E xperimental setup Part of understanding the processes concerning mixing in any apparatus requires a knowledge of the fluid flows in it. There are several ways to obtain this knowledge, one being the visualization of the flow. For the visualisation of the flow a vessel has been built, that can rotate at different speeds. The impeller is mounted on a fixed frame. The vessel contains a fluid containing polystyrene particles.
R esults Pictures have been taken from various planes in the vessel.
The planes cutting through the center of the vessel give the clearest picture of what the flow does. This picture shows that the flow pattern around the helical impeller is rather complex. The flow whirles around the impeller blades, which means that the particle path can be rather complex. In the future these visualization experiments will be combined with the results from laser Doppler velocimetry. An already developed model will be enhanced using these experimental data.