Tumble and swirl (drall) phenomena are measured in a glass cylinder mounted below a real cylinder head and the air is extracted. The object to be measured – a cylinder head or flow box – is mounted on top of the glass cylinder with the same internal diameter as the engine bore.

An Add-on DaVis software package from LaVision is calculating the tumble and swirl numbers by summing up torques, rigid body rotations at all. It can also generate e.g. volume flows and tumble angles. For the Tumble/Swirl number calculation needed parameters like bore diameter and engine stroke are provided by a remote computer system or can be entered manually. The complete LaVision system can be fully controlled by a remote computer which can start recordings, vector field calculations and generating tumble and swirl numbers.