Measurements of the air mass flow and PIV at a ventilation duct test rig

Abstract

The prevailing flow condition of the coolant next to the surface has a significant influence on the effective value of heat transfer by forced convection. Since there is no analytical way for its computation, these flow conditions can only be simulated by computational fluid dynamics (CFD). In order to validate the simulated results of the flow conditions, measurements of the whole velocity field are desirable. These measurements can be accomplished with Particle Image Velocimetry (PIV) which requires a visible access to the coolant’s flow field. Since this visible access cannot be prepared for the ventilation ducts in an operating electrical machine, a ventilation duct test rig with an identical geometry as the ventilation duct inside an electrical machine has been manufactured. This test rig reproduces the flow conditions inside one ventilation duct of a certain electrical machine, allowing optical access to the entire flow field in the rotor and the stator. In the present paper the ventilation duct test rig will be presented with two different setups for measurement. With one measurement setup the total air mass flow rate depending on rotational speed and pressure difference between inlet and outlet has been measured. On the second measurement setup a qualitative and quantitative flow visualization with PIV has been carried out.