80_Premixed Combustion

Today, we will follow an example provided by Ansys Fluent to learn about CFD analysis.

 

This case is a partially premixed combustion scenario, featuring inflows that reflect both mixed and non-mixed conditions. The fuel, a methane and air mixture, has an equivalence ratio of 0.8 and is injected at a temperature of 300K with an axian velocity of 50m/s and a swirl velocity of 30m/s. Air is injected axially at a temperature of 650K and a speed of 10m/s, with no swirl. The physical combustion chanber is assumed to be cylindrical in this case, which can be represented by a shape rotated around the axis of symmetry.

 

ref : courses.ansys.com.

 

In this problem, the Probability Density Function (PDF) method is utilized to track the mixture fraction and model the chemical species whthin the system. Additionally, it explores and analyzes appropriate inputs and solvers to reduce turbulence quantities.

 

In the Setup under the Models' Species option, change the fuel Stream Rich Flammability Limit to 1 in the Chemistry tab. This allows for equilibrium calculations at all mixture fractions. In the Boundary tab, you can set the equivalence ratio and the injection rates, temperatures of methane and air. The equivalence ratio is defined as the ratio of fuel to oxidizer. Through this setting, air is injected outside the fuel stream at a temperature of 650K.

 

 

The results can be observed as follows.

 

temperature

mass fraction of H2

turbulent flame speed

velocity

 

Through this example, it became clear how to visually observe results via various contours, providing a detailed understanding of the mothod.