How do you couple CFD with experimental measurements for combustion analysis?

1 Experimental techniques

To measure the properties of combustion, such as temperature, pressure, velocity, and species concentrations, various experimental techniques are available. Some of the most common ones are thermocouples, pressure transducers, laser-based methods, and optical methods. Thermocouples and pressure transducers are intrusive methods that require physical contact with the flame, while laser-based and optical methods are non-intrusive and rely on the interaction of light with the combustion species. Each technique has its advantages and limitations, depending on the accuracy, resolution, cost, and safety requirements.

2 CFD models

CFD models are mathematical representations of the physical processes that occur in combustion. They solve the governing equations of mass, momentum, energy, and species conservation, along with the chemical kinetics and turbulence models. CFD models can be classified into different levels of complexity, such as laminar, turbulent, premixed, non-premixed, and partially premixed. The choice of the model depends on the type of combustion system, the available computational resources, and the level of detail required.

3 Coupling methods

To couple CFD with experimental measurements, there are two main methods: direct and indirect. Direct coupling means that the experimental data are used as inputs or boundary conditions for the CFD model, such as the inlet velocity, temperature, and composition. Indirect coupling means that the experimental data are used to validate or calibrate the CFD model, such as comparing the predicted and measured temperature or species profiles. Both methods require a careful selection of the experimental and numerical parameters, such as the spatial and temporal resolution, the measurement uncertainty, and the model sensitivity.

4 Visualization tools

To visualize the results of the coupled CFD and experimental data, there are various tools and software available. Some of the most popular ones are Paraview, Tecplot, and ANSYS Fluent. These tools allow the user to create plots, graphs, contours, and animations of the flow, temperature, pressure, and species fields. They also enable the user to compare the CFD and experimental data, such as overlaying the predicted and measured temperature or species profiles, or calculating the error or deviation between them. Visualization tools help the user to gain insight into the combustion behavior and identify the strengths and weaknesses of the CFD model.