Comparison of flow and dispersion properties of free and wall turbulent jets for source dynamics characterisation

Abstract

The objective of this paper is to provide an investigation, using large eddy simulations, into the dispersion of aircraft jets in co-flowing take-off conditions. Before carrying out such study, simple turbulent plane free and wall jet simulations are carried out to validate the computational models and to assess the impact of the presence of the solid boundary on the flow and dispersion properties.The current study represents a step towards a better understanding of the source dynamics behind an airplane jet engine during the take-off and landing phases. The information provided from these simulations can be used for future improvements of existing dispersion models. Software availabilitySoftware name: FLUENT 6.

Large eddy simulation of plume dispersion behind an aircraft in the take-off phase

“…Similarly to the previous time level and recalling some of the discussions presented by [2] and [4], it was found that the near field is very much influenced by the spanwise direction vortices and these were found to be the ones that act as conveyors to disperse the plume downwind. As these vortices start to decrease in magnitude, a transition was observed.…”

“…The details of the numerical solver are explained in previous papers [4,2]. Validation tests were also presented for the case of free and wall jets [2], and will not be repeated here.…”

“…Figure 4 represents the spanwise vorticity profile behind the complete aircraft after 10 s; the results can be compared with those of [2]. The situation is similar to a jet above the ground in a co-flowing wind condition.…”

“…The LES model adopted is the Dynamic Smagorinsky model described in detail in [2]. Validation was carried out through a staged approach starting from a single engine free in the atmosphere and increasing the complexity step-by-step towards a complete representation of an aircraft on the runway.…”

“…Aloysius and Wrobel [2] presented numerical simulations of the dispersion of buoyant free and wall jets in a coflowing take-off condition. This first step allowed the validation of the CFD codes and a proper assessment of the impact of a solid boundary on the fluid properties.…”