The Effect of Reynolds Number on Jet in Asymmetric Co-Flows: A CFD Study

Abstract EN

In rotary kilns in grate-kiln systems for iron ore pelletizing, a long and stable jet flame is needed to ensure a high quality of the pellets.

The primary jet issuing from the nozzle interacts with two asymmetric co-flows creating a very complex flow.

In order to better understand and eventually model this flow with quality and trust, simplified cases need to be studied.

In this work, a simplified and virtual model is built based on a down-scaled kiln model established in a previous experimental work.

The aim is to numerically study the jet development as a function of position and Reynolds number (Re).

The numerical simulations are carried out with the standard k-ε model, and quite accurate velocity profiles are obtained while the centerline decays and spreading of the passive scalars are over predicted.

The model is capable of predicting a Re dependency of the jet development.

With increasing Re, the jet is longer while it generally decays and spreads faster resulting from the stronger shear between the jet and co-flows and the stronger entrainment from the recirculation zone.

This recirculation found in the simulations restrain the momentum spreading in the spanwise direction, leading to a slower velocity spreading with higher Re.

For further validation and understanding, more measurements in the shear layer and simulations with more advanced turbulence models are necessary.