Scale-adaptive simulation (SAS) modelling of a pilot-scale spray dryer

It is now well-established that flows occurring when a jet enters a large vessel are highly transient. Such is the case in spray dryers, where the inlet gas flow can generate transient flow patterns that affect the droplet trajectories and wall deposition behaviour in the dryer significantly. This paper applies the relatively recent scale-adaptive simulation (SAS) approach to the simulation of flow in a pilot-scale dryer. It is shown that this approach produces a much more realistic flowfield than use of URANS equations that have not been adapted to resolve problems associated with their inability to predict turbulence length-scale distributions correctly. A study of the effect of the inlet swirl angle is used to illustrate some features of the transient results. This work makes it clear that transient, 3D simulations of spray dryers can now be made that capture the large-scale turbulence behaviour and that the questionable practice of using unconverged steady-state simulations to provide information is no longer justified.