Time Step Size effect on Particle Injection in Combustion Chamber, ANSYS Fluent CFD Simulation Tutorial

Description

The purpose of this simulation is to show the entry of solid particles as fuel inside the combustion chamber. In this simulation, we intend to inject the particles from the nozzle exit into the combustion chamber with high accuracy.

For this reason, the effect of time steps on the movement of particles in two different time steps is investigated. Two simulations have been performed with the final time step of 0.0005 and 0.001.

The boundary conditions are considered as inlet velocity and outlet air pressure. In this CFD simulation, combustion is not modeled, and only particle injection is considered.

The geometry of the present model is three-dimensional and has been designed using Design Modeler software. We do the meshing of the present model by ANSYS Meshing software. The mesh type is Polyhedra, and the element number is 859,934.

Methodology: Time Step Effect on Particle Injection

The Discrete Phase Model (DPM) is used to simulate the Injection of solid particles (Inert) in the combustion chamber-Surface injection Type.

Conclusion

Considering two simulations with different time steps,  this problem provides more realistic and tangible results of particle injection at time steps between 0.0001 and 0.0005. While at the time step size between 0.0005 and 0.001, the particle collision with the wall is shown schematically incorrect.

From the results of this simulation, we realized that the effect of the time step size parameter on the behavior of particles is very effective. In such problems, it is necessary that the injection of particles is independent of the time step.