After a substantial number of computations, the study of fuel and air mixing in a ramjet shows that an adapted configuration can be eventually determined. Indeed, to reach satisfactory conditions, the flow has to be turbulent, which implies that the fuel inlet velocity must be sufficiently high to develop turbulent structures. Nevertheless, as the flow rate increases with the fuel inlet velocity too, it can happen that some areas still show more fuel than air. Thus, despite the global mixing and the high fuel inlet velocity, it is possible to find fuel without air in the combustion area. Therefore, the fuel inlet velocity has to be greater than a "laminar flow" value and while staying lower than a "fuel without air flow" value.
When the air inlet velocity is 61 m/s, the fuel inlet velocity must be greater than 100 m/s and lower than 300 m/s.
Other runs have permitted to reduce the range of possible values of the fuel inlet velocity from 150 m/s to 250 m/s.
Within only a few runs, an interesting fuel inlet velocity has been found out : namely, if the fuel velocity is 195 m/s, the flow is turbulent and no fuel remains without air in the combustion area.
This optimum velocity is not extremely precise as both the working time and the number of iterations were not sufficient : hence, the quality of the mixing could possibly be enhanced with longer simulation runs.
To conclude, this study was really a good opportunity to discover AVBP, which is a famous and powerful CFD code.