.

Learn more about Turbulence Modeling for CFD Simulation.